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WO2025099649A1 - Dispositif et appareil de détection de force - Google Patents

Dispositif et appareil de détection de force Download PDF

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Publication number
WO2025099649A1
WO2025099649A1 PCT/IB2024/061066 IB2024061066W WO2025099649A1 WO 2025099649 A1 WO2025099649 A1 WO 2025099649A1 IB 2024061066 W IB2024061066 W IB 2024061066W WO 2025099649 A1 WO2025099649 A1 WO 2025099649A1
Authority
WO
WIPO (PCT)
Prior art keywords
force
sensing device
floating element
base
sensing
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.)
Pending
Application number
PCT/IB2024/061066
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English (en)
Inventor
Michael Alexander WOOD
David Charles Rhodes
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.)
Real Instruments Ltd
Original Assignee
Real Instruments Ltd
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
Priority claimed from AU2023903575A external-priority patent/AU2023903575A0/en
Application filed by Real Instruments Ltd filed Critical Real Instruments Ltd
Publication of WO2025099649A1 publication Critical patent/WO2025099649A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/0052—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes measuring forces due to impact
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L1/00—Measuring force or stress, in general
    • G01L1/04—Measuring force or stress, in general by measuring elastic deformation of gauges, e.g. of springs
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01L—MEASURING FORCE, STRESS, TORQUE, WORK, MECHANICAL POWER, MECHANICAL EFFICIENCY, OR FLUID PRESSURE
    • G01L5/00—Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
    • G01L5/0061—Force sensors associated with industrial machines or actuators
    • G01L5/0076—Force sensors associated with manufacturing machines
    • G01L5/008—Force sensors integrated in an article or a dummy workpiece

Definitions

  • the present invention relates to a force-sensing device. More particularly, but not exclusively, it relates to a force-sensing apparatus, which may incorporate some number of force-sensing devices, adapted to simulate an item of many to be subjected to bulk materials handling, transportation, and/or storage operations, to help determine impact and load forces imparted on the item during such operations. More particularly, but not exclusively, the force-sensing apparatus may determine additional environmental conditions to which it is subjected. In particular, although not solely, the force sensing apparatus simulates, by way of shape and weight, an apple, avocado, or pear.
  • strain gauges and similar sensors experience a change in resistance when deformed, and force can be calculated based on this change in resistance.
  • Another method is to indirectly calculate force by deriving it from acceleration, for example as calculated by an accelerometer or inertial measurement unit.
  • known force-sensing techniques have disadvantages especially when incorporated into a miniaturised force sensing arrangement.
  • Acceleration-based force sensing does not necessarily have temperature sensitivity problems to the same extent, but it is wholly unsuitable for measuring certain types of forces. For example, crushing forces may produce no (or minimal) acceleration that can be detected by the sensor.
  • one known technique is to insert a sensing apparatus in the shape of a piece of fruit (e.g. an apple) into the post-harvest process alongside real fruit and to allow data to be continuously collected by the apparatus.
  • a sensing apparatus in the shape of a piece of fruit (e.g. an apple) into the post-harvest process alongside real fruit and to allow data to be continuously collected by the apparatus.
  • acceleration-based force sensing is used for this purpose, but the resulting readings are known to be at best only loosely indicative of the actual forces the real fruit are experiencing.
  • An example of such an apparatus is described in US Patent No. 4,745,564.
  • the apples may be subject to a substantial temperature range (such as from 35 degrees Celsius at harvest to 4 degrees Celsius in a cool store) the thermal range that a sensing apparatus needs to accommodate and provide accurate readings over, is large. There is hence a tension between reducing the sensor size to provide compact design and granularity of force readings on the surface of the faux apple and the adverse effects of substantial temperature range in providing accurate force recordings over a substantial duration of time.
  • a substantial temperature range such as from 35 degrees Celsius at harvest to 4 degrees Celsius in a cool store
  • the invention broadly comprises a force-sensing device comprising: a floating element presented to be subjected to an external force; a base; a shear spring surrounding the floating element or the base, the shear spring being located intermediate of the floating element and the base and connecting the floating element to the base in a manner to transfer the external force to the base as a shear force, one or more non-contact displacement sensors located on a sensor-mounting surface which is mounted to or forms part of the base and is situated beneath the floating element with a gap therebetween, the displacement sensors being configured to each sense the displacement of a respective part of the floating element, in response to the external force, relative the base in the shear force direction.
