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WO2021229272A1 - Ensemble comprenant une pile de polymères électroactifs, un élément cible de capteur, un capteur et un dispositif de commande - Google Patents

Ensemble comprenant une pile de polymères électroactifs, un élément cible de capteur, un capteur et un dispositif de commande Download PDF

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Publication number
WO2021229272A1
WO2021229272A1 PCT/IB2020/054557 IB2020054557W WO2021229272A1 WO 2021229272 A1 WO2021229272 A1 WO 2021229272A1 IB 2020054557 W IB2020054557 W IB 2020054557W WO 2021229272 A1 WO2021229272 A1 WO 2021229272A1
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WO
WIPO (PCT)
Prior art keywords
sensor
stack
controller
electroactive polymer
target element
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/IB2020/054557
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English (en)
Inventor
Ronny Krämer
Georg Schürch
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Sateco Xt Ag
Original Assignee
Sateco Xt Ag
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Sateco Xt Ag filed Critical Sateco Xt Ag
Priority to PCT/IB2020/054557 priority Critical patent/WO2021229272A1/fr
Publication of WO2021229272A1 publication Critical patent/WO2021229272A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/0414—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using force sensing means to determine a position
    • G06F3/04142—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means using force sensing means to determine a position the force sensing means being located peripherally, e.g. disposed at the corners or at the side of a touch sensing plate
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/016—Input arrangements with force or tactile feedback as computer generated output to the user
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/50—Piezoelectric or electrostrictive devices having a stacked or multilayer structure
    • H10N30/503—Piezoelectric or electrostrictive devices having a stacked or multilayer structure having a non-rectangular cross-section in a plane orthogonal to the stacking direction, e.g. polygonal or circular in top view
    • H10N30/505—Piezoelectric or electrostrictive devices having a stacked or multilayer structure having a non-rectangular cross-section in a plane orthogonal to the stacking direction, e.g. polygonal or circular in top view the cross-section being annular
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/857—Macromolecular compositions
    • G—PHYSICS
    • G06—COMPUTING OR CALCULATING; COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
    • G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
    • G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
    • G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
    • G06F3/0416—Control or interface arrangements specially adapted for digitisers
    • G06F3/0418—Control or interface arrangements specially adapted for digitisers for error correction or compensation, e.g. based on parallax, calibration or alignment

Definitions

  • An assembly comprising an electroactive polymer stack, a sensor target element, a sensor and a controller
  • the present invention concerns an assembly which has a sensor target element; an electroactive polymer stack; a sensor which is configured to output a variable the value of which changes when the sensor target element is moved relative to the sensor; and a controller which is configured to process said output of the sensor; and wherein said sensor target element is configured to cooperate with said stack so that applying a force to the sensor target element will cause deformation of the stack and movement of the sensor target element relative to the sensor; and wherein applying a voltage to said stack will cause deformation of the stack and movement of the sensor target element relative to the sensor.
  • a compact assembly which can be used to provide tactile feedback to a user.
  • a compact assembly which comprises an sensor target element which the user can apply a force to in order to compress an electroactive polymer stack, and which will provide tactile feedback to the user as soon as the user has compressed said electroactive polymer stack a sufficient amount.
  • a compact assembly which will provide tactile feedback to the user as soon as the user removes the force they applied to compress or expand said electroactive polymer stack.
  • Figure 1a is a perspective view of an assembly according to an embodiment of the present invention.
  • Figure 1 b is a perspective view of the assembly of Figure 1 a showing a user applying a force to the sensor target element so as to compress the electroactive polymer stack of the assembly;
  • Figure 1c is an exploded perspective view of an assembly of Figure 1a;
  • Figure 1d is an exploded perspective view of an assembly according to a further embodiment of the present invention.
  • Figure 1e is an exploded perspective view of an assembly according to a further embodiment of the present invention.
  • Figure 1f is an exploded perspective view of an assembly according to a further embodiment of the present invention
  • Figure 2a is a perspective view of an assembly according to a further embodiment of the present invention
  • Figure 2b is a cross-section view of an assembly of Figure 2a;
  • Figure 2c is a perspective view of the assembly of Figures 2a and 2b, showing a user applying a force to the sensor target element so as to compress the electroactive polymer stack of the assembly;
  • Figure 2d is a cross-section view of the assembly of Figures 2a and 2b, when a user applies a force to the sensor target element so as to compress the electroactive polymer stack of the assembly;
  • Figure 3a is a perspective view of an assembly according to a further embodiment of the present invention.
  • Figure 3b is a cross section view of the assembly of Figure 3a;
  • Figure 3c is a perspective view of the assembly of Figures 3a and 3b, showing a user applying a force to the sensor target element so as to compress the electroactive polymer stack of the assembly;
  • Figure 3d is a cross-section view of the assembly of Figures 3a and 3b, when a user applies a force to the sensor target element so as to compress the electroactive polymer stack of the assembly;
  • Figure 4a is a perspective view of an assembly according to a further embodiment of the present invention.
  • Figure 4b is a cross section view of the assembly of Figure 4a
  • Figure 4c is a cross-section view of the assembly of Figures 4a and 4b, when the electroactive polymer stack is in a compressed state (either due to user applies a force to the sensor target element and/or due to voltage applied to the electrodes in the stack);
  • Figure 5a is a perspective view of an assembly according to a further embodiment of the present invention.
  • Figure 5b is a perspective view of the assembly of Figure 5a, when a user applies a force to the sensor target element so as to compress one or more of the electroactive polymer stacks of the assembly.
  • Figure 1a is a perspective view of an assembly 1 according to an embodiment of the present invention.
  • Figure 1c is an exploded perspective view of an assembly 1 of Figure 1a.
  • the assembly comprises an sensor target element 2; an electroactive polymer stack 3 comprising a plurality of layers of compressible material 3a with a respective electrode 3b interposed between said layers of compressible material 3a; a sensor 4 which is configured to output a variable, wherein the value of said variable changes when the sensor target element 2 is moved relative to the sensor 4; and a controller 5 which is configured to process said variable output of the sensor 4.
  • the controller 5 is electrically connected to the sensor and electrodes 3b of the electroactive polymer stack.
  • the sensor target element 2 is configured to cooperate with said electroactive polymer stack 3, so that applying a force to the sensor target element 2 will cause deformation of the electroactive polymer stack 3 and movement of the sensor target element 2 relative to the sensor 4.
  • said electroactive polymer stack 3 is mounted on the sensor 4
  • the sensor target element 2 is mounted on the electroactive polymer stack 3, so that the electroactive polymer stack 3 is sandwiched between the sensor target element 2 and the sensor 4.
  • the sensor 4 and the sensor target element 2 may take any suitable form.
  • the sensor target element 2 may be a metallic element, a magnetic element, or an optical element.
  • the sensor target element 2 comprises a metallic element 2; for example the sensor target element 2 may comprise a metallic disc 2.
  • the sensor 4 may be an inductive sensor, a capacitive sensor, a magnetic sensor or an optical sensor.
  • the sensor 4 is an inductive sensor 4 which comprises an induction coil 4a which can conduct a current.
  • the induction coil 4a is provided on a PCB board 4b.
  • the variable which is output by said sensor 4 is an electric variable; specifically, the current conducted in said induction coil 4a defines said variable which is output by said sensor 4.
  • FIG 1b is a perspective view of the assembly 1 of Figure 1a showing a user applying a force to the metallic element 2 (sensor target element 2) so as to compress the electroactive polymer stack of the assembly 1.
  • the metallic element 2 when the user applies a force to the metallic element 2 so as to compress the electroactive polymer stack of the assembly 1 the metallic element 2 is moved closer to the induction coil 4a of the inductive sensor 4.
  • the metallic element 2 moves closer to the induction coil 4 the metallic element 2 moves into the magnetic field generated by the current conducted in said induction coil 4a to cause the generation of eddy currents in the induction coil 4a; the eddy currents increase the amount of current conducted in the induction coil 4a.
  • moving the metallic element 2 towards the induction coil 4a of the inductive sensor 4 increases the current flowing in the induction coil 4a.
  • the nature of the changes in the current in the induction coil 4a depends on the composition of the sensor target element 2; for example if the sensor target element 2 comprises ferrometals, then the changes in the current in the induction coil 4a as the sensor target element 2 moves towards or away from the inductive sensor 4 will be different compares to the changes in the current in the induction coil 4a as the sensor target element 2 moves towards or away from the inductive sensor 4 if the sensor target element 2 comprised non-ferrometal.
  • controller 5 is configured to process said variable output of the sensor 4; in other words, in this embodiment, the controller 5 is configured to process the current flowing in the induction coil 4a.
  • the controller 5 is preferably configured to process said variable output from the sensor 4 to determine if the output satisfies a predefined condition, and to apply a voltage to the electrodes 3b in said electroactive polymer stack 3 to cause the electroactive polymer stack 3 to compress if the variable output of the sensor does satisfy said predefined condition.
  • the controller 5 could be configured to process said variable output of the sensor 4 by comparing said variable output to a predefined threshold, and if the variable output is above said predefined threshold then the controller 5 is configured to apply a voltage to the electrodes 3b in said electroactive polymer stack 3 to cause the stack to compress.
  • the controller 5 is preferably configured to process the current flowing in the induction coil 4a, by comparing the level of current flowing in the induction coil 4a to a first predefined threshold current level; then the controller 5 is configured to apply a voltage to the electrodes 3b in said electroactive polymer stack 3 to cause the stack to compress if the level of current flowing in the induction coil 4a is greater than the first predefined threshold current level.
  • the controller 5 applies a voltage to the electrodes 3b in this causes the electrodes 3b to move towards one another; as the electrodes 3b move towards one another they compress the layers of flexible material 3a, thus resulting in the compression of the electroactive polymer stack 3.
  • the controller 5 applies a pulse of voltage to the electrodes 3b in the electroactive polymer stack 3, to cause the electroactive polymer stack 3 to compress.
  • the controller 5 is further preferably configured to process said variable output from the sensor 4 to determine if the output satisfies a predefined condition, and to discharge the electrodes 3b in said electroactive polymer stack 3; when the electrodes 3b in said electroactive polymer stack are discharge the electroactive polymer stack 3 to elastically return to its original shape.
  • the controller 5 could be configured to process said variable output of the sensor 4 by comparing said variable output to a predefined threshold, and if the variable output is below said predefined threshold then the controller 5 is configured to discharge the electrodes 3b in said electroactive polymer stack 3.
  • the controller 5 is configured to compare the level of current flowing in the induction coil 4a to the second predefined threshold current level, after the controller 5 has applied a voltage to the electrodes 3b which caused the electroactive polymer stack 3 to compress; in other words the electroactive polymer stack 3 is already in a compressed state when the controller 5 compares the level of current flowing in the induction coil 4a to the second predefined threshold current level; therefore subsequent discharging of the electrodes 3b will allow the electroactive polymer stack 3 to elastically return to its original shape.
