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WO2016057570A1 - Procédés et appareils de régulation de force en boucle fermée dans un actionneur linéaire - Google Patents

Procédés et appareils de régulation de force en boucle fermée dans un actionneur linéaire Download PDF

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Publication number
WO2016057570A1
WO2016057570A1 PCT/US2015/054314 US2015054314W WO2016057570A1 WO 2016057570 A1 WO2016057570 A1 WO 2016057570A1 US 2015054314 W US2015054314 W US 2015054314W WO 2016057570 A1 WO2016057570 A1 WO 2016057570A1
Authority
WO
WIPO (PCT)
Prior art keywords
force
probe assembly
target surface
actuator
controller
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/US2015/054314
Other languages
English (en)
Inventor
Edward A. Neff
Toan M. VU
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.)
SMC Corp
Systems Machines Automation Components Corp
Original Assignee
SMC Corp
Systems Machines Automation Components Corp
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 SMC Corp, Systems Machines Automation Components Corp filed Critical SMC Corp
Publication of WO2016057570A1 publication Critical patent/WO2016057570A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
    • B25J9/00—Programme-controlled manipulators
    • B25J9/16—Programme controls
    • B25J9/1628—Programme controls characterised by the control loop
    • B25J9/1633—Programme controls characterised by the control loop compliant, force, torque control, e.g. combined with position control
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/18—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form
    • G05B19/401—Numerical control [NC], i.e. automatically operating machines, in particular machine tools, e.g. in a manufacturing environment, so as to execute positioning, movement or co-ordinated operations by means of programme data in numerical form characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B2219/00—Program-control systems
    • G05B2219/30—Nc systems
    • G05B2219/37—Measurements
    • G05B2219/37021—Robot controls position of touch probe

Definitions

  • the present disclosure pertains generally to machines which are useful for assembling or manufacturing an end product. More particularly, the present disclosure pertains to methods for controlling the forces that move assembly machine parts during assembly or manufacture of the end product. The present disclosure is particularly, but not exclusively, useful for the manufacture of end products that incorporate delicate or fragile components that require soft contact forces during assembly of the end product.
  • Quality control is important in the manufacture of components in an assembly process. Often, components are manufactured with precise dimensions and have tight critical tolerance requirements. Machines such as actuators can be used to inspect, measure and determine if one or more critical dimensions of the component are within tolerance. For example, the probe assembly of a moving coil actuator may be used to precisely measure a dimension of interest. The measurement is then used to determine if the dimension is within a tolerance window.
  • Linear actuators are mechanical devices which are used to perform repetitive actions requiring linear motion.
  • linear actuators can be used in an assembly plant for placing caps on bottles, for automatically stamping or labeling mail, for glass cutting, for placing chips on circuits, for testing various buttons or touch areas on electronic devices, for automation, and for a wide variety of other purposes as well.
  • a machine can be used for the manufacture of an end product that incorporates a probe assembly that is to be moved, for example, into contact with a work surface (or a target surface) on the end product. Because the machine operates to move a first body (the probe assembly) into contact with a second body (the target surface of the end product), forces are generated against both bodies by this action.
  • Methods and apparatus are described herein that can implement a dual open loop and closed loop procedure to apply a desired force to a target surface. Such methods may involve rapidly moving the probe assembly an approach position located a safe distance from the target surface. The approach position will typically be selected to be as close as possible to the target surface without risking abrupt or forceful contact with the surface. Once the probe assembly has been positioned close to, but safely above, the target surface, a soft landing procedure may be employed to bring the probe assembly in soft contact with the target surface.
  • a desired force may be applied to the surface by the probe assembly in accordance with one of at least two different procedures.
  • open loop force control is employed such that a relatively high percentage of the desired force is initially applied to the target surface.
  • a closed loop force control mode of operation may then be employed to increase the applied force to the desired level.
  • various linear and/or non-linear least squares regression analysis based techniques can be implemented to control the force applied to the probe assembly in fixed steps to very precisely achieve the desired force between the probe assembly and the target surface.
  • open loop force control is utilized to apply the desired force to the target surface.