  • the shear spring continuously surrounds the floating element or the base.
  • the shear spring forms a waterproof seal between the floating element and the base.
  • the shear spring discontinuously surrounds the floating element or the base, such that the shear spring is present at three or more spaced apart regions intermediate of the floating element and the base.
  • the floating element is nested within the base, and the shear spring surrounds the floating element.
  • the base is nested within the floating element, and the shear spring surrounds the base.
  • the shear spring follows a serpentine path between the floating element and the base.
  • the shear spring is held under compression between the floating element and the base.
  • stiffness of the shear spring is at least five times higher in a lateral direction than in the shear force direction. According to another aspect, the shear spring is less than 10 mm in lateral thickness.
  • the force-sensing device further comprises a contact element integral with or engaged with the floating element, the contact element extending out from the floating element in a normal direction and comprising a contact surface for receiving the external force.
  • the contact element has a substantially triangular outline.
  • the contact surface of the contact element is convex.
  • the contact surface of the contact element is concave.
  • the floating element comprises one or more engagement features that engage the contact element.
  • the one or more engagement features are cavities that receive corresponding pegs of the contact element.
  • the contact element is releasably engageable with the floating element.
  • the base further comprises a flange.
  • the contact element further comprises a lip which bears on the flange when the contact element and the floating element are sufficiently displaced, thus providing an upper limit to the displacement and hence the force that is measurable.
  • the shear spring comprises an elastomer.
  • the sensor-mounting surface is a circuit board to which the one or more displacement sensors are electrically connected.
  • the one or more displacement sensors are at least two displacement sensors.
  • the one or more displacement sensors are at least three displacement sensors arranged nonlinearly such that a point of application of the external force on the floating element can be calculated based on a combination of displacement measurements.
  • the displacement sensors are three displacement sensors in an equilateral triangular arrangement about a central axis.
  • the one or more displacement sensors are noncontact sensors.
  • the one or more displacement sensors are MEMS sensors.
  • the one or more displacement sensors are optica l/laser sensors.
  • the one or more displacement sensors are capacitive or inductive sensors.
  • the floating element, the base, and the shear spring are all concentric.
  • the force-sensing device is substantially triangular in shape.
  • the force-sensing device spans less than 100 mm in any dimension.
  • the force-sensing device spans less than 60 mm in any dimension. According to another aspect, the ratio of height to lateral bounding diameter of the force-sensing device is one third or less.
  • the invention broadly comprises a force-sensing apparatus comprising: a plurality of force-sensing devices, the force-sensing devices having their bases connected together, wherein the plurality of force-sensing devices can each independently measure external force applied thereto.
  • the plurality of force-sensing devices are arranged in a tessellated manner so as to present a force measurement surface substantially without gaps.
  • the force measurement surface is substantially spherical.
  • the force measurement surface is formed by contact surfaces of the force-sensing devices, the contact surfaces being predominantly convex but some of the contact surfaces being at least partially concave.
  • the plurality of force-sensing devices each have a unique orientation.
  • the force-sensing apparatus further comprises a frame which mounts the bases of the force-sensing devices.
  • the frame has the shape of a polyhedron.
  • the frame substantially has the shape of a deltahedron.
  • the frame substantially has the shape of an icosahedron.
  • the frame is at least partially hollow. According to another aspect, the frame comprises a plurality of faces each having a recess within which one of the force-sensing devices is seated.
  • the force-sensing apparatus is sized and shaped to mimic a type of fruit.
  • the type of fruit is an apple.
  • the invention broadly comprises a force-sensing device comprising: an inner element having an exterior interfacing wall; an outer element having an interior interfacing wall within which the inner element is nested; a shear spring disposed between the exterior interfacing wall and the interior interfacing wall so as to interface between the inner element and the outer element, the shear spring being a conforming elastic layer; and one or more non-contact displacement sensors, wherein one of the inner element and the outer element is a base and the other is a floating element, with an external force applied to the floating element causing shear motion with respect to the base as governed by elastic shear deformation of the conforming elastic layer; and wherein the one or more displacement sensors are located on a sensor-mounting surface which is mounted to or forms part of the base and is situated beneath the floating element with a gap therebetween, the displacement sensors being positioned so as to measure displacement of the floating element, such that the displacement measured facilitates calculation of the external force applied to the floating element according to precharacterised elastic properties of the conforming elastic layer.