  • the controller 5 is preferably configured to process the current flowing in the induction coil 4a, by comparing the level of current flowing in the induction coil 4a to a second predefined threshold current level; the controller 5 is configured to discharge the electrodes 3b in said electroactive polymer stack 3 to allow the stack to eclectically return to its original shape, if the level of current flowing in the induction coil 4a is less than the second predefined threshold current level.
  • the sensor target element 2 When the user applies a force to the sensor target element 2 so as to compress the electroactive polymer stack of the assembly 1 the sensor target element 2 is moved closer to the induction coil 4a of the inductive sensor 4. As the sensor target element 2 moves closer to the induction coil 4a this increases the amount of current conducted in the induction coil 4a so that it exceeds the first predefined threshold current level.
  • the controller 5 applies a voltage to the electrodes 3b in the electroactive polymer stack 3, to cause the electroactive polymer stack 3 to compress; the compression and/or expansion of the electroactive polymer stack 3 provides the user with tactile feedback.
  • the controller 5 applies a pulse of voltage to the electrodes 3b in the electroactive polymer stack 3, to cause the electroactive polymer stack 3 to compress.
  • the sensor target element 2 begins to move away from the induction coil 4a, resulting in a decrease of the current flowing in the induction coil 4a so that the level of current drops below the second predefined threshold current level.
  • the controller 5 discharges the electrodes 3b in the electroactive polymer stack 3, to allow the electroactive polymer stack 3 to expand from its compressed state to elastically return to its original shape; the expansion of the electroactive polymer stack 3 back to its original shape provides the user with tactile feedback.
  • the original shape of the electroactive polymer stack 3 is the shape which the electroactive polymer stack 3 had prior to the user applying a force to the sensor target element 2.
  • the controller is configured to process said variable output of the sensor 5 to determine the amount which said electroactive polymer stack has been compressed.
  • the controller 5 may be configured to determine, based on the level of current flowing in the induction coil 4a, how much the user has compressed the electroactive polymer stack 3.
  • the controller 5 may use a look-up table which was constructed during a calibration step and which contains a plurality of different current levels, and a respective compression measurement for each respective current level in the table.
  • the controller may be configured to receive from the sensor 4 the level of current flowing in the induction coil 4a and to then identify the corresponding compression measurement in the look-up table to determine the amount which the user has compressed the electroactive polymer stack 3.
  • the controller is further configured to process said afore-mentioned determined amount which the user has compressed the electroactive polymer stack 3 to determine the force which has been applied to the sensor target element 2.
  • the controller is configured to process said variable output of the sensor 5 to determine the force which has been applied to the sensor target element 2.
  • the controller 5 may be configured to determine, based on the level of current flowing in the induction coil 4a, how much force the user has applied to the sensor target element 2.
  • the controller 5 may use a look-up table which was constructed during a calibration step and which contains a plurality of different current levels, and a respective force measurement for each respective current level in the table.
  • the controller may be configured to receive from the sensor 4 the level of current flowing in the induction coil 4a and to then identify the corresponding force measurement in the look-up table to determine the amount of force which the user has applied to the actuating member 2.
  • the controller is configured to control the voltage which is applied to the electrodes 3b in the stack 3, and/or the discharge of the electrodes so that the sensor target element 2 is moved to a predefined set-point position.
  • the controller 5 is configured to process said variable output of the sensor 4 (which in the assembly 1 is the current flowing in the induction coil 4a) to determine the position of the sensor target element 2; and then to compare the determined position to a predefined set-point position.
  • the controller 5 is further configured to increase the voltage applied to the electrodes 3b in the stack 3 if the determined position of the sensor target element 2 is above the predefined set-point position; and to partially or fully discharge the electrodes 3b if the determined position of the sensor target element 2 is below the predefined set-point position.
  • discharging (partially or fully) the electrodes 3b in the stack 3 will cause the stack 3 to expand (from a previously contracted state); as the stack 3 expands the sensor target element 2 which is mounted on the stack will be moved to a higher position; thus if the determined position of the sensor target element 2 is below the predefined set-point position then discharging (partially or fully) will move the sensor target element 2 closer to the predefined set-point position.
  • the controller 5 may be configured to process said variable output of the sensor 4 (which in the assembly 1 is the current flowing in the induction coil 4a) to determine the position of the sensor target element 2 using any suitable means.
  • a calibration step is carried out wherein the level of current flowing in the induction coil 4a and the corresponding position of the sensor target element 2 is recorded when no voltage is applied to the electrodes 3b in the stack 3; and the current flowing in the induction coil 4a together with the position is recorded in a memory of the controller 5; next a maximum level of voltage is applied to the electrodes 3b in the stack 3 , and the level of the current flowing in the induction coil 4a together with the position is recorded in a memory of the controller 5.
  • a minimum position value which is the position occupied by the sensor target element 2 when no voltage is applied to the stack 3, together with a minimum induction current level which is the level of current flowing in the induction coil 4a when no voltage is applied to the stack 3; a maximum position value which is the position occupied by the sensor target element 2 when a maximum voltage is applied to the stack 3, together with a maximum induction current level which is the level of current flowing in the induction coil 4a when a maximum voltage is applied to the stack 3.
  • the controller is configured to use the calibrated, minimum position value, minimum induction current, level maximum position value, and maximum induction current level to determine, by interpolation, the position of the sensor target element 2 from any level of current flowing in the induction coil 4a as output from the sensor 4.
  • the controller determines the position of the sensor target element to be correspondingly mid-way between the maximum and minimum position value; in other words the controller can determine the position of the sensor target element 2 to be '5mm'.
  • This embodiment is especially useful when there is a substantially linear relationship between the position of the sensor target element 2 and the level of current flowing in the induction coil 4a.
  • the calibration step comprises applying a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the level of current flowing in the induction coil 4a and the corresponding position of the sensor target element 2.
  • the controller 5 is configured to use said plurality of recorded levels of current flowing in the induction coil 4a and positions of the sensor target element 2 to determine, by interpolation (if necessary), the position of the sensor target element 2 from any level of current flowing in the induction coil 4a as output from the sensor 4.
  • a look-up take is formed during the calibration step: a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the level of current flowing in the induction coil 4a and the corresponding position of the sensor target element 2 in a look-up table.
  • the resulting look-up table will comprise a plurality of different levels of current flowing in the induction coil 4a and a respective position of the sensor target element 2 associated with each respective level of current.
  • the controller 5 is configured to use the look-up table to determine the position of the sensor target element 2 from any level of current flowing in the induction coil 4a as output from the sensor 4.
  • the controller 5 receives a level of current flowing in the induction coil 4a output from the sensor 4; the controller 5 then identifies the corresponding current level in the look-up table; the controller 5 then identifies the position associated with said identified current level in the look-up table, as being the position which the sensor target element 2 currently occupies.
  • FIG. 1d is an exploded perspective view of an assembly 10 according to a further embodiment of the present invention.
  • the assembly 10 has many of the same features as the assembly 1 shown in Figures 1a-1c and like features are awarded the same reference numbers.
  • the sensor 4 is a capacitive sensor 40 which comprises a capacitive electrode 40a.
  • the sensor target element 2 comprises a metallic element 2; for example, the sensor target element 2 may comprise a metallic disc 2.
  • the metallic element 2 and capacitive electrode 40a define a capacitor (the metallic element 2 defining one capacitive plate and the capacitive electrode 40a defining the opposite capacitive plate of the capacitor); capacitance of the said capacitor defines said variable which is output by said sensor 4.
  • the capacitance of the capacitor can be measured by the sensor 4 in any suitable way.
  • the measure of the capacitance of the capacitor may involve using for, example, a capacitance to frequency converter, or a capacitance to time converter, or a capacitance to voltage converter.
  • the assembly 10 works in a similar fashion to the assembly 1 except it uses the capacitance of the capacitor as output from the sensor 4.
  • the variable output of the sensor 4 is a measure of the capacitance of the capacitor.
  • the controller 5 is preferably configured to process said capacitance of the capacitor as output from the sensor 4 by comparing the capacitance of the capacitor as output from the sensor 4 to a first predefined threshold capacitance level.
  • the controller 5 is configured to apply a voltage to the electrodes 3b in said electroactive polymer stack 3 to cause the stack to compress if the capacitance of the capacitor as output from the sensor 4 is greater than the first predefined threshold capacitance level.
  • the controller 5 is configured to compare the capacitance of the capacitor as output from the sensor 4 to the second predefined threshold capacitance level, after the controller 5 has applied a voltage to the electrodes 3b which caused the electroactive polymer stack 3 to compress; in other words the electroactive polymer stack 3 is already in a compressed state when the controller 5 compares the capacitance of the capacitor as output from the sensor 4 to the second predefined threshold capacitance level.
  • the controller 5 is configured to discharge the electrodes 3b in said electroactive polymer stack 3 to allow the stack to eclectically return to its original shape, if the capacitance of the capacitor as output from the sensor 4 is less than the second predefined capacitance level.
  • controller 5 in the assembly 10 could be configured to determine how much the stack has been compressed and/or the force which the user has applied to the sensor target element 2 from said capacitance of the capacitor as output from the sensor 4, in a similar fashion to the manner in which the assembly 1 may do so using the level of current in the induction coil 4a as output by the sensor.
  • the controller is configured to control the voltage which is applied to the electrodes 3b in the stack 3, and/or the discharge of the electrodes so that the sensor target element 2 is moved to a predefined set-point position.
  • the controller 5 is configured to process said variable output of the sensor 4 (which in the assembly 10 is the capacitance of the capacitor (i.e. the capacitor being defined by the metallic element 2 and capacitive electrode 40a define a capacitor (the metallic element 2 defining one capacitive plate and the capacitive electrode 40a defining the opposite capacitive plate of the capacitor)) to determine the position of the sensor target element 2; and then to compare the determined position to a predefined set-point position.
  • the controller 5 is further configured to increase the voltage applied to the electrodes 3b in the stack 3 if the determined position of the sensor target element 2 is above the predefined set-point position; and to partially or fully discharge the electrodes 3b if the determined position of the sensor target element 2 is below the predefined set-point position.
  • Increasing the voltage applied to the electrodes 3b in the stack 3 will cause the stack 3 to contract; as the stack 3 contracts the sensor target element 2 which is mounted on the stack will be moved to a lower position; thus if the determined position of the sensor target element 2 is above the predefined set-point position increasing the voltage applied to the electrodes 3b in the stack will move the sensor target element 2 closer to the predefined set-point position.
  • discharging (partially or fully) the electrodes 3b in the stack 3 will cause the stack 3 to expand (from a previously contracted state); as the stack 3 expands the sensor target element 2 which is mounted on the stack will be moved to a higher position; thus if the determined position of the sensor target element 2 is below the predefined set-point position then discharging (partially or fully) will move the sensor target element 2 closer to the predefined set-point position.
  • the controller 5 may be configured to process said variable output of the sensor 4 (which in the assembly 10 is the capacitance of the capacitor) to determine the position of the sensor target element 2 using any suitable means.