  • the applied force may then be monitored by, for example, using a load cell or the like and adjusted to the extent necessary to maintain the applied force at the desired level.
  • the disclosure relates to a method for using a probe assembly to apply a desired force to a target surface.
  • the method includes moving the probe assembly into an approach position, the approach position being a predetermined distance from the target surface.
  • the probe assembly is then moved from the approach position to the target surface pursuant to a soft landing procedure.
  • the soft landing procedure includes determining that the probe assembly has moved into soft contact with the target surface.
  • the method further includes applying, subsequent to establishment of the soft contact between the probe assembly and the target surface, force to the probe assembly until an applied force on the target surface reaches the desired force.
  • the applied force may then be monitored based upon an output of a load cell responsive to a force exerted by the probe assembly.
  • the additional force may applied subsequent to the establishment of soft contact by applying an initial portion of the desired force to the target surface by operating the probe assembly in an open loop force control mode. A remaining portion of the desired force may then be applied to the target surface by operating the probe assembly in a closed loop force mode of operation which utilizes the output of the load cell.
  • the disclosure also pertains to an apparatus including an actuator having a probe moveable in at least one dimension.
  • a load cell is operative to measure a force exerted by the probe on a contact surface and to provide an output signal based upon the force.
  • a controller is configured to provide control signals to the actuator based upon a set of input parameters and the output signal.
  • FIG. 1 is a system block diagram of a programmable and automated, actuator- based component inspection system, according to an embodiment.
  • FIG. 2 is a hardware block diagram of an exemplary implementation an embodiment of a controller used in the system of FIG. 1.
  • FIG. 3 is a functional block diagram of a system including a closed loop force feedback arrangement used to effect soft contact of a probe assembly to a target, according to an embodiment.
  • FIG. 4 is a flowchart describing exemplary operation of the actuator apparatus described with reference to FIGS. 1-3.
  • FIG. 1 is a system block diagram of a programmable and automated, actuator- based component inspection system, according to an embodiment.
  • the system 100 includes an actuator 102, a controller 104, an input device 106 and a master controller 108. Also shown is a component 110 to be inspected, where the component is positioned by a handler 112.
  • the actuator 102 can be any actuator based device, such as a pneumatic, hydraulic or electrical actuator.
  • the actuator 102 is an electrical actuator, such as a moving coil actuator (also known as a voice coil actuator) or a moving magnet actuator. It is understood that although one actuator 102 is illustrated, the system 100 can be configured to include more than one actuator.
  • the actuator 102 includes a probe assembly 1 14 that is moveable in at least one axis.
  • the probe assembly 114 may be moved in an x, y and/or z axis relative to the body of the actuator 102.
  • the probe assembly 114 may be rotational ( ⁇ ) about one or more of the x, y and/or z axes.
  • the actuator 102 illustrated shows potentially four axes of actuation, an actuator may be provided that has only one axis of actuation.
  • the probe assembly 114 can be moved to contact different portions of a component 110.
  • the component 110 is moved into or held in an inspection orientation by the handler 1 12.
  • the handler 1 12 may be a robotic conveyor or gripper system controlled by the master controller 108 that locates the component 110 at a known reference location relative to the probe assembly 114.
  • the actuator 102 can include one or more encoders (not shown) that are capable of taking positional measurements about one or more axes. That is, in response to control signals from the controller 104, the actuator 102 sends measurements from its encoders to the controller 104 to indicate the precise positional location of the probe assembly about the relevant axes. In this way the probe assembly may be moved to an approach position relatively close to, but safely away from, a target surface of interest.
  • the probe assembly 1 14 is able to perform a "soft-land" operation where the probe assembly 1 14 is brought into contact with a surface of the component 1 10 so as not to damage the surface of the component 1 10 and also to establish an accurate contact location. Additional information about the soft- land operation is set forth in U.S. Patent No.
  • the soft-land procedure typically involves placing the probe assembly at an approach position.
  • This approach position can be arbitrarily established in accordance with the desires of the operator, but preferably, the approach position places the probe assembly much closer than about one millimeter away from the target surface.