  • the inner element is the base and the outer element is the floating element.
  • the outer element is the base and the inner element is the floating element.
  • the exterior interfacing wall and the interior interfacing wall have complementary serpentine profiles.
  • Figure 1A shows a front exploded perspective view of a force-sensing device
  • Figure 1 B shows a rear exploded perspective view of the force-sensing device
  • Figure 2A shows a top view of the force-sensing device
  • Figure 2B shows a side cross-sectional view of the force-sensing device
  • Figure 3A shows a bottom view of the force-sensing device
  • Figure 3B shows a side view of the force-sensing device
  • Figure 4A shows a simplified side cross-sectional view of the shear spring
  • Figure 4B shows a simplified perspective view of the floating element and its axes of motion
  • Figure 4C shows a simplified side cross-sectional view of the shear spring with multiple concentric sections
  • Figure 4D shows a simplified perspective view of the shear spring with multiple stacked sections
  • Figure 5A shows a perspective view of a force-sensing apparatus
  • Figure 5B shows a perspective view of a frame of the force-sensing apparatus
  • Figure 5C shows an exploded view of the force-sensing apparatus
  • Figure 6A shows an exploded view of the frame and an individual force-sensing device with its contact element
  • Figure 6B shows a perspective view of the force-sensing apparatus with contact elements
  • Figure 6C shows an exploded view of the force-sensing apparatus with contact elements.
  • a force-sensing device 10 (and a force-sensing apparatus 30). More clearly shown in Figures 1A-3B, the force-sensing device 10 comprises a floating element 12, a base 14, and a shear spring 16 located intermediate of the floating element 12 and the base 14.
  • the force-sensing device 10 is used to determine the force between the floating element 12 and the base 14.
  • the base 14 may be mounted to or be part of an object and the floating element 12 is presented to be subjected to an external force, which is to be measured.
  • the shear spring 16 connects the floating element 12 to the base 14 in a manner to transfer the external force acting on the floating element 12 to the base 14 as a shear force.
  • the shear spring 16 allows the base 14 and the floating element 12 to displace in a limited manner relative each other in the shear direction. The displacement is resisted in a spring-like manner by the shear spring 16.
  • the force-sensing device 10 further comprises one or more non-contact displacement sensors 20 to each sense the displacement of a respective part of the floating element 12, in response to the external force, relative the base 14 in the shear force direction.
  • the displacement measured facilitates calculation of the external force applied to the floating element 12 according to pre-characterised elastic properties of the shear spring 16.
  • this reversed configuration may lead to a larger overall size of the force-sensing device 10.
  • the shear spring 16 surrounds either the floating element 12 or the base 14, depending on which one is the inner element.
  • the preferred configuration of the floating element 12 as the inner element will herein be assumed, but it will be appreciated that features as described may be adapted for the reversed configuration.
  • a key benefit of using a shear spring arrangement as described above, as opposed to a traditional axial spring arrangement for example, is that expansion or contraction of the components due to changes in temperature will not cause as much distortion in the direction that displacement is measured in. This means that error in the measurement of the external force due to thermal effects is less significant, improving the accuracy of the forcesensing device 10.
  • the force-sensing device 10 has a span of less than 100 mm in any dimension (i.e. its bounding sphere has a diameter of less than 100 mm), and more preferably has a span of less than 60 mm in any dimension.
  • Such a force-sensing device 10 may be considered a "miniature" force-sensing device.
  • the ratio of height to width of the force-sensing device 10 may also influence the temperature response. In general, a greater height relative to width will lessen the temperature response and thus reduce error. However, this must be balanced against the desire to keep the force-sensing device 10 compact and easily mounted for practical use, for which a thinner shape (i.e. greater width relative to height) may be more desirable. Other factors such as the stiffness of the shear spring 16 and the maximum rated force may also be relevant in the selection of this ratio.
  • the height of the force-sensing device 10 is smaller than the lateral bounding diameter, and preferably the ratio of height to bounding diameter is one third or less, preferably at least one seventh. In a preferred example, the ratio is approximately one fifth.
  • the shear spring 16 is of a thin-walled shape. In cross section along its path it may be rectangular in shape, preferably substantially thinner than it is tall.
  • the shear spring 16 is positioned between an exterior interfacing wall 13 of the floating element 12 and an interior interfacing wall 15 of the base 14.