  • a calibration step is carried out wherein the level of capacitance of the capacitor and the corresponding position of the sensor target element 2 is recorded when no voltage is applied to the electrodes 3b in the stack 3; and the level of capacitance of the capacitor together with the position of the sensor target element 2 is recorded in a memory of the controller 5; next a maximum level of voltage is applied to the electrodes 3b in the stack 3 , and the level of capacitance of the capacitor together with the position of the sensor target element 2 is recorded in a memory of the controller 5.
  • a minimum position value which is the position occupied by the sensor target element 2 when no voltage is applied to the stack 3, together with a minimum capacitance which is the level of capacitance of the capacitor when no voltage is applied to the stack 3; a maximum position value which is the position occupied by the sensor target element 2 when a maximum voltage is applied to the stack 3, together with a maximum capacitance which is the level of capacitance of the capacitor when a maximum voltage is applied to the stack 3.
  • the controller is configured to use the calibrated, minimum position value, minimum capacitance, maximum position value, and maximum capacitance, to determine, by interpolation between these values, the position of the sensor target element 2 from any level of level of capacitance of the capacitor as output from the sensor 4. This embodiment is especially useful when there is a substantially linear relationship between the position of the sensor target element 2 and the level of capacitance of the capacitor.
  • the calibration step comprises applying a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the level of capacitance of the capacitor and the corresponding position of the sensor target element 2.
  • the controller 5 is configured to use said plurality of recorded levels of capacitance of the capacitor and positions of the sensor target element 2 to determine, by interpolation (if necessary), the position of the sensor target element 2 from any level of capacitance of the capacitor as output from the sensor 4.
  • a look-up take is formed during the calibration step: a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the level of capacitance of the capacitor and the corresponding position of the sensor target element 2 in a look-up table.
  • the resulting look-up table will comprise a plurality of different levels of capacitance of the capacitor and a respective position of the sensor target element 2 associated with each respective level of capacitance.
  • the controller 5 is configured to use the look-up table to determine the position of the sensor target element 2 from any level of capacitance of the capacitor as output from the sensor 4.
  • the controller 5 receives the level of capacitance of the capacitor output from the sensor 4; the controller 5 then identifies the corresponding level of capacitance in the look-up table; the controller 5 then identifies the position associated with said identified current level in the look-up table, as being the position which the sensor target element 2 currently occupies.
  • Figure 1e is an exploded perspective view of an assembly 20 according to a further embodiment of the present invention.
  • the assembly 20 has many of the same features as the assembly 1 shown in Figures 1a-1c and like features are awarded the same reference numbers.
  • the sensor 4 is a magnetic sensor 50 which can measure magnetic field.
  • the sensor target element 2 comprises a magnetic element 2a; for example, the sensor target element 2 may comprise a magnetic disc 2a.
  • the level of magnetic field measured by the magnetic sensor 50 defines said variable which is output by said sensor 4. Movement of the magnetic element 2a closer to the magnetic sensor 50 results in an increase in the magnetic field which is sensed by the magnetic sensor 50 and movement of the magnetic element 2a away from the magnetic sensor 50 results in a decrease in the magnetic field which is sensed by the magnetic sensor 50.
  • the assembly 20 works in a similar fashion to the assembly 1 except it uses a measure of the magnetic field in the region of the sensor 4 (magnetic sensor 50).
  • the variable output of the sensor 4 is a measure of the magnetic field in the region of the magnetic sensor 50.
  • the controller 5 is preferably configured to process said measure of the magnetic field as output from the sensor 4 by comparing the measure of the magnetic field as output from the sensor 4 to a first predefined threshold magnetic field level.
  • the controller 5 is configured to apply a voltage to the electrodes 3b in said electroactive polymer stack 3 to cause the stack to compress if the measure of the magnetic field as output from the sensor 4 is greater than the first predefined threshold magnetic field level.
  • the controller 5 is configured to compare the measure of the magnetic field as output from the sensor 4 to a second predefined threshold magnetic field level, after the controller 5 has applied a voltage to the electrodes 3b which caused the electroactive polymer stack 3 to compress; in other words the electroactive polymer stack 3 is already in a compressed state when the controller 5 compares the measure of the magnetic field as output from the sensor 4 to the second predefined threshold magnetic field level.
  • the controller 5 is configured to discharge the electrodes 3b in said electroactive polymer stack 3 to allow the stack to eclectically return to its original shape, if the measure of the magnetic field as output from the sensor 4 is less than the second predefined magnetic field level.
  • controller 5 in the assembly 20 could be configured to determine how much the stack has been compressed and/or the force which the user has applied to the sensor target element 2 from said measure of the magnetic field as output from the sensor 4, in a similar fashion to the manner in which the assembly 1 may do so using the level of current in the induction coil 4a as output by the sensor.
  • the controller is configured to control the voltage which is applied to the electrodes 3b in the stack 3, and/or the discharge of the electrodes so that the sensor target element 2 is moved to a predefined set-point position.
  • the controller 5 is configured to process said variable output of the sensor 4 (which in the assembly 20 is the measure of the magnetic field as output from the sensor 4) to determine the position of the sensor target element 2; and then to compare the determined position to a predefined set-point position.
  • the controller 5 is further configured to increase the voltage applied to the electrodes 3b in the stack 3 if the determined position of the sensor target element 2 is above the predefined set-point position; and to partially or fully discharge the electrodes 3b if the determined position of the sensor target element 2 is below the predefined set-point position.
  • discharging (partially or fully) the electrodes 3b in the stack 3 will cause the stack 3 to expand (from a previously contracted state); as the stack 3 expands the sensor target element 2 which is mounted on the stack will be moved to a higher position; thus if the determined position of the sensor target element 2 is below the predefined set-point position then discharging (partially or fully) will move the sensor target element 2 closer to the predefined set-point position.
  • the controller 5 may be configured to process said variable output of the sensor 4 (which in the assembly 20 is the measure of the magnetic field as output from the sensor 4) to determine the position of the sensor target element 2 using any suitable means.
  • a calibration step is carried out wherein the level of magnetic field measured by the magnetic sensor 50 and the corresponding position of the sensor target element 2 is recorded when no voltage is applied to the electrodes 3b in the stack 3; and the level of magnetic field measured by the magnetic sensor 50 together with the position of the sensor target element 2 is recorded in a memory of the controller 5; next a maximum level of voltage is applied to the electrodes 3b in the stack 3 , and the level of magnetic field measured by the magnetic sensor 50 together with the position of the sensor target element 2 is recorded in a memory of the controller 5.
  • a minimum position value which is the position occupied by the sensor target element 2 when no voltage is applied to the stack 3, together with a minimum magnetic field which is the level of magnetic field measured by the magnetic sensor 50 when no voltage is applied to the stack 3
  • a maximum position value which is the position occupied by the sensor target element 2 when a maximum voltage is applied to the stack 3, together with a maximum magnetic field which is the level of magnetic field measured by the magnetic sensor 50 when a maximum voltage is applied to the stack 3.
  • the controller is configured to use the calibrated, minimum position value, minimum magnetic field, maximum position value, and maximum magnetic field, to determine, by interpolation between these values, the position of the sensor target element 2 from any level of magnetic field (measured by the magnetic sensor 50) as output from the sensor 4.
  • This embodiment is especially useful when there is a substantially linear relationship between the position of the sensor target element 2 and the level of magnetic field measured by the magnetic sensor 50.
  • the calibration step comprises applying a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the level of magnetic field measured by the magnetic sensor 50 and the corresponding position of the sensor target element 2.
  • the controller 5 is configured to use said plurality of recorded levels of magnetic field and positions of the sensor target element 2 to determine, by interpolation (if necessary), the position of the sensor target element 2 from any level of magnetic field as output from the sensor 4.
  • a look-up take is formed during the calibration step: a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the level of magnetic field measured by the magnetic sensor 50 and the corresponding position of the sensor target element 2 in a look-up table.
  • the resulting look-up table will comprise a plurality of different levels of magnetic field and a respective position of the sensor target element 2 associated with each respective level of magnetic field.
  • the controller 5 is configured to use the look-up table to determine the position of the sensor target element 2 from any level of magnetic field as output from the sensor 4.
  • the controller 5 receives the level of magnetic field output from the sensor 4; the controller 5 then identifies the corresponding level of magnetic field in the look-up table; the controller 5 then identifies the position associated with said identified level of magnetic field in the look-up table, as being the position which the sensor target element 2 currently occupies.
  • Figure 1f is an exploded perspective view of an assembly 30 according to a further embodiment of the present invention.
  • the assembly has many of the same features as the assembly 1 in Figure 1 a, and like features are awarded the same reference numbers.
  • the assembly 30 further comprises a reference sensor 4r and a reference sensor target 2r.
  • the reference sensor 4r and reference sensor target 2r may take any suitable form; however most preferably the reference sensor 4r will be the same type of sensor as the sensor 4 and the reference sensor target 2r will be composed of the same material as the material from which the sensor target element 2 is composed.
  • the controller is configured to determine the difference between the variable output by the senor 4 and the variable output by the reference sensor 4r; and then to determine if said difference satisfies a predefined condition.
  • the controller is further configured to apply a voltage to the electrodes in said electroactive polymer stack to cause the electroactive polymer stack to compress if the difference satisfies the predefined condition, and/or, to discharge the electrodes in said electroactive polymer stack to cause the electroactive polymer stack to contract if the difference satisfies the predefined condition
  • the reference sensor target 2r may be a metallic element, a magnetic element, or an optical element.
  • the reference sensor target 2r comprises a metallic element 2a (the same as the composition of the sensor target element 2).
  • the reference sensor 4r may be an inductive sensor, a capacitive sensor, a magnetic sensor or an optical sensor.
  • the reference sensor 4r is an inductive sensor, the same at the sensor 4 which is also an inductive sensor.
  • the reference sensor 4r comprises a reference induction coil 4ar.
  • the location of the reference sensor target 2r is fixed with respect to the reference sensor 4r.
  • the position of the reference sensor target 2r is fixed with respect to the reference induction coil 4ar. Since the position of the reference sensor target 2r is fixed with respect to the reference induction coil 4ar any changes which might occur in the induction current flowing in the reference induction coil 4ar are attributed to factors other than the movement of the reference sensor target 2r.
  • the controller 5 is configured to process said variable output of the sensor 4 and also the variable output by the reference sensor 4r; in other words, in this embodiment, the controller 5 is configured to process the current flowing in the induction coil 4a and also the current flowing in the reference induction coil 4ar.
  • the controller 5 is configured to determine the difference between the current flowing in the induction coil 4a and the current flowing in the reference induction coil 4ar; and then to determine if said difference satisfies a predefined condition.
  • the controller 5 is further configured to determine if the difference satisfies a predefined condition.