  • the approach position will generally be dependent on the characteristics of the target surface; namely, the approach position can be made to be closer to smooth target surfaces relative to rougher surfaces without substantially increasing the risk of forceful, inadvertent contact.
  • the probe assembly is placed at the approach position for subsequent movement along a path from the approach position into soft contact with a predetermined point on the target surface.
  • each of these control modes depends on a measurable parameter that is characteristic of the movement of the probe assembly.
  • measurable parameters include i) the probe's travel position on the path toward the work surface (position control mode), ii) its velocity (velocity control mode), and iii) the acceleration/ deceleration of the probe assembly (torque control mode).
  • position control mode the probe's travel position on the path toward the work surface
  • velocity control mode the velocity control mode
  • torque control mode the acceleration/ deceleration of the probe assembly
  • none of the above mentioned measurable parameters are monitored and, instead, the probe assembly is allowed to merely advance into soft contact with target surface under the influence of the resultant force (basic mode).
  • the position control mode of operation, velocity control mode of operation and the torque control mode of operation are described in further detail in the '589 patent.
  • the actuator 102 can include one or more load cells (i.e., force sensors) that are capable of measuring force such as, for example, the force exerted by a probe assembly 1 14 on a target surface about a given axis.
  • load cells i.e., force sensors
  • activation of a load cell may determine when soft contact between the probe assembly 114 and the component 1 10 has been established.
  • the controller 104 may implement various open loop and/or closed loop modes of force control to cause the probe assembly to apply a desired force to the target surface.
  • the controller 104 will typically be responsive to an output signal (e.g., an electrical current) generated by the load cells.
  • the controller 104 can control the movements of the probe assembly 114.
  • the controller 104 can be a servo controller that can operate a moving coil actuator.
  • the master controller 108 controls the larger assembly and inspection system.
  • the master controller 108 can be a part of an inline assembly system that controls the flow or positioning of the component(s) 110 to be inspected by the actuator 102.
  • the master controller can send start/stop signals to the controller 104.
  • the controller 104 controls the inspection process of the actuator 102 and can output data, for example, in the form of measurements or pass/fail results of programmed tolerances. Accordingly, the controller 104 and/or the master controller 108 can determine if the inspected component is acceptable or should be discarded.
  • the controller 104 can be, for example, a Galil DMC31012 controller with built-in amplifier and a 16 bit analog output.
  • a switch test can be performed in which the probe assembly 1 14 is moved into position to depress a switch while monitoring the force required to depress the switch and/or to hold it in a depressed position. Such forces may be monitored to determine if the switch is within a specified tolerance window.
  • the controller 104 can generate control signals that operate the actuator 102.
  • the controller 104 can generate control signals and output such control signals to the actuator 102 to cause movement of the probe assembly 114 about one or more axes.
  • the controller 104 is programmed to control the actuator 102 depending on the application, i.e., depending on the component to be inspected.
  • the controller 104 includes software that is specifically configured to cause the desired actuator movement and measurement for the specific component to be inspected.
  • a computer (not shown) is coupled to the controller 104 to generate and transmit software (code representing a set of instructions to be executed) generated in a programming language to the controller for the specific application.
  • software code representing a set of instructions to be executed
  • Such software once running on the controller 104, will instruct actuator 102 to cause probe assembly 14 to perform movements and measurements for that specific application or component.
  • the programmed instruction or software can include instructions for the controller 104 to implement a force mode of operation and use a closed loop force feedback mechanism to guide and determine soft contact of the probe assembly 114 to the component 1 10 (i.e., target surface) as described in detail in relation to FIG. 3.
  • the actual soft contact force between the probe assembly 114 and the component 1 10 is monitored by a load cell that can be mounted directly onto the probe assembly 1 14 (or the actuator 102). Activation of the load cell may then be deemed to be determinative of when appropriate soft contact has occurred between the probe assembly 114 and the component 110.
  • a control system is provided to the controller 104 that includes generic programming instructions that are programmable by a user in a non-programming language to operate the actuator-based component inspection system in an automated fashion.