  • the shear spring is connected (preferably mechanically, thermally and/or chemically bonded to the exterior interfacing wall 13 of the floating element 12 and an interior interfacing wall 15 of the base 14.
  • the shear spring 16 may be considered a conforming elastic layer, in that it conforms to the shape of the exterior interfacing wall 13 and the interior interfacing wall 15.
  • the walls Preferably have complementary shape such that the conforming elastic layer has approximately constant lateral thickness, as shown in Figure 2A.
  • the shear spring is preferably compressed between them (i.e. between the exterior interfacing wall 13 and the interior interfacing wall 15). This may be achieved by way of a press fit for example. This may increase the friction with the walls which helps to better transfer shear forces.
  • the interface of the shear spring 16 with the walls may also be keyed, which may also serve to improve retention.
  • the lateral thickness of the shear spring 16 is less than 10 mm at any location, and more preferably less than 6 mm, which may assist in limiting the maximum displacement due to shear deformation. This may allow the force-sensing device 10 to be smaller in height, and thus more compact.
  • the shear spring 16 preferably follows a serpentine path between the floating element 12 and the base 14, which can be facilitated by the exterior interfacing wall 13 and the interior interfacing wall 15 having complementary serpentine profiles.
  • This serpentine shape increases the contact surface area, which improves bond strength and retention.
  • the serpentine path increases the operative length of the shear spring. This helps distribute the shear stress to avoid shear stress overloading which might otherwise cause the shear spring to separate from the base or floating element. By allowing deformation in multiple directions, the serpentine path may also better distribute stress including that which might arise from thermal expansion/contraction, as well as improve absorption of vibrations. This helps to protect the shear spring 16 from damage and increase its lifespan.
  • various other shapes may also be suitable.
  • the shear spring 16 continuously surrounds the floating element 12, i.e. it is formed as a continuous band without gaps.
  • the shear spring 16 may discontinuously surround the floating member 12 such that there is at least one gap. If there is more than one gap, then the shear spring 16 may comprise of multiple sections, preferably equally spaced. Minimising the size of the gaps can assist in providing desirable properties of the force-sensing device 10, for example minimising the temperature response and protecting against water ingress.
  • the shear spring 16 is continuous, it preferably forms a waterproof seal between the floating element 12 and the base 14.
  • the shear spring 16 comprises an elastomer, for example a silicone- based rubber.
  • the elastomer may be one with room-temperature vulcanizing properties, which may allow for easier fabrication of the shear spring 16.
  • the elastomer is preferably a hyper elastic material, in that it can undergo a large strain while still returning to its original shape and maintaining its mechanical properties.
  • the floating element 12 may comprise one or more engagement features 22, for example cavities as shown. These engagement features 22 allow for mounting of a contact element which will later be described in more detail. They do not otherwise affect the function of the floating element 12, which may alternatively have some other surface configuration.
  • the base 14 may comprise a flange 24.
  • the flange 24 may assist with mounting the force-sensing device 10, but it may also serve a force-limiting function in combination with the contact element, as will later be described in more detail.
  • a triangular shape is useful for efficient tessellation of multiple force-sensing devices 10, as will subsequently be described. It also facilitates the positioning of the displacement sensors 20 in a preferred triangular configuration as will be described.
  • the shape of the floating element 12, the base 14, and the shear spring 16 all correspond to the overall shape of the force-sensing device 10, so as to help reduce the overall size and material use.
  • the floating element 12 could alternatively have a different shape (e.g. circular) from the base 14 (e.g. square).
  • the floating element 12, the base 14, and the shear spring 16 have at least in part a concentric relationship.
  • Figure 4A shows a simplified representation of how the shear spring 16 deforms as a result of the external force, and how this results in a measurable displacement of the floating element 12.
  • the shear spring 16 undergoes an elastic, shear deformation which corresponds to the displacement Ax of the floating element 12.
  • the external force F can be calculated based on the displacement Ax.
  • the shear modulus is a measure of the elastic shear stiffness of the material.
  • the force-sensing device 10 as described is configured to measure the normal component of the external force F, relative the surface of the floating element 12. If the external force F is applied at an angle, then the tangential component will generally not give rise to a predictable displacement according to the principles described above. To ensure that tangential force components or lateral expansion due to temperature change do not interfere with accurate measurement of the normal force component, preferably the shear spring 16 is much stiffer laterally than it is in the shear force direction i.e. the direction in which the floating element 12 is displaced. For example, stiffness of the shear spring 16 may be at least five times higher in the lateral direction.