  • the controller 5 is further configured to apply a voltage to the electrodes 3b in said electroactive polymer stack 3 to cause the electroactive polymer stack 3 to compress if the difference satisfies the predefined condition, and/or, to discharge the electrodes 3b in said electroactive polymer stack 3 to cause the electroactive polymer stack 3 to contract if the difference satisfies the predefined condition.
  • the controller 5 is preferably configured to: process the current flowing in the induction coil 4a and also the current flowing in the reference induction coil 4ar, by determining the difference between the current flowing in the induction coil 4a and the current flowing in the reference induction coil 4ar; compare the difference to a first predefined threshold current level; and to apply a voltage to the electrodes 3b in said electroactive polymer stack 3 to cause the stack to compress if the difference is greater than, or equal to, the first predefined threshold current level.
  • the controller 5 is further configured to the controller 5 is preferably configured to: process the current flowing in the induction coil 4a and also the current flowing in the reference induction coil 4ar, by determining the difference between the current flowing in the induction coil 4a and the current flowing in the reference induction coil 4ar; compare the difference to a second predefined threshold current level; and to discharge the electrodes 3b in said electroactive polymer stack 3 if the difference is equal to, or less than, said second predefined threshold current level.
  • the controller is configured to carry out these steps (i.e.
  • the controller 5 determines the difference and compare the difference to the second predefined threshold current level; and then discharge the electrodes 3b in said electroactive polymer stack 3 if the difference is below said second predefined threshold current level ) after the controller 5 has applied a voltage to the electrodes 3b which caused the electroactive polymer stack 3 to compress; in other words the electroactive polymer stack 3 is already in a compressed state when the controller 5 compares the difference to the second predefined threshold current level, therefore subsequent discharging of the electrodes 3b will allow the electroactive polymer stack 3 to elastically return to its original shape.
  • the advantage of providing a reference sensor 4r and reference sensor target 2r is that it enables to compensate for noise in the variable output of the sensor 4 (i.e. noise in the current flowing in the induction coil 4a); in particular, it enables to compensate for external factors other than movement of the sensor target element 2, which can change the level current flowing in the induction coil 4a of the sensor 4. Examples of possible external factors may include, for example, certain temperature conditions, and/or humidity, and/or any other environment influence, which may cause a change in the current flowing in the sensor 4.
  • the sensor target element 2 When the sensor target element 2 is moved so as to compress the electroactive polymer stack 3, the sensor target element 2 is moved closer to the induction coil 4a of the inductive sensor 4 (e.g. when a user applies a force to move the sensor target element 2 towards the inductive sensor 4). As the sensor target element 2 moves closer to the induction coil 4a this increases the amount of current conducted in the induction coil 4a; at the same time the current flowing in the reference induction coil 4ar will remain unchanged as the reference sensor target 2r remains in a fixed position relative to the reference induction coil 4ar. Accordingly, the difference between the current flowing in the induction coil 4a and the current flowing in the reference induction coil 4ar will increase.
  • the controller will apply a voltage to the electrodes 3b in said electroactive polymer stack 3 to cause the stack to compress.
  • the sensor target element 2 subsequently moves away from the induction coil 4a of the inductive sensor 4 (e.g when the user begins to remove the force they apply to the sensor target element 2, the sensor target element 2 begins to move away from the induction coil 4a), this results in a decrease of the current flowing in the induction coil 4a.
  • the current flowing in the reference induction coil 4ar will remain unchanged as the reference sensor target 2r remains in a fixed position relative to the reference induction coil 4ar.
  • the difference between the current flowing in the induction coil 4a and the current flowing in the reference induction coil 4ar will decrease.
  • the controller will discharge the electrodes 3b in said electroactive polymer stack 3 thereby allowing the electroactive polymer stack 3 to expand from its compressed states back to its original shape (i.e. the stack will elastically return to its original shape).
  • the compression of the stack 3, and expansion of the stack can be used to provide tactile feedback to a user.
  • the controller 5 is configured to control the voltage which is applied to the electrodes 3b in the stack 3, and/or the discharge of the electrodes so that the sensor target element 2 is moved to a predefined set-point position.
  • the controller 5 is configured to process said variable output of the sensor 4, which in the assembly 30 if the current flowing in the induction coil 4a and also the current flowing in the reference induction coil 4ar, to determine the difference between the current flowing in the induction coil 4a and the current flowing in the reference induction coil 4ar.
  • the differential current the difference between the current flowing in the induction coil 4a and the current flowing in the reference induction coil 4ar will be referred to as the differential current.
  • the controller is further configured to determine the position of the sensor target element 2 from said differential current; and then to compare the determined position to a predefined set-point position.
  • the controller 5 is further configured to increase the voltage applied to the electrodes 3b in the stack 3 if the determined position of the sensor target element 2 is above the predefined set-point position; and to partially or fully discharge the electrodes 3b if the determined position of the sensor target element 2 is below the predefined set-point position.
  • Increasing the voltage applied to the electrodes 3b in the stack 3 will cause the stack 3 to contract; as the stack 3 contracts the sensor target element 2 which is mounted on the stack will be moved to a lower position; thus if the determined position of the sensor target element 2 is above the predefined set-point position increasing the voltage applied to the electrodes 3b in the stack will move the sensor target element 2 closer to the predefined set- point position.
  • discharging (partially or fully) the electrodes 3b in the stack 3 will cause the stack 3 to expand (from a previously contracted state); as the stack 3 expands the sensor target element 2 which is mounted on the stack will be moved to a higher position; thus if the determined position of the sensor target element 2 is below the predefined set-point position then discharging (partially or fully) will move the sensor target element 2 closer to the predefined set-point position.
  • the controller 5 may be configured to process said differential current to determine the position of the sensor target element 2 using any suitable means.
  • a calibration step is carried out wherein the level of differential current and the corresponding position of the sensor target element 2 is recorded when no voltage is applied to the electrodes 3b in the stack 3; and the level of differential current, together with the position is recorded in a memory of the controller 5; next a maximum level of voltage is applied to the electrodes 3b in the stack 3 , and the level of differential current together with the position is recorded in a memory of the controller 5.
  • a minimum position value which is the position occupied by the sensor target element 2 when no voltage is applied to the stack 3, together with a minimum differential current level which is the level of differential current when no voltage is applied to the stack 3; a maximum position value which is the position occupied by the sensor target element 2 when a maximum voltage is applied to the stack 3, together with a maximum differential current level which is the level of differential current when a maximum voltage is applied to the stack 3.
  • the controller is configured to use the calibrated, minimum position value, minimum differential current level, maximum position value, and maximum differential current level to determine, by interpolation, the position of the sensor target element 2 from any level of differential current determined by the controller 5 from the difference between the current flowing in the induction coil 4a and the current flowing in the reference induction coil 4ar output by the sensor 4.
  • the minimum position value is '10mm'
  • the minimum differential current level is ⁇ Amp'
  • the maximum position value is '1mm'
  • maximum differential current level is '10 Amp'
  • the controller determines the position of the sensor target element to be correspondingly mid-way between the maximum and minim position value; in other words the controller can determine the position of the sensor target element 2 to be '5mm'.
  • This embodiment is especially useful when there is a substantially linear relationship between the position of the sensor target element 2 and the level of differential current.
  • the calibration step comprises applying a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the differential current level and the corresponding position of the sensor target element 2.
  • the controller 5 is configured to use said plurality of recorded levels of differential current level and positions of the sensor target element 2 to determine, by interpolation (if necessary), the position of the sensor target element 2 from any level of differential current determined by the controller 5 from the difference between the current flowing in the induction coil 4a and the current flowing in the reference induction coil 4ar output by the sensor 4.
  • a look-up take is formed during the calibration step: a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the level of differential current and the corresponding position of the sensor target element 2 in a look-up table.
  • the resulting look-up table will comprise a plurality of different current levels and a respective position of the sensor target element 2 associated with each respective level of differential current.
  • the controller 5 is configured to use the look-up table to determine the position of the sensor target element 2 from any level of differential current determined by the controller 5.
  • the controller 5 receives the current flowing in the induction coil 4a and the current flowing in the reference induction coil 4ar output by the sensor 4; the controller then determines the differential current; the controller 5 then identifies the corresponding differential current level in the look-up table; the controller 5 then identifies the position associated with said identified current level in the look-up table, as being the position which the sensor target element 2 currently occupies.
  • Figure 2a is a perspective view of an assembly 200 according to a further embodiment of the present invention.
  • Figure 2b is a cross-section view of an assembly 200.
  • Figure 2c is a perspective view of the assembly 200 showing a user applying a force to the sensor target element so as to compress the electroactive polymer stack of the assembly.
  • Figure 2d is a cross-section view of the assembly 200, when a user applies a force to the sensor target element so as to compress the electroactive polymer stack of the assembly.
  • the assembly 200 has many of the same features as the assembly 1 shown in Figures 1a-1c and like features are awarded the same reference numbers. Specifically the assembly 200 comprises a sensor target element 2; an electroactive polymer stack 3 comprising a plurality of layers of compressible material 3a with a respective electrode 3b interposed between said layers of compressible material 3a; a sensor 4 which is configured to output a variable, wherein the value of said variable changes when the sensor target element 2 is moved relative to the sensor 4; and a controller 5 which is configured to process said variable output of the sensor 4.
  • the controller 5 is electrically connected to the electrodes 3b in the electroactive polymer stack 3.
  • the sensor 4 may take any suitable form and sensor target element 2 may take any suitable form.
  • the sensor 4 may be an inductive sensor, a capacitive sensor, a magnetic sensor or an optical sensor; the sensor target element 2 may comprise a metallic element, a magnetic element, or an optical element.
  • the sensor is an inductive sensor 4 having the same features as the inductive sensor 4 of the assembly 1 shown in Figures 1a-1c.
  • the sensor target element 2 comprises a plate element 20a and a metallic element 20b and a shaft 20c, and wherein the shaft 20c is connected between the plate element 20a and the metallic element 20b.
  • the electroactive polymer stack 3 and sensor 4 each have a respective through-hole 3d,4d defined therein.
  • the shaft 20c of the sensor target element 2 is located in the through holes 3d,4d so that the electroactive polymer stack 3 and sensor 4 is located between the plate element 20a and the metallic element 20b.
  • the metallic element 20b moves away from the induction coil 4
  • the metallic element 20b moves away from the magnetic field generated by the current conducted in said induction coil 4a
  • the reduction in eddy currents in turn leads to a decrease in the level of current conducted in the induction coil 4a.
  • the further the metallic element 20b is moved away from the induction coil 4a of the inductive sensor 4 the larger the decrease in the level of current flowing in the induction coil 4a; correspondingly, movement of the metallic element 2 towards the induction coil 4a increases the current flowing in the induction coil 4a.
  • the controller 5 is configured to process said variable output of the sensor 4; in other words, in this embodiment, the sensor 4 outputs the level of current flowing in its respective induction coil 4a to the controller 5, and the controller 5 is configured to process that level of current flowing in its respective induction coil 4.