  • the controller 104 is provided with programming instructions (such as software generated by a programmer) stored in memory that can allow the user to finalize the programming of inspection controls to the specifics of the given application or component to be inspected, and without necessitating that the user have any knowledge of computer code programming. It is to be noted that these programming instructions are incomplete on their own such that without a motion profile for a specific component 1 10, the program instructions are unable to execute an inspection routine for that component 110.
  • a generic instruction program is developed and provided that includes a non- programming language user interface that allows the user to input and store all relevant parameters.
  • Such parameters may include, for example, probe movements, velocities, time delays, measurements and tolerance measurements that are specific to the application.
  • the code or instructions comprising the program can be the same for different applications, where the user can input parameters defining a motion profile that is used by the programmed instructions to operate the actuator 102 in automated use.
  • a motion profile can be referred to as a stored sequential set of probe movements and actions (e.g., to cause position measurements) and tolerance values associated with certain measurements which collectively define the operation of the probe assembly 114 and measurements taken during an inspection routine.
  • the program instructions can allow the user to program separate motion profiles for separate components that can be stored in the input device 106 or the controller 104.
  • motion profiles stored in the input device 106 can be transferred from the input device 106 to other controllers 104 operating other actuators 102.
  • the control system programming instructions are stored on and executed in part by both the input device 106 and the controller 104.
  • the input device 106 can be any device that can allow the user to input the desired actuator parameters such as, for example, a handheld device (e.g., a handheld pendant), a personal computer, a notebook computer, and/or the like.
  • the input device 106 can be coupled to the controller 104 via, for example, an RS-232, EIA-232, EIA-422 or EIA-485 connection. In other instances, however, the coupling of the input device 106 to the controller 104 can be done via any wired or wireless communication methods to communicate input data to the controller.
  • the input device 106 may be a separate device as illustrated in FIG.
  • controller 1 may be physically part of the controller 104 (as indicated by dashed control block 1 16).
  • the controller 104 may include an integrated user key entry means attached to the controller body.
  • the programming instructions stored on and executed by the input device 106 is different than the programming instructions stored on and executed by the controller 104 and collectively facilitates the user's ability to store a variety of motion profiles.
  • the input device 106 can include a display unit (not shown in FIG. 1) that can be, for example, a liquid crystal display (LCD) unit or a light emitting diode (LED) alphanumeric display unit that displays a graphical user interface (GUI) generated by the control system.
  • the GUI displayed on the display unit can allow a user to interact with the controller 104.
  • the GUI may include a set of displays having message areas, interactive fields, pop- ups, pull-down lists, notification areas, and buttons operated by user.
  • the GUI may include multiple levels of abstraction including groupings and boundaries.
  • GUI may be used in the singular or in the plural to describe one or more GUI's, and each of the displays of a particular GUI may provide users of the with an efficient and user- friendly communications and control tool for the controller 104.
  • the programming instructions or code (implemented as software and/or firmware) of the control system are configured to receive a variety of user input parameters via the input device 106 to establish and store an automated routine or motion profile for automated execution.
  • FIG. 2 is a hardware block diagram of an exemplary implementation of an embodiment of the controller 104 or, alternatively, of the control block 1 16.
  • the controller 104 includes a memory 202, a processor 204, an input module 206, an output module 208 and a bus 210.
  • the memory 202 can be, for example, any type of non- volatile memory device, a random access memory (RAM), a memory buffer, a hard drive, a database, an erasable programmable read-only memory (EPROM), an electrically erasable read-only memory (EEPROM), a read-only memory (ROM) and/or so forth.
  • RAM random access memory
  • EPROM erasable programmable read-only memory
  • EEPROM electrically erasable read-only memory
  • ROM read-only memory
  • the memory 202 can store instructions to cause the processor 204 to execute modules, processes and/or functions associated with the controller 104 and/or the control block 1 16. It is understood that although a single memory 202 is illustrated, the memory 202 may comprise one or more separate memory devices. Generically, the memory 202 may also be referred to as a computer readable medium. In a broad sense, the memory or computer readable medium refers to any type of medium that stores instructions executable by a processor, machine or computer. For example, the memory or computer readable medium may be any type of memory device. In several embodiments, the computer readable medium is a removable medium, such as a flash drive, floppy, hard, compact disc (CD), digital versatile disc (DVD), etc. Furthermore, the programming instructions stored on the memory 202 may be software and/or firmware.