  • the shear spring 16 is preferably present at three or more spaced apart regions (preferably equally spaced) intermediate of the floating member 12 and the base 14. This could be independent sections of the shear spring 16, as shown, but it will be appreciated that a single section could be present at more than one spaced apart region.
  • Figures 4C and 4D illustrate how the shear spring 16 may also have vertically or concentrically spaced sections. It will be appreciated that various arrangements of sections may act together to provide an elastic response that can be characterised for purposes of force measurement, and thus the multiple sections can collectively be considered to constitute the shear spring 16. However, splitting the shear spring 16 into such sections may increase complexity and is thus generally less preferable than a simpler (e.g. unitary) arrangement.
  • Figure 4B also shows the pitch and roll axes of the floating element 12. If the external force F is applied off-centre to the floating element 12, the floating element 12 may tilt these axes (yaw can generally be neglected). Tilting in this manner occurs in tandem with non-uniform shear deformation of the shear spring 16, as some regions will deform more than others. If only one displacement sensor 20 is used to measure the displacement of the floating element 12, then an external force F will not be measured with as much accuracy because not all parts of the floating element 12 will be displaced equally due to its tilt.
  • more than one displacement sensor 20 is provided to better account for off-centre external force application.
  • Two displacement sensors 20 can assist in accounting for one axis of tilt, but preferably at least three displacement sensors 20 are arranged nonlinearly (e.g. located at corners of a notional triangle or other polygon). Because different values for displacement will be measured by the displacement sensors 20 if the floating member 12 is tilted, use of standard algorithms can determine the orientation of the floating member 12 and properly characterise its displacement. As well as correcting the external force measurement, this allows a point of application of the external force F (i.e. its cartesian coordinates in the plane of the floating element 12) on the floating element 12 to be determined based on the combination of displacement measurements.
  • the external force F i.e. its cartesian coordinates in the plane of the floating element 12
  • displacement sensors 20 may be suitable, a preferred example arrangement is shown in the previous figures in which three displacement sensors 20 are arranged in an equilateral triangle about a central axis. This is a particularly convenient arrangement to facilitate calculations as described above.
  • sensors may be suitable for the displacement sensors 20, and selection may be based on the size of the force-sensing device 10. Because it is generally desirable for the force-sensing device 10 to be as small as possible, preferably the sensors are MEMS sensors which in general have a small package size and are well-suited for precision measurement over small ranges.
  • the displacement sensors 20 are of a non-contact type in that they are not incorporated into the shear spring 16 itself and do not rely on contact to function e.g. via a direct measurement of shear strain.
  • suitable non-contact sensors include optical or laser sensors which may function based on transit time of light, as well as capacitive or inductive sensors which may function based on a change in capacitance or inductance as two elements move relative each other.
  • the displacement sensors 20 are each located on a sensor-mounting surface 18 mounted to or forming part of the base 14, as shown in the previous figures. This ensures that the displacement sensors 20 are fixed relative to the base 14, which is important for accurate measurement of displacement. It also ensures that the sensor positions relative to the base 14, and by extension the floating element 12, can be accurately known for the purpose of calculations. Accurate location may be facilitated by through-holes or similar features in the sensor-mounting surface 18.
  • the sensor-mounting surface 18 may be provided underneath the floating element 12 with a gap therebetween.
  • the displacement sensors 20 are mounted to face the floating element 12 and measure a displacement when the floating element 12 moves closer into the gap.
  • the gap is less than 10 mm high and more preferably less than 5 mm high, which helps to limit the size of the force-sensing device 10.
  • the gap may be 1 mm high. Design of gap height and selection of the displacement sensors 20 is interrelated, because the selected displacement sensors 20 must perform adequately over the potentially small range of the gap height.
  • the sensor-mounting surface 18 may be a circuit board with electrical connections to the displacement sensors 20. However, circuitry may alternatively be located elsewhere, and the displacement sensors 20 may be operatively connected via wires.
  • the force-sensing device 10 as described has various benefits over alternative arrangements.
  • the shear spring 16 provides a mechanical structure with a temperature response that is less significant than for a similarly sized axial spring arrangement. This is especially beneficial for a miniaturised force-sensing device 10.