  • the controller 5 is preferably configured to process the current flowing in the induction coil 4a, by comparing the level of current flowing in the induction coil 4a to a first predefined threshold current level; then the controller 5 is configured to apply a voltage to the electrodes 3b in said electroactive polymer stack 3 to cause the stack to compress if the level of current flowing in the induction coil 4a is less than a first predefined threshold current level.
  • the controller applies a voltage to the electrodes 3b in this causes the electrodes 3b to move towards one another; as the electrodes 3b move towards one another they compress the layers of flexible material 3a, thus resulting in the compression of the electroactive polymer stack 3.
  • the controller 5 applies a pulse of voltage to the electrodes 3b in the electroactive polymer stack 3, to cause the electroactive polymer stack 3 to compress.
  • the controller 5 is also configured to compare the level of current flowing in the induction coil 4a to a second predefined threshold current level, after the controller 5 has applied a voltage to the electrodes 3b which caused the electroactive polymer stack 3 to compress; and the controller 5 is preferably configured to discharge the electrodes 3b in said electroactive polymer stack 3 if the level of current is above said second predefined threshold current level.
  • the controller 5 is preferably configured to process the current flowing in the induction coil 4a, by comparing the level of current flowing in the induction coil 4a to a second predefined threshold current level; the controller 5 is configured to discharge the electrodes 3b in said electroactive polymer stack 3 to allow the stack to eclectically return to its original shape, if the level of current flowing in the induction coil 4a is greater than the second predefined threshold current level.
  • the metallic element 20b begins to move towards the induction coil 4a, resulting in an increase in the current flowing in the induction coil 4a so that the level of current conducted in the induction coil 4a increases to a level which is equal to, or greater than, the second predefined threshold current level.
  • the controller 5 discharges the electrodes 3b in the electroactive polymer stack 3, to allow the electroactive polymer stack 3 to expand from its compressed state to elastically return to its original shape; the expansion of the electroactive polymer stack 3 back to its original shape provides the user with tactile feedback.
  • the original shape of the electroactive polymer stack 3 is the shape which the electroactive polymer stack 3 had prior to the user applying a force to the plate element 20a.
  • the controller 5 of the assembly 200 is configured to process said variable output of the sensor 5 to determine the amount which said electroactive polymer stack has been compressed.
  • the controller 5 may be configured to determine, based on the level of current flowing in the induction coil 4a, how much the user has compressed the electroactive polymer stack 3.
  • the controller 5 may use a look-up table which was constructed during a calibration step and which contains a plurality of different current levels, and a respective compression measurement for each respective current level in the table.
  • the controller may be configured to receive from the sensor 4 the level of current flowing in the induction coil 4a and to then identify the corresponding compression measurement in the look-up table to determine the amount which the user has compressed the electroactive polymer stack 3.
  • the controller is further configured to process said afore-mentioned determined amount which the user has compressed the electroactive polymer stack 3 to determine the force which has been applied to plate element 20a of the sensor target element 2.
  • the controller 5 of the assembly 200 is configured to process said variable output of the sensor 5 to determine the force which has been applied to the plate element 20a of the sensor target element 2.
  • the controller 5 may be configured to determine, based on the level of current flowing in the induction coil 4a, how much force the user has applied to the plate element 20a of the sensor target element 2.
  • the controller 5 may use a look-up table which was constructed during a calibration step and which contains a plurality of different current levels, and a respective force measurement for each respective current level in the table.
  • the controller 5 may be configured to measure the level of current flowing in the induction coil 4a and to then identify the corresponding force measurement in the look-up table to determine the amount of force which the user has applied to the plate element 20a of the actuating member 2.
  • the controller 5 is configured to control the voltage which is applied to the electrodes 3b in the stack 3, and/or the discharge of the electrodes so that the metallic element 20b of the sensor target element 2 is moved to a predefined set- point position for the metallic element 20b.
  • the controller 5 is configured to process said variable output of the sensor 4 (which in the assembly 200 is the current flowing in the induction coil 4a) to determine the position of the metallic element 20b of the sensor target element 2; and then to compare the determined position to a predefined set-point position for the metallic element 20b.
  • the controller 5 is further configured to increase the voltage applied to the electrodes 3b in the stack 3 if the determined position of the metallic element 20b is above the predefined set-point position; and to partially or fully discharge the electrodes 3b if the determined position of the metallic element 20b is below the predefined set-point position. Increasing the voltage applied to the electrodes 3b in the stack 3 will cause the stack 3 to contract.
  • the plate element 20a will move under the influence of gravity to a lower, the metallic element 20b which is attached to the plate element 20a via the shaft 20c, will in turn move to a lower position; in another embodiment the metallic element 20b is attached (e.g. by adhesive or any other suitable attachment means) to the top of the stack 3, as the stack 3 contracts the top surface of the stack 3 will move to a lower position, and thus plate element 20a will move to a lower position, as the metallic element 20b which is attached to the plate element 20a via the shaft 20c, the metallic element 20b will in turn move to a lower position.
  • the determined position of the sensor target element 2 is above the predefined set-point position increasing the voltage applied to the electrodes 3b in the stack will move the metallic element 20b closer to the predefined set-point position.
  • discharging (partially or fully) the electrodes 3b in the stack 3 will cause the stack 3 to expand (from a previously contracted state); as the stack 3 expands the plate element 20a will be moved by the expanding stack 3 to a higher position, as the plate element 20a is moved by the expanding stack 3 to a higher position the metallic element 20b which is attached to the plate element 20a via the shaft 20c is moved to a higher position; thus if the determined position of the sensor target element 2 is below the predefined set-point position then discharging (partially or fully) will move the metallic element 20b closer to the predefined set-point position.
  • the controller 5 may be configured to process said variable output of the sensor 4 (which in the assembly 1 is the current flowing in the induction coil 4a) to determine the position of the metallic element 20b using any suitable means.
  • a calibration step is carried out wherein the level of current flowing in the induction coil 4a and the corresponding position of the metallic element 20b is recorded when no voltage is applied to the electrodes 3b in the stack 3; and the current flowing in the induction coil 4a together with the position is recorded in a memory of the controller 5; next a maximum level of voltage is applied to the electrodes 3b in the stack 3 , and the level of the current flowing in the induction coil 4a together with the position of the metallic element 20b is recorded in a memory of the controller 5.
  • a minimum position value which is the position occupied by the metallic element 20b when no voltage is applied to the stack 3, together with a minimum induction current level which is the level of current flowing in the induction coil 4a when no voltage is applied to the stack 3; a maximum position value which is the position occupied by the metallic element 20b when a maximum voltage is applied to the stack 3, together with a maximum induction current level which is the level of current flowing in the induction coil 4a when a maximum voltage is applied to the stack 3.
  • the controller is configured to use the calibrated, minimum position value, minimum induction current, level maximum position value, and maximum induction current level to determine, by interpolation, the position of the metallic element 20b from any level of current flowing in the induction coil 4a as output from the sensor 4.
  • the controller determines the position of the metallic element 20b to be correspondingly mid-way between the maximum and minim position value; in other words the controller can determine the position of the metallic element 20b to be '5mm'.
  • This embodiment is especially useful when there is a substantially linear relationship between the position of the metallic element 20b and the level of current flowing in the induction coil 4a.
  • the calibration step comprises applying a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the level of current flowing in the induction coil 4a and the corresponding position of the metallic element 20b.
  • the controller 5 is configured to use said plurality of recorded levels of current flowing in the induction coil 4a and positions of the metallic element 20b to determine, by interpolation (if necessary), the position of metallic element 20b from any level of current flowing in the induction coil 4a as output from the sensor 4.
  • a look-up take is formed during the calibration step: a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the level of current flowing in the induction coil 4a and the corresponding position of the metallic element 20b in a look-up table.
  • the resulting look-up table will comprise a plurality of different levels of current flowing in the induction coil 4a and a respective position of the metallic element 20b associated with each respective level of current.
  • the controller 5 is configured to use the look-up table to determine the position of the metallic element 20b from any level of current flowing in the induction coil 4a as output from the sensor 4.
  • the controller 5 receives the a level of current flowing in the induction coil 4a output from the sensor 4; the controller 5 then identifies the corresponding current level in the look up table; the controller 5 then identifies the position associated with said identified current level in the look-up table, as being the position which the metallic element 20b currently occupies.
  • the controller 5 would work in a similar fashion as the embodiments already described above, to detect the position of the metallic element 20b, if the sensor 4 is a capacitive sensor, a magnetic sensor or an optical sensor.
  • Figure 3a is a perspective view of an assembly 300 according to a further embodiment of the present invention.
  • Figure 3b is a cross-section view of an assembly 300.
  • Figure 3c is a perspective view of the assembly 300 showing a user applying a force to the sensor target element so as to compress the electroactive polymer stack of the assembly.
  • Figure 3d is a cross-section view of the assembly 300, when a user applies a force to the sensor target element so as to compress the electroactive polymer stack of the assembly.
  • the assembly 300 has many of the same features as the assembly
  • the assembly 300 comprises a sensor target element 2; an electroactive polymer stack 3 comprising a plurality of layers of compressible material 3a with a respective electrode 3b interposed between said layers of compressible material 3a; a sensor 4 which is configured to output a variable, wherein the value of said variable changes when the sensor target element 2 is moved relative to the sensor 4; and a controller 5 which is configured to process said variable output of the sensor 4.
  • the controller 5 is electrically connected to the electrodes 3b in the electroactive polymer stack 3.
  • the sensor 4 may take any suitable form and sensor target element 2 may take any suitable form.
  • the sensor 4 may be an inductive sensor, a capacitive sensor, a magnetic sensor or an optical sensor; the sensor target element 2 may comprise a metallic element, a magnetic element, or an optical element.
  • the sensor is an inductive sensor 4 having the same features as the inductive sensor 4 of the assembly 1 shown in Figures 1a-1c.
  • the frame 30 comprises a frame 30 comprising a plate element 30a and a metallic element 30b, and one or more shaft members 30c each of which is connected between the plate element 30a and the metallic element 30b.
  • the frame 30 comprises four shaft member 30c, however it should be understood that the frame 30 could have any number of shaft members.
  • the electroactive polymer stack 3 and sensor 4 are located within a volume defined by the frame 30, between the plate element 30a and a metallic element 30b.
  • the frame member 30 is configured to be moveable with respect to the sensor 4 so that the metallic element 30b can be moved away from the sensor 4 by applying a force to the plate element 30a to compress the electroactive polymer stack 3 between the plate element 30a and the sensor 4.
  • the metallic element 30b moves away from the induction coil 4
  • the metallic element 30b moves away from the magnetic field generated by the current conducted in said induction coil 4a
  • the reduction in eddy currents in turn leads to a decrease in the level of current conducted in the induction coil 4a.
  • the further the metallic element 30b is moved away from the induction coil 4a of the inductive sensor 4 the larger the decrease in the level of current flowing in the induction coil 4a; correspondingly, movement of the metallic element 30b towards the induction coil 4a increases the level of current flowing in the induction coil 4a.