  • the processor 204 can be a general purpose processor, a Field Programmable Gate Array (FPGA), an Application Specific Integrated Circuit (ASIC), a Digital Signal Processor (DSP), and/or the like.
  • the processor 204 can run and/or execute applications, modules, processes and/or functions associated with the controller 104 and/or the control block 116.
  • programming instructions can be provided that are stored on a memory 202 (or a computer readable medium) as a set of instructions to be executed on the processor 204 or other machine.
  • Such instructions allow a user to program or teach an automated actuator control system a motion profile for a specific application.
  • a motion profile can be a set of register values stored in the memory 202. Once the system is taught a motion profile, the programmed instructions use the stored motion profile to operate the actuator based automated inspection process. Thus, without the motion profile, the programmed instructions are not able to execute an inspection routine of a given component.
  • control system programming instructions are stored as code or a set of instructions in the memory 202. This code is executed or run by the processor 204 to implement the functionality of the code. For example, portions of the programmed instructions are retrieved from memory 202 by the processor 204 and executed using other information stored in memory 202 (e.g., as input by the user) and/or input information received from the input module 206. In use, one or more generated outputs (such a, for example, an actuator control signals, pass/fail signals, etc.) are output via the output 208 module. Referring to FIGS. 1-2, the input module 206 can receive inputs from an input device 106 (shown in FIG. 1), inputs from the master controller 108 (shown in FIG.
  • the output module 208 may send outputs to the actuator 102, to the master controller 108 and/or to the input device 106.
  • the output of the input device 106 allows data and instructions from the input device 106 to pass to the controller 104, while the input of the input device 106 receives data and instructions from the controller 104.
  • the programmed instructions stored in the memory of the input device can allow the user to enter and store one or more motion profiles corresponding to different components to be inspected by the actuator 102 in cooperation with the programmed instructions stored in the memory 202 of the controller 104 that control the actuator 102.
  • Such programmed instructions stored in the memory 202 of the controller 104 are based on user entered parameters at the input device 106 that are forwarded to the controller 104.
  • the memory of the input device is used to store multiple motion profiles.
  • the programmed instructions allow the stored motion profiles to be transferred from the input device 106 to additional controllers 104.
  • the programmed instructions stored in the memory of the input device allow for motion profiles that are generated elsewhere to be transferred into the input device 106.
  • the memory of the input device 106 can be used to store the "core” programming instructions that are to be used by a controller 104.
  • Such "core” programming instructions can include instructions for the controller 104 to implement a force mode of operation and use a close loop force feedback mechanism to guide and determine soft contact of the probe 1 14 to the component 1 10 (i.e., work surface) as described in detail in relation to FIGS. 3 and 4.
  • Such "core” programming instructions can also include instructions to implement various linear and/or non-linear least squares regression analysis based-methods for the probe 1 14 to reach the component 1 10 (i.e., the target) from either below the target level (bottom then upwards motion) or from above the target level (top then downwards motion).
  • a "core” programming instruction set (e.g., implemented as software and/or firmware) can refer to the programming instructions that would be used by a controller 104 to allow a user to program a motion profile as well as to operate the actuator 102, where the core programming instruction set is specific to the type of actuator 102 that is being controlled by the controller 104.
  • a first core programming instruction set is developed that is specific to a controller that controls an x-y actuator
  • a second core programming instruction set is developed that is specific to a controller that controls a linear and rotary (x and ⁇ ) actuator
  • a third core programming instruction set is developed that is specific to a controller that controls an x, y, z and rotary actuator.
  • the input device 106 can stores multiple core programming instruction sets that may be selectively transferred into a given controller 104, from, for example, a computer.
  • the stored motion profile(s) in the memory of the input device (not shown in FIGS.