  • the shear spring 16 can provide a waterproof seal between the floating element 12 and the base, which may be useful in protecting the displacement sensors 20 and any other electronics from moisture damage.
  • the use of at least three displacement sensors 20 corresponding to different respective parts of the floating element 12 allows for better accuracy and for the point of application of the external force F to be determined in addition to force magnitude. This has a variety of applications where precise force measurement is needed and the contact point may change - some specific applications will subsequently be described.
  • shaping the shear spring 16 into a serpentine path can provide various benefits including better distributing stress and strain, improving vibration absorption, improving thermal expansion accommodation, and improve bonding strength.
  • a force-sensing apparatus 30 that incorporates force-sensing devices 10 will now be described.
  • a force-sensing apparatus 30 may comprise a plurality of force-sensing devices 10.
  • the force-sensing devices 10 have their bases 14 connected together, and can each independently measure external force applied thereto. This effectively creates a compound force-sensing device having greater force measurement surface area than a single force-sensing device 10, and may also provide a geometry suitable for a particular sensing application.
  • the force-sensing apparatus 30 comprises a frame 32 which mounts the bases 14 of the force-sensing devices 10.
  • the frame 32 which determines the orientation of the force-sensing devices 10.
  • the bases 14 of the force-sensing devices 10 may be connectable directly, connectable by intermediate connectors, or be integrally formed with each other.
  • the plurality of force-sensing devices 10 each have a unique orientation, allowing them to each measure external forces from different directions.
  • the frame 32 may substantially have the shape of a polyhedron - with at least some (preferably all) of the faces 34 mounting a force-sensing device 10.
  • the shape of each face 34 substantially corresponds to that of the force-sensing device 10 that it mounts, to allow convenient mounting and efficient use of surface area.
  • a preferred polyhedron for the frame 32 is a deltahedron i.e. having faces 34 which are equilateral triangles.
  • a preferred example, as shown in the figures, is an icosahedron having twenty such faces 34. However, it will be appreciated that many other geometries are possible.
  • the frame comprises a plurality of faces 34 each having a recess 36 within which one of the force-sensing devices 10 is seated.
  • the flange 24 of each force-sensing device 10, if present, may sit just outside the recess 36.
  • the force-sensing apparatus 30 comprises electronics to facilitate independent and self-contained operation.
  • electronics could include a battery, a charging interface, a real-time clock module, a memory storage medium (e.g. a removable SD card), an electronic controller which interfaces with the force-sensing devices 10 and manages their displacement sensors 20, and/or wireless communication hardware to facilitate transmission of sensor data (e.g. using Wi-Fi, Bluetooth, or radio protocols) to an external device.
  • sensor data e.g. using Wi-Fi, Bluetooth, or radio protocols
  • the forcesensing apparatus 30 may be at least partially hard-wired to external electronics to replace some or all of these functions, e.g. by direct wired connections to the force-sensing devices 10.
  • the electronics of the force-sensing apparatus 30 may include secondary sensors. Such secondary sensors may be useful in combination with the measurements of the forcesensing devices 10, and may also be managed by the electronic controller. Some degree of sensor fusion may occur between data from the secondary sensors and from the forcesensing devices 10.
  • an inertial measurement unit may allow impact loads from falling or dropping to be more easily identified in the force-sensing data and more thoroughly characterised, because they would be accompanied by a corresponding acceleration reading.
  • Tracking rotation/orientation through gyroscope and magnetometer data may also be useful, for example to better characterise tumbling or jostling motion.
  • Temperature readings may be used to account for a pre-characterised temperature response of the displacement sensors 20 or the mechanics of the force-sensing devices 10, for example by applying a correction in embedded software or in post-processing on an external device. Temperature readings may also be useful for other purposes, for example battery management or general environmental monitoring.
  • the frame 32 is at least partially hollow such that it can accommodate the electronics as described above. It may provide compartments or mounts for certain components, and may incorporate an externally accessible connector port (e.g. according to a USB standard) for charging and/or data transfer.
  • an externally accessible connector port e.g. according to a USB standard
  • the force sensing arrangement 10 and more specifically its floating element 12 may be engageable with a contact element 38.
  • the purpose of the contact element 38 is to receive the external force to be measured and transfer it to the floating element 12.
  • the contact element 38 extends out from the floating element 12 in a normal direction, and comprises a contact surface 40 for receiving the external force.