  • the controller 5 is configured to process said variable output of the sensor 4; in other words, in this embodiment, the sensor 4 outputs the level of current flowing in its respective induction coil 4a to the controller 5, and the controller 5 is configured to process that level of current flowing in its respective induction coil 4.
  • the controller 5 is preferably configured to process the current flowing in the induction coil 4a, by comparing the level of current flowing in the induction coil 4a to a first predefined threshold current level; then the controller 5 is configured to apply a voltage to the electrodes 3b in said electroactive polymer stack 3 to cause the stack to compress if the level of current flowing in the induction coil 4a is less than a first predefined threshold current level.
  • the controller applies a voltage to the electrodes 3b in this causes the electrodes 3b to move towards one another; as the electrodes 3b move towards one another they compress the layers of flexible material 3a, thus resulting in the compression of the electroactive polymer stack 3.
  • the controller 5 applies a pulse of voltage to the electrodes 3b in the electroactive polymer stack 3, to cause the electroactive polymer stack 3 to compress.
  • the controller 5 is also configured to compare the level of current flowing in the induction coil 4a to a second predefined threshold current level, after the controller 5 has applied a voltage to the electrodes 3b which caused the electroactive polymer stack 3 to compress; and the controller 5 is preferably configured to discharge the electrodes 3b in said electroactive polymer stack 3 if the level of current is above said second predefined threshold current level.
  • the controller 5 is preferably configured to process the current flowing in the induction coil 4a, by comparing the level of current flowing in the induction coil 4a to a second predefined threshold current level; the controller 5 is configured to discharge the electrodes 3b in said electroactive polymer stack 3 to allow the stack to eclectically return to its original shape, if the level of current flowing in the induction coil 4a is greater than the second predefined threshold current level.
  • the metallic element 20b begins to move towards the induction coil 4a, resulting in an increase in the current flowing in the induction coil 4a so that the level of current conducted in the induction coil 4a increases to a level which is equal to, or greater than, the second predefined threshold current level.
  • the controller 5 discharges the electrodes 3b in the electroactive polymer stack 3, to allow the electroactive polymer stack 3 to expand from its compressed state to elastically return to its original shape; the expansion of the electroactive polymer stack 3 back to its original shape provides the user with tactile feedback.
  • the original shape of the electroactive polymer stack 3 is the shape which the electroactive polymer stack 3 had prior to the user applying a force to the plate element 30a.
  • the controller 5 of the assembly 300 is configured to process said variable output of the sensor 5 to determine the amount which said electroactive polymer stack 3 has been compressed.
  • the controller 5 may be configured to determine, based on the level of current flowing in the induction coil 4a, how much the user has compressed the electroactive polymer stack 3.
  • the controller 5 may use a look-up table which was constructed during a calibration step and which contains a plurality of different current levels, and a respective compression measurement for each respective current level in the table.
  • the controller may be configured to receive from the sensor 4 the level of current flowing in the induction coil 4a and to then identify the corresponding compression measurement in the look-up table to determine the amount which the user has compressed the electroactive polymer stack 3.
  • the controller is further configured to process said afore-mentioned determined amount which the user has compressed the electroactive polymer stack 3 to determine the force which has been applied to plate element 30a of fame 30.
  • the controller 5 of the assembly 300 is configured to process said variable output of the sensor 5 to determine the force which has been applied to the plate element 30a of the sensor target element 2.
  • the controller 5 may be configured to determine, based on the level of current flowing in the induction coil 4a, how much force the user has applied to the plate element 30a of the frame 30 of the sensor target element 2.
  • the controller 5 may use a look-up table which was constructed during a calibration step and which contains a plurality of different current levels, and a respective force measurement for each respective current level in the table.
  • the controller 5 may be configured to measure the level of current flowing in the induction coil 4a and to then identify the corresponding force measurement in the look-up table to determine the amount of force which the user has applied to the plate element 30a of the frame 30 of the sensor target element 2. [00103] In a further variation of the assembly 300, the controller 5 is configured to control the voltage which is applied to the electrodes 3b in the stack 3, and/or the discharge of the electrodes so that the metallic element 30b of the sensor target element 2 is moved to a predefined set- point position for the metallic element 30b.
  • the controller 5 is configured to process said variable output of the sensor 4 (which in the assembly 200 is the current flowing in the induction coil 4a) to determine the position of the metallic element 30b of the sensor target element 2; and then to compare the determined position to a predefined set-point position for the metallic element 30b.
  • the controller 5 is further configured to increase the voltage applied to the electrodes 3b in the stack 3 if the determined position of the metallic element 30b is above the predefined set-point position; and to partially or fully discharge the electrodes 3b if the determined position of the metallic element 30b is below the predefined set-point position. Increasing the voltage applied to the electrodes 3b in the stack 3 will cause the stack 3 to contract.
  • the plate element 30a will move under the influence of gravity to a lower, the metallic element 30b which is attached to the plate element 30a via the shaft 30c, will in turn move to a lower position; in another embodiment the metallic element 30b is attached (e.g. by adhesive or any other suitable attachment means) to the top of the stack 3, as the stack 3 contracts the top surface of the stack 3 will move to a lower position, and thus plate element 30a will move to a lower position, as the metallic element 30b which is attached to the plate element 20a via the shaft members 30c, the metallic element 30b will in turn move to a lower position.
  • the determined position of the sensor target element 2 is above the predefined set-point position increasing the voltage applied to the electrodes 3b in the stack will move the metallic element 30b closer to the predefined set-point position.
  • discharging (partially or fully) the electrodes 3b in the stack 3 will cause the stack 3 to expand (from a previously contracted state); as the stack 3 expands the plate element 30a will be moved by the expanding stack 3 to a higher position, as the plate element 30a is moved by the expanding stack 3 to a higher position the metallic element 30b which is attached to the plate element 30a via the shaft members 30c is moved to a higher position; thus if the determined position of the sensor target element 2 is below the predefined set-point position then discharging (partially or fully) will move the metallic element 30b closer to the predefined set-point position.
  • the controller 5 may be configured to process said variable output of the sensor 4 (which in the assembly 1 is the current flowing in the induction coil 4a) to determine the position of the metallic element 30b using any suitable means.
  • a calibration step is carried out wherein the level of current flowing in the induction coil 4a and the corresponding position of the metallic element 30b is recorded when no voltage is applied to the electrodes 3b in the stack 3; and the current flowing in the induction coil 4a together with the position is recorded in a memory of the controller 5; next a maximum level of voltage is applied to the electrodes 3b in the stack 3 , and the level of the current flowing in the induction coil 4a together with the position of the metallic element 30b is recorded in a memory of the controller 5.
  • a minimum position value which is the position occupied by the metallic element 30b when no voltage is applied to the stack 3, together with a minimum induction current level which is the level of current flowing in the induction coil 4a when no voltage is applied to the stack 3; a maximum position value which is the position occupied by the metallic element 30b when a maximum voltage is applied to the stack 3, together with a maximum induction current level which is the level of current flowing in the induction coil 4a when a maximum voltage is applied to the stack 3.
  • the controller is configured to use the calibrated, minimum position value, minimum induction current, level maximum position value, and maximum induction current level to determine, by interpolation, the position of the metallic element 30b from any level of current flowing in the induction coil 4a as output from the sensor 4.
  • the controller determines the position of the metallic element 30b to be correspondingly mid-way between the maximum and minim position value; in other words the controller can determine the position of the metallic element 30b to be '5mm'.
  • This embodiment is especially useful when there is a substantially linear relationship between the position of the metallic element 30b and the level of current flowing in the induction coil 4a.
  • the calibration step comprises applying a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the level of current flowing in the induction coil 4a and the corresponding position of the metallic element 30b.
  • the controller 5 is configured to use said plurality of recorded levels of current flowing in the induction coil 4a and positions of the metallic element 30b to determine, by interpolation (if necessary), the position of metallic element 30b from any level of current flowing in the induction coil 4a as output from the sensor 4.
  • a look-up take is formed during the calibration step: a plurality of different voltage levels to the electrodes 3b in the stack, and for each voltage level recording the level of current flowing in the induction coil 4a and the corresponding position of the metallic element 30b in a look-up table.
  • the resulting look-up table will comprise a plurality of different levels of current flowing in the induction coil 4a and a respective position of the metallic element 30b associated with each respective level of current.
  • the controller 5 is configured to use the look-up table to determine the position of the metallic element 30b from any level of current flowing in the induction coil 4a as output from the sensor 4.
  • the controller 5 receives the a level of current flowing in the induction coil 4a output from the sensor 4; the controller 5 then identifies the corresponding current level in the look up table; the controller 5 then identifies the position associated with said identified current level in the look-up table, as being the position which the metallic element 30b currently occupies.
  • the controller 5 would work in a similar fashion as the embodiments already described above, to detect the position of the metallic element 30b, if the sensor 4 is a capacitive sensor, a magnetic sensor or an optical sensor.
  • Figure 4a is a perspective view of an assembly 400 according to a further embodiment of the present invention.
  • Figure 4b is a cross section view of the assembly 400.
  • the assembly 400 has many of the same features as the assembly 1 shown in Figures 1a-1c and like features are awarded the same reference numbers.
  • the assembly 400 comprises an sensor target element 2; an electroactive polymer stack 3 comprising a plurality of layers of compressible material 3a with a respective electrode 3b interposed between said layers of compressible material 3a; a sensor 4 which is configured to output a variable, wherein the value of said variable changes when the sensor target element 2 is moved relative to the sensor 4; and a controller 5 which is configured to process said variable output of the sensor 4.
  • the controller 5 is electrically connected to the electrodes 3b in the electroactive polymer stack 3.
  • Figure 4b is a cross section view of the assembly 400 showing the electroactive polymer stack 3 in an expanded state; the electroactive polymer stack 3 is in the expanded state when the electrodes 3b are discharged.
  • Figure 4c is a cross-section view of the assembly 400, showing the electroactive polymer stack 3 in a compressed state; the electroactive polymer stack 3 is in the compressed state when the electrodes 3b are charged (or when a user applies a force to the sensor target element 2 which compresses the stack 3).
  • the sensor 4 may take any suitable form and sensor target element 2 may take any suitable form.
  • the sensor is an inductive sensor 4 having similar features as the inductive sensor 4 of the assembly 1 shown in Figures 1a-1c; like features are awarded the same reference numbers.
  • the sensor target element 2 comprises a plate element 40a and a metallic core element 40b which is connected to the plate element 40a so that the metallic core element 40b can move together with the plate element 40a.
  • a plurality of shaft members 40c are attached between the plate element 40a and a metallic core element 40b.
  • the metallic core element 40b is composed of ferromagnetic material (i.e. an iron core element 40b); in the assembly 400 the metallic core element 40b comprises ferromagnetic material (and more preferably the metallic core element 40b is composed of iron).
  • the assembly 400 further comprises, a tubular member 42 having a primary coil 43b, and respective first secondary coil 43a and second secondary coil 43c.