  • the memory 202 as programmed by the user can include a set of registers in memory that each stores the commands and parameters needed for the particular inspection routine and component. Once the control system is taught a motion profile, the programmed instructions can use the stored motion profile to operate the actuator-based automated inspection process.
  • FIG. 3 is a functional block diagram of a system 300 including a closed loop force feedback arrangement used to guide and effect soft contact of a probe assembly to a target surface, and to then apply a desired force to the target surface, according to an embodiment.
  • the system 300 shown in FIG. 1 can be used to achieve soft contact between the probe assembly and the target surface with tight control of the contact force on the target surface (that can be part of a delicate or fragile end product).
  • a user may set the input parameters in the input device 306.
  • the input device 306 can be any device that can allow the user to input the desired actuator parameters such as, for example, probe movement profiles, velocities, time delays, measurements and tolerance measurements that are specific to the application.
  • the input device 306 can be, for example, a handheld device (e.g., a handheld pendant), a personal computer, a notebook computer, and/or the like.
  • the input device 306 can be coupled to the controller 304 via, for example, an RS-232, EIA-232, EIA-422 or EIA-485 connection.
  • the coupling of the input device 306 to the controller 304 can be done via any wired or wireless communication methods to communicate input data to the controller 304.
  • the input parameters can be included in a set of programming instructions that are, for example, programmable by the user to operate an actuator-based component inspection system in an automated fashion.
  • the input device 306 can include a display unit (not shown in FIGS. 1-3) that can be, for example, an LCD unit or a LED alpha-numeric display unit that displays a GUI generated by the control system that can allow a user to interact with the controller 304.
  • the GUI may include a set of displays having message areas, interactive fields, pop-ups, pull-down lists, notification areas, and buttons operated by user.
  • the GUI may include multiple levels of abstraction including groupings and boundaries.
  • the programming instructions or code (implemented as software and/or firmware) installed on the input device 306 can receive a variety of user input parameters. Such input parameters are typically associated with an automated routine or motion profile for automated execution. As described above, a motion profile can be stored sequential set of probe movements and actions (e.g., to cause position measurements) and tolerance values associated with certain measurements that as a whole define the operation of the probe and measurements taken during an inspection routine.
  • the set of input parameters entered by the user in the input device 306 can guide the functioning of the controller 304.
  • the controller 304 can generate control signals that control the operation of the actuator 302.
  • the controller 304 can be a servo controller that can generate control signals that operate a moving coil actuator 302.
  • the controller 304 in accordance with programmed instructions, typically in the form of software, the controller 304 generates controls signals and outputs those signals to the actuator 302 to cause movement of a probe assembly (or probe) about one or more axes.
  • the controller 304 can be, for example, a Galil DMC31012 controller with built-in amplifier and a 16 bit analog output.
  • the controller 304 can send signals to operate the actuator 302 in both open loop mode (e.g., torque mode) and/or closed loop mode (e.g., force mode or park mode).
  • open loop mode e.g., torque mode
  • closed loop mode e.g., force mode or park mode
  • the closed loop mode of operation can implement a close loop force feedback mechanism to achieve a target force (e.g., 5000 grams) on the target surface.
  • the actuator 302 is similar to the actuator 102 shown in FIG. 1 and can be a pneumatic, hydraulic or electrical actuator.
  • the actuator 302 is an electrical actuator, such as a moving coil actuator (also known as a voice coil actuator) or a moving magnet actuator that includes a linear encoder feedback mechanism.
  • the actuator 302 can include a probe assembly (not shown) that is moveable in at least one axis. For example, depending on the specific actuator used, the probe assembly may be moved in an x, y and/or z axis relative to the body of the actuator 302. Furthermore, the probe may be rotational ( ⁇ ) about one or more of the x, y and/or z axes.
  • the actuator 302 includes one or more encoders (not shown) that are capable of taking positional measurements about one or more axes. That is, in response to control signals from the controller 304, the actuator 302 sends measurements from its encoders to the controller 304 to indicate the precise positional location of the probe about the relevant axes.
  • the actuator 302 is operatively coupled to a load cell 312 (e.g., load cell 312 can be directly integrated on the shaft of the actuator 302).