  • the shape of the contact surface 40, and of the contact element 38 as a whole, can be adapted to suit particular applications.
  • the outline of the contact element 38 substantially corresponds to the shape of the force-sensing device 10.
  • the contact element 38 has a substantially triangular outline.
  • the contact surface 40 is convex, which may be useful in defining a compound, curved force measurement surface together with the contact surfaces 40 of other force-sensing devices 10, as will be subsequently described.
  • the contact surface 40 could alternatively have any other shape, for example flat or concave, as suits a particular application.
  • the contact element 38 engages with engagement features 22 of the floating element 12, which may be formed as cavities.
  • the contact element 38 may comprise pegs 42 which correspond to the cavities (e.g. being configured to press fit into the cavities).
  • Engagement of the contact element 38 to the floating element 12 may be releasable, which may facilitate modularity in that contact elements 38 can be exchanged to suit different applications.
  • the engagement may be intended as permanent, which may be facilitated using an adhesive (e.g. applied into the cavities before inserting the pegs 42).
  • the contact element 38 may be integral with the floating element 12 rather than engageable with it.
  • the contact element 38 may comprise a lip 44 which extends beyond the perimeter of the floating element 12 and sits above the base 14. This allows the contact element 38 to perform a force/displacement-limiting function, as the lip 44 will bear against the base 14 (for example against its flange 24) or the frame 32 when a sufficiently large external force is applied. This can prevent any further displacement of the floating element 12, and protect the shear spring 16 and/or the displacement sensors 20 from damage due to external forces above a certain threshold.
  • the mechanical design of the components taking into account the elastic properties of the shear spring 16) can be adjusted to set the upper limit of force/displacement at a desired value.
  • the force-sensing apparatus 30 may provide a force measurement surface defined by the contact surfaces 40 of a plurality of contact elements 38 associated with the force-sensing devices 10.
  • the shape of the force measurement surface is therefore determined by the shape of the contact surfaces 40, which may all be substantially identical or at least similar. Alternatively, some or all of the contact surfaces 40 may have unique geometry.
  • the plurality of force-sensing devices 10 are arranged in a tessellated manner so as to present a force measurement surface substantially without gaps. Minimising the size of gaps provides better force-sensing coverage, in that external forces cannot easily be applied in gaps where they will not be sensed.
  • the force measurement surface is substantially spherical. This can be facilitated by the shape of the frame 32 being that of a suitable polyhedron.
  • the contact surfaces 40 also have a convex shape such that they can collectively define the substantially spherical surface. However, one or more of the contact surfaces 40 may be at least partially concave, for example to mimic the pitted shape about the stem of a typical apple.
  • the force-sensing apparatus 30 may be sized and shaped to mimic a type of fruit, preferably an apple. This allows the force-sensing apparatus 30 to be passed through post-harvest processes alongside real fruit and collect force data which may be indicative of how, when, or where the fruit is experiencing mechanical damage.
  • a spherical shape as described above may be suitable to mimic fruit.
  • the force-sensing apparatus 30 preferably has a diameter of between 40-120 mm.
  • a video recording may be made of the force-sensing apparatus 30 travelling through the post-harvest process, for example using one or more external cameras set up to observe the process and track the force-sensing apparatus 30.
  • Time stamp matching of the sensor data stream and the video will allow for a visual analysis of the video to occur to help identify where in the process the apparatus 30 is subjected to forces that may be causing damage, what the magnitude and causes of the forces are, the frequency of the forces, the location of the forces on the apparatus 30, and the orientation of the forces relative the horizontal.
  • the force-sensing apparatus 30 is configured to simultaneously monitor all external forces F as detectable from any of its force-sensing devices 10 during operation.
  • the force-sensing devices 10 are in different orientations, this allows external forces impinging from a variety of directions to be characterised. This may include crushing forces, which are especially useful to measure in fruit-mimicking applications.
  • at least some processing of the sensor data is performed on-board the force-sensing apparatus 30, for example by its electronic controller. Said processing may include signal filtering, force calculations, temperature correction, or other sensor fusions. This is preferably performed by embedded software but may at least in part be performed by dedicated hardware electronics. However, some or all of the processing of sensor data may occur in an external device to which the data is transmitted.
  • more complex sensor fusions or other tasks may be preferable to carry out on an external device.
  • One such task may be synchronisation and playback of the sensor data stream with a corresponding video recording as described above.