  • the primary coil 43b wrapped around a first portion of an outer surface 44 of the tubular member 42;
  • the first secondary coil 43a is wrapped around a second portion of the outer surface 44 of the tubular member 42;
  • the second secondary coil 43c is wrapped around a third portion of the outer surface 44 of the tubular member 42.
  • the metallic core element 40b is located inside the volume defined by the tubular member 42, and is located between the electroactive polymer stack 3 and an inner surface 45 of the tubular member 42, and is arranged so that it overlays the primary coil 43b and at least partially overlays the first secondary coil 43a and second secondary coil 43c.
  • the metallic core element 40b, and primary coil 43b and first secondary coil 43a and second secondary coil 43c act like a transformer. Alternating current flows in the primary coil 43b (most preferably an current source provides a current of constant amplitude to the primary coil 43b). As a result of the alternating current flowing in the primary coil 43b magnetic flux is created; this magnetic flux is coupled by the metallic core element 40b to both the first secondary coil 43a and second secondary coil 43c.
  • the metallic core element 40b If, however, the metallic core element 40b is moved (e.g. by way of applying a force to the plate element 40a, or by compressing the stack 3 by applying a voltage to the electrodes 3b in the stack) such the metallic core element 40b overlays a larger proportion of the second secondary coil 43c than the first secondary coil 43a, as shown in Figure 4c, then the metallic core element 40b will couple more magnetic flux to the second secondary coil 43c and will couple less magnetic flux to the first secondary coil 43a.
  • the metallic core element 40b will couple more magnetic flux to the second secondary coil 43c and will couple less magnetic flux to the first secondary coil 43a.
  • the level of current induced in the second secondary coil 43c will be higher than the level of current that is induced in the first secondary coil 43a; in this case the difference between the induced current in the first secondary coil 43a and the induced current in the second secondary coil 43c will be non-zero. It should be understood that the difference between the induced current in the first secondary coil 43a and the induced current in the second secondary coil 43c will be either positive or negative; the direction in which the metallic core element 40b has been moved can be determined based on whether the different is positive or negative.
  • the metallic core element 40b Conversely, if the metallic core element 40b is moved such the metallic core element 40b overlays a larger proportion of the first secondary coil 43a than the second secondary coil 43c, then the metallic core element 40b will couple more magnetic flux to the first secondary coil 43a and will couple less magnetic flux to the second secondary coil 43c. As a result the level of current induced in the first secondary coil 43a will be higher than the level of current that is induced in the second secondary coil 43c; in this case the difference between the induced current in the first secondary coil 43a and the induced current in the second secondary coil 43c will also be non-zero.
  • the difference between the induced current in the first secondary coil 43a and the induced current in the second secondary coil 43c will be either positive or negative; the direction in which the metallic core element 40b has been moved can be determined based on whether the different is positive or negative.
  • the sensor 4 is configured to measure the level of current (induced current) flowing in the first secondary coil 43a and the second secondary coil 43c.
  • the variable output of the sensor 4 are the levels of current (induced current) flowing in each of the first secondary coil 43a and the second secondary coil 43c.
  • a portion of the electroactive polymer stack 3 is located within a volume defined by the tubular member 42.
  • the electroactive polymer stack 3 is located between the plate element 40a and the sensor 4.
  • a voltage is applied to the electrodes 3b in the electroactive polymer stack 3 to cause the stack 3 to become compressed, as shown in Figure 4c; when the stack 3 compresses, the plate member 40a moves towards the sensor 4 so the metallic core element 40b, which is fixed to the plate member 40a via the plurality of shaft members 40c, moves such the metallic core element 40b overlays a larger proportion of the second secondary coil 43c than the first secondary coil 43a.
  • the level of current induced in the second secondary coil 43c will be higher than the level of current that is induced in the first secondary coil 43a. Accordingly by measuring the difference between the level of current induced in the second secondary coil 43c and the level of current that is induced in the first secondary coil 43a, it is possible to determine the position of the plate member 40a.
  • the stack 3 will begin to expand from its compressed state, to elastically return to its original shape.
  • the plate member 40a moves away from the sensor 4 so the metallic core element 40b, which is fixed to the plate member 40a via the plurality of shaft members 40c, moves such the metallic core element 40b overlays a decreasing proportion of the second secondary coil 43c and a correspondingly increasing proportion of the first secondary coil 43a.
  • the level of current induced in the second secondary coil 43c will begin to decrease and the level of current that is induced in the first secondary coil 43a will begin to increase.
  • the metallic core element 40b will come to rest midway between the first secondary coil 43a and second secondary coil 43c, as shown in Figure 4b, at which point equal levels of current will be induced in the first secondary coil 43a and second secondary coil 43c.
  • the controller 5 is configured to process said variable output of the sensor 4; in other words, in this embodiment, the controller 5 is configured to process the level of current (induced current) flowing in the first secondary coil 43a and the level of current (induced current) flowing in the second secondary coil 43c, which are output from the sensor 4.
  • the controller 5 is preferably configured to process the level of current (induced current) flowing in the first secondary coil 43a and the level of current (induced current) flowing in the second secondary coil 43c, by first determining the difference between the level of current (induced current) flowing in the first secondary coil 43a and the level of current (induced current) flowing in the second secondary coil 43c.
  • the controller 5 is preferably configured to determine, based on the difference, the position of the plate member 40a.
  • the controller 5 is further configured to adjust the voltage which is applied to the electrodes 3b in the stack 3 so that the plate member 40a is moved to a predefined set- point position.
  • the first secondary coil and the second secondary coil of the assembly 400 are connected in series oppositions, whereby a zero (or substantially zero) differential current may be obtained from this output; in this case the controller 5 does not need to be configured to determine the difference between the level of current (induced current) flowing in the first secondary coil 43a and the level of current (induced current) flowing in the second secondary coil 43c because the output of the sensor 4 will be the difference between the level of current (induced current) flowing in the first secondary coil 43a and the level of current (induced current) flowing in the second secondary coil 43c; accordingly in this variation the controller 5 is preferably configured to determine, based on the difference which is output for the sensor 4, the position of the plate member 40a.
  • the controller 5 is preferably configured to determine, based on the difference, the position of the plate member 40a, using a look-up table which was constructed during a calibration step and which contains a plurality of difference values (i.e. a plurality of values for the difference between the level of current (induced current) flowing in the first secondary coil 43a and the level of current (induced current) flowing in the second secondary coil 43), and a respective position associated with each respective difference value in the look-up table.
  • a look-up table which was constructed during a calibration step and which contains a plurality of difference values (i.e. a plurality of values for the difference between the level of current (induced current) flowing in the first secondary coil 43a and the level of current (induced current) flowing in the second secondary coil 43), and a respective position associated with each respective difference value in the look-up table.
  • the controller may be configured to receive, the level of current (induced current) flowing in the first secondary coil 43a and the level of current (induced current) flowing in the second secondary coil 43c, from the sensor 4; determine the difference between the level of current (induced current) flowing in the first secondary coil 43a and the level of current (induced current) flowing in the second secondary coil 43c; identify the difference value in the look-up table which corresponds to the determined difference; and then identify the position associated with said identified difference value in the look-up table.
  • the controller 5 is further configured to compared the identified position with a predefined set-point position; and to adjust the voltage applied to the electrodes 3b in the electroactive polymer stack 3, and/or partially or fully discharge the electrodes 3b in the electroactive polymer stack 3 so that the plate member 40a is moved closer to the predefined set-point position. For example, if the identified position is above the predefined set-point position then the controller 5 will increase the voltage which is applied to the electrodes 3b in the electroactive polymer stack 3 to cause the stack 3 to compress further, thereby moving the plate member 40a to a lower position and thus closer to the predefined set-point position.
  • the controller 5 will discharge the electrodes 3b in the electroactive polymer stack 3 to cause the stack 3 to expand, thereby moving the plate member 40a to a higher position and thus closer to the predefined set-point position
  • the electroactive polymer stack 3 can be compressed between the plate element 40 and the sensor 4 by applying a force to the plate element 40a to move the plate element 40a towards the sensor 4 (e.g. the user can apply a pressing force to the plate element 40).
  • a force to the plate element 40a to move the plate element 40a towards the sensor 4 (e.g. the user can apply a pressing force to the plate element 40).
  • the controller 5 is preferably configured to process the level of current (induced current) flowing in the second secondary coil 43c, which is output by the sensor 4, by, by comparing the levels of current flowing in the second secondary coil 43c to a first predefined threshold current level.
  • the controller 5 is configured to apply a voltage to the electrodes 3b in said electroactive polymer stack 3 to cause the stack to compress if the level of current flowing in the second secondary coil 43c is greater than first predefined threshold current level.
  • the controller applies a voltage to the electrodes 3b in said electroactive polymer stack this causes the electrodes 3b to move towards one another; as the electrodes 3b move towards one another they compress the layers of flexible material 3a, thus resulting in the compression of the electroactive polymer stack 3.
  • the controller 5 applies a pulse of voltage to the electrodes 3b in the electroactive polymer stack 3, to cause the electroactive polymer stack 3 to compress.
  • the controller is also preferably to compare the level of current flowing in the first secondary coil 43a, which is output by the sensor 4, to a second predefined threshold current level, after the controller 5 has applied a voltage to the electrodes 3b which caused the electroactive polymer stack 3 to compress.
  • the controller 5 is preferably configured to discharge the electrodes 3b in said electroactive polymer stack 3 if the level of current in the first secondary coil 43a is above said second predefined threshold current level.
  • the controller 5 is preferably configured to process the current flowing in the first secondary coil 43arada by comparing the level of current flowing in the first secondary coil 43a, which is output from the sensor 4, to a second predefined threshold current level; the controller 5 is configured to discharge the electrodes 3b in said electroactive polymer stack 3 to allow the stack to eclectically return to its original shape, if the level of current flowing in the first secondary coil 43a, is greater than the second predefined threshold current level.
  • the controller 5 applies a voltage to the electrodes 3b in the electroactive polymer stack 3, to cause the electroactive polymer stack 3 to compress. Most preferably the controller 5 applies a pulse of voltage to the electrodes 3b in the electroactive polymer stack 3, to cause the electroactive polymer stack 3 to compress.
  • the compression of the electroactive polymer stack 3 provides the user with tactile feedback.
  • the controller 5 discharges the electrodes 3b in the electroactive polymer stack 3, to allow the electroactive polymer stack 3 to expand from its compressed state to elastically return to its original shape; the expansion of the electroactive polymer stack 3 back to its original shape provides the user with tactile feedback.
  • the original shape of the electroactive polymer stack 3 is the shape which the electroactive polymer stack 3 had prior to the user applying a force to the plate element 40a.
  • the senor 4 could be configured to measure the current in only one of the first secondary coil 43a or second secondary coil 43c. In such a case the variable output of the sensor 4 would be the level of current conducted in that one secondary coil. The controller 5 would then also apply the voltage to the electrodes 3b in the electroactive polymer stack 3 or discharge the electrodes 3b in the electroactive polymer stack 3 depending on the level of current output from the sensor 4.