  • the load cell 312 is a transducer (or force sensor) that can convert a force into an electrical signal.
  • load cells can be, for example, hydraulic load cells, pneumatic load cells, strain-gage load cells, and/or the like.
  • the load cell 312 measures the force exerted by the probe of the actuator 302 on a contact surface (i.e., target) about a given axis.
  • the electrical output signal of the load cell 312 is typically in the order of a few millivolts and typically necessitates amplification before it can be used.
  • the output of the load cell 312 can be scaled to calculate the force applied to the load cell 312 as the probe approaches the target.
  • the load cell 312 can be, for example, a Futek LSB200 load cell (i.e., force sensor) with a 0.01% accuracy that can operate in the 6000 g force range.
  • the load cell amplifier 314 is an instrumentation amplifier and amplifies the electrical output signal (e.g., a voltage or a current) of the load cell 312 and interfaces with the controller 304 to send the amplified electrical signal to the controller 304.
  • the load cell amplifier 314 can include an analog-to-digital converter to convert the analog output of the load cell amplifier 314 to a digital signal before sending the output signal to the controller 304.
  • the load cell amplifier 314 can be, for example, the Futek QIA121 analog amplifier with universal serial bus (USB) connectivity.
  • FIG. 4 is a flowchart describing exemplary operation 400 of the actuator apparatus described with reference to FIGS. 1-3.
  • the operation begins by moving the probe assembly of the actuator 302 to an approach position above or otherwise separated from the target surface (stage 410).
  • the probe assembly 114 is placed at an approach position of, for example, 250 microns relative to target surfaces which are rather smooth.
  • the approach position may be on the order of millimeters from the surface.
  • the probe assembly 1 14 of the actuator may be brought to the approach position using the position control mode of operation referenced above.
  • an optical encoder or any type feedback device that is well known in the pertinent art, can be used to monitor the position of the probe assembly 1 14 relative to the approach position.
  • a soft landing procedure is employed to bring the probe assembly in soft contact with the target surface (stage 420).
  • the soft landing procedure may use any one or more of the position, velocity and torque control modes described above to achieve soft contact between the probe assembly and the target surface.
  • the time rate of change of velocity of the probe i.e., the acceleration
  • the controller 104 is monitored using the encoder and timer circuitry in the controller 104.
  • Soft contact of the probe assembly 1 14 to the target surface of the component 110 results in an acceleration (deceleration or negative acceleration) of the probe assembly 1 14 and a determination of soft contact has occurs when the acceleration of the probe assembly 1 14 exceeds a predetermined threshold value. Alternatively, soft contact may be deemed to occur when the velocity of the probe assembly 114 is determined to be essentially equal to zero.
  • the probe exerts an initial contact force on the target surface of the component 1 10 of as a result of execution of the soft landing procedure, which may be 30-40 msec, in duration. [1061] Once such soft contact has occurred, the controller 304 may cause the desired force to be applied to the target surface of the component 1 10 in accordance with one of at least two different procedures.
  • open loop force control is employed such that a relatively high percentage of the desired force is initially applied to the target surface of the component 110 (stage 440).
  • electrical current is pumped to the actuator 302 (or probe assembly 1 14) to achieve a predetermined initial force on the load cell (e.g., 4950 gm in the case when the total desired force is 5000 gm).
  • a closed loop force mode of operation may then be employed to increase the applied force to the desired level (e.g., to 5000 gm) using the current or other feedback signal produced by the load cell 312 (stage 450).
  • the closed loop force mode of operation allows very precise control of forces in the range of 1 gram up to 10 kilogram-force (kgf) with 0.1 gm accuracy.
  • the kilogram-force is a gravitational metric unit of force and is equal to the magnitude of the force exerted by one kilogram of mass in a 9.80665 m/s 2 gravitational field (standard gravity).
  • the closed loop force mode step typically takes between 160-170 msec to complete and thus the total time taken to complete the entire operation of achieving 5000 gm force on the probe 1 14 (or load cell 312) and traveling 20 mm (open loop + closed loop) is approximately 200 msec.
  • the applied force