  • an external device may display a 3D model of the force-sensing apparatus 30 and translate the sensor data stream (whether streamed in real-time or played back later) into graphical indications of external force (e.g. using a colour mapping) displayed on the corresponding location of the force-sensing apparatus 30.
  • the 3D model may also be animated to rotate and/or translate in space according to the corresponding sensor data.
  • Provision of a plurality of force-sensing devices 10 in a force-sensing apparatus 30 has several benefits over other types of force-sensing apparatus.
  • crushing/compressive forces can be properly characterised which would not be possible with acceleration-based force sensing. This is especially relevant to fruit mimicry applications.
  • the structure of the force-sensing devices 10 facilitates tessellation so as to provide a force measurement surface substantially without gaps, which is useful to ensure that all external forces of interest are captured.
  • each force-sensing device 10 is only able to come into contact with one apple meaning that that there is only one source of force being applied to one force-sensing device 10.
  • the force-sensing devices 10 can be mounted such that they inherently waterproof an internal space of the force-sensing apparatus 30 (e.g. an at least partially hollow interior of frame 32). This is useful to shield internal electronics from moisture damage.
  • This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Force Measurement Appropriate To Specific Purposes (AREA)

Abstract

L'invention concerne un dispositif de détection de force comprenant un élément flottant, une base et un ressort de cisaillement intermédiaire les reliant. Une force externe appliquée à l'élément flottant est transférée à la base par l'intermédiaire du ressort de cisaillement. Un ou plusieurs capteurs de déplacement sans contact sont situés sous l'élément flottant sur une surface de montage de capteur, avec un espace entre l'élément flottant et les capteurs. Lorsque l'élément flottant est déplacé par une force externe, les capteurs mesurent le déplacement de l'élément flottant dans l'espace. Cela permet de mesurer une force appliquée sans contact direct, sur la base des propriétés élastiques du ressort de cisaillement. De multiples tels dispositifs de détection de force peuvent être combinés en un appareil de détection de force composite, par exemple pour simuler un fruit et mesurer les forces auxquelles il est soumis pendant un traitement post-récolte.
PCT/IB2024/061066 2023-11-08 2024-11-08 Dispositif et appareil de détection de force Pending WO2025099649A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AU2023903575A AU2023903575A0 (en) 2023-11-08 Force-sensing device and apparatus
AU2023903575 2023-11-08

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WO2025099649A1 true WO2025099649A1 (fr) 2025-05-15

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005047825A2 (fr) * 2003-11-04 2005-05-26 University Of Florida Detecteur d'ecoulement a element flottant micro-electromecanique
US20100326200A1 (en) * 2007-11-27 2010-12-30 Sheverev Valery A Shear Stress Measurement Apparatus
US8925384B2 (en) * 2012-05-29 2015-01-06 Freescale Semiconductor, Inc. MEMS sensor with stress isolation and method of fabrication
US20180156840A1 (en) * 2016-12-07 2018-06-07 Seiko Epson Corporation Physical quantity sensor, physical quantity sensor device, electronic apparatus, and vehicle
EP3594648A1 (fr) * 2017-03-08 2020-01-15 Nidec Copal Electronics Corporation Capteur de force

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2005047825A2 (fr) * 2003-11-04 2005-05-26 University Of Florida Detecteur d'ecoulement a element flottant micro-electromecanique
US20100326200A1 (en) * 2007-11-27 2010-12-30 Sheverev Valery A Shear Stress Measurement Apparatus
US8925384B2 (en) * 2012-05-29 2015-01-06 Freescale Semiconductor, Inc. MEMS sensor with stress isolation and method of fabrication
US20180156840A1 (en) * 2016-12-07 2018-06-07 Seiko Epson Corporation Physical quantity sensor, physical quantity sensor device, electronic apparatus, and vehicle
EP3594648A1 (fr) * 2017-03-08 2020-01-15 Nidec Copal Electronics Corporation Capteur de force

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
MICHAEL O'BRIEN, ROBERT B. FRIDLEY, JOHN R. GOSS, JAMES F. SCHUBERT: "Telemetry for Investigating Forces on Fruits During Handling", TRANSACTIONS OF THE ASAE, AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS, vol. 16, no. 2, 1 January 1973 (1973-01-01), pages 245 - 247, XP009563050, ISSN: 2151-0059, DOI: 10.13031/2013.37494 *

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