  • the controller 5 would be configured to apply the voltage to the electrodes 3b in the electroactive polymer stack 3 if the level of current in the second secondary coil 43c, as output from the sensor 4, is above a first threshold current level; and the controller 5 would be configured to discharge the electrodes 3b in the electroactive polymer stack 3, after having applied a voltage to said electrodes 3b, if the level of current in the second secondary coil 43c, as output from the sensor 4, drops below a second threshold current level.
  • the controller 5 would be configured to apply the voltage to the electrodes 3b in the electroactive polymer stack 3 if the level of current in the first secondary coil 43a, as output from the sensor 4, is below a first threshold current level; and the controller 5 would be configured to discharge the electrodes 3b in the electroactive polymer stack 3, after having applied a voltage to said electrodes 3b, if the level of current in the first secondary coil 43a, as output from the sensor 4, increases above a second threshold current level.
  • the controller 5 of the assembly 400 may be configured to process said variable output of the sensor 5 to determine the amount which said electroactive polymer stack 3 has been compressed.
  • the controller 5 may be configured to determine, based on the level of current flowing in at least one of the first secondary coil 43a or second secondary coil 43c (as output from the sensor 4), how much the user has compressed the electroactive polymer stack 3.
  • the controller 5 may use a look-up table which was constructed during a calibration step and which contains a plurality of different current levels, and a respective compression measurement for each respective current level in the table.
  • the controller 5 may be configured to receive the level of current flowing in at least one of the first secondary coil 43a and/or second secondary coil 43c from the sensor 4 and to then identify the corresponding compression measurement in the look-up table to determine the amount which the user has compressed the electroactive polymer stack 3.
  • the controller 5 is further configured to process said afore-mentioned determined amount which the user has compressed the electroactive polymer stack 3 to determine the force which has been applied to plate element 40a.
  • the controller 5 of the assembly 400 is configured to process said variable output of the sensor 4 to determine the force which has been applied to the plate element 40a of the sensor target element 2.
  • the controller 5 may be configured to determine, based on the level of current flowing in at least one of the first secondary coil 43a and/or second secondary coil 43c (as output from the sensor 4), how much force the user has applied to the plate element 40a of the sensor target element 2.
  • the controller 5 may use a look-up table which was constructed during a calibration step and which contains a plurality of different current levels, and a respective force measurement for each respective current level in the table.
  • the controller 5 may be configured receive the level of current flowing in at least one of the first secondary coil 43a and/or second secondary coil 43c from the sensor 4 and to then identify the corresponding force measurement in the look-up table to determine the amount of force which the user has applied to the plate element 40a of the sensor target element 2.
  • Figure 5a is a perspective view of an assembly 500 according to a further embodiment of the present invention.
  • the assembly 500 has many of the same features as the assembly 1 shown in Figures 1a-1c and like features are awarded the same reference numbers.
  • Figure 5b is a perspective view of the assembly 500 when a user applies a force to the sensor target element of the assembly 500 so as to compress one or more of the electroactive polymer stacks of the assembly.
  • the assembly 500 comprises a sensor target element 2; a plurality of electroactive polymer stacks 3 each of which comprises a plurality of layers of compressible material 3a with a respective electrode 3b interposed between said layers of compressible material 3a; and a plurality of sensors 4, each sensor 4 being associated with a respective electroactive polymer stack 3, and each sensor 4 is configured to output a variable, wherein the value of said variable changes when the sensor target element 2 is moved relative to that sensor 4; and a controller 5 which is configured to process said variable output of the sensor 4.
  • each sensor 4 is associated with a respective electroactive polymer stack 3 in that each electroactive polymer stack 3 is mounted on a respective sensor 4.
  • the assembly 500 comprises four sensors 4 and four electroactive polymer stacks 3; however it should be understood that the assembly 500 could have any number of sensors 4 and fow electroactive polymer stacks 3, although it is preferable that the number of number of sensors 4 is equal to the number of electroactive polymer stacks 3 so that each electroactive polymer stack 3 can be associated with a respective sensor 4.
  • the controller 5 is electrically connected to the electrodes 3b in one or more of the electroactive polymer stacks 3. Most preferably the controller 5 is electrically connected to the electrodes 3b in all of the electroactive polymer stacks 3.
  • each of the sensors 4 may take any suitable form and sensor target element 2 may take any suitable form.
  • each of the sensors 4 may be an inductive sensor, a capacitive sensor, a magnetic sensor or an optical sensor; the sensor target element 2 may comprise a metallic element, a magnetic element, or an optical element.
  • each of the sensors 4 is an inductive sensor 4 each having the same features as the inductive sensor 4 of the assembly 1 shown in Figures 1a-1c.
  • the sensor target element 2 comprises a metallic layer 2a and a layer of another material 2b which is mounted on the metallic layer 2a.
  • the layer of another material 2b will be referred to hereafter as the top layer 2b.
  • the top layer 2b comprises glass or polymer (or any other suitable material, such as material which is suitable for forming a touchscreen). It should be understood that the top layer 2b is an optional feature. Both the metallic layer 2a and the top layer 2b overlay all of the plurality of electroactive polymer stacks 3.
  • the controller 5 is configured to process said variable output of each of the sensors 4; in other words, in this embodiment, each sensor 4 outputs the level of current flowing in its respective induction coil 4a to the controller 5, and the controller 5 is configured to process those levels of current which it receives from the sensor 4. Specifically, the controller 5 is configured to process those levels of current which it receives from the sensor 4 to determine a location on the sensor target element 2 where the user has applied a force.
  • the controller 5 is configured to process said levels of current which it receives from each respective sensor 4 to determine the amount which each respective electroactive polymer stack 3 which is associated with that sensor 4, has been compressed.
  • the controller 5 may use a first look-up table which was constructed during a calibration step and which contains a plurality of different current levels, and a respective compression measurement for each respective current level in the table.
  • the controller 5 may be configured to receive from each sensor 4 the level of current flowing in the induction coil 4a of that sensor 4 and to then identify the corresponding compression measurement in the first look-up table to determine the amount which the user has compressed the electroactive polymer stack 3 which is associated with that sensor 4.
  • the controller 5 may use a second look-up table which was constructed during a calibration step, to determine, based on said afore mentioned determined amount which each electroactive polymer stack 3 has been compressed, a position on the sensor target element 2 (more preferable a position on the top layer 2b of the sensor target element 2) where the user has applied a force.
  • Said second look-up table preferable contains a plurality of sets of compression measurements (each set containing a compression measurement from each of the plurality of electroactive polymer stacks 3 - in other words since in this exemplary embodiment the assembly 500 comprises four electroactive polymer stacks 3 each respective set of compression measurements will comprise four compression measurements, one for each electroactive polymer stacks 3), and a respective position coordinates (e.g.
  • each respective position coordinate representing a respective position on the sensor target element 2 (more preferably each respective position coordinate representing a respective position on the top layer 2b of the sensor target element 2) being associated with each set of compression measurement in the look-up table.
  • the controller 5 identifies the corresponding set of compression measurements in the second look up table and the position coordinate associated with said set of compression measurements in the second look up table defines the position on the sensor target element 2 (more preferable a position on the top layer 2b of the sensor target element 2) where the user has applied a force.
  • any of the above-mentioned assembly embodiments could be part of a button assembly, the tactile feedback provided by the assembly embodiment functioning to indicate to the user that they have provided sufficient force to the button to press the button, and/or to indicate to the user that they have removed force from the button and that the button is no longer pressed.
  • the sensor target element 2 may be attached (e.g. by adhesive or any other suitable attachment means) to the electroactive polymer stack 3. Most preferably the sensor target element 2 is attached (e.g. by adhesive or any other suitable attachment means) to a top (such as a top surface) of the electroactive polymer stack 3.

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  • Measurement Of Length, Angles, Or The Like Using Electric Or Magnetic Means (AREA)

Abstract

L'invention concerne un ensemble comprenant un élément cible de capteur ; une pile de polymères électroactifs comprenant une pluralité de couches de matériau compressible avec une électrode respective interposée entre lesdites couches ; un capteur qui est configuré pour délivrer en sortie une variable, la valeur de ladite variable changeant lorsque l'élément cible de capteur est déplacé par rapport au capteur ; un dispositif de commande qui est configuré pour traiter ladite variable délivré en sortie par le capteur ; ledit élément cible de capteur étant conçu pour coopérer avec ladite pile de sorte que l'application d'une force à l'élément cible de capteur provoque la déformation de la pile et le déplacement de l'élément cible de capteur par rapport au capteur, et/ou de sorte que la déformation de la pile en appliquant une tension aux électrodes dans la pile de polymères électroactifs ou en déchargeant les électrodes dans la pile de polymères électroactifs amènera l'élément cible de capteur à se déplacer par rapport au capteur.
PCT/IB2020/054557 2020-05-14 2020-05-14 Ensemble comprenant une pile de polymères électroactifs, un élément cible de capteur, un capteur et un dispositif de commande Ceased WO2021229272A1 (fr)

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PCT/IB2020/054557 WO2021229272A1 (fr) 2020-05-14 2020-05-14 Ensemble comprenant une pile de polymères électroactifs, un élément cible de capteur, un capteur et un dispositif de commande

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PCT/IB2020/054557 WO2021229272A1 (fr) 2020-05-14 2020-05-14 Ensemble comprenant une pile de polymères électroactifs, un élément cible de capteur, un capteur et un dispositif de commande

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WO2021229272A1 true WO2021229272A1 (fr) 2021-11-18

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3278375A1 (fr) * 2015-03-31 2018-02-07 Koninklijke Philips N.V. Dispositif actionneur ou capteur à base de polymère électroactif
DE102017204574A1 (de) * 2017-03-20 2018-09-20 Robert Bosch Gmbh Anzeigeelement und Vorrichtung zum Betreiben desselben
EP3432372A1 (fr) * 2017-07-20 2019-01-23 Koninklijke Philips N.V. Structure d'actionneur et son procédé d'actionnement
WO2020127580A1 (fr) * 2018-12-18 2020-06-25 Motherson Innovations Company Ltd. Dispositif transducteur à polymère électroactif et fabrication

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3278375A1 (fr) * 2015-03-31 2018-02-07 Koninklijke Philips N.V. Dispositif actionneur ou capteur à base de polymère électroactif
DE102017204574A1 (de) * 2017-03-20 2018-09-20 Robert Bosch Gmbh Anzeigeelement und Vorrichtung zum Betreiben desselben
EP3432372A1 (fr) * 2017-07-20 2019-01-23 Koninklijke Philips N.V. Structure d'actionneur et son procédé d'actionnement
WO2020127580A1 (fr) * 2018-12-18 2020-06-25 Motherson Innovations Company Ltd. Dispositif transducteur à polymère électroactif et fabrication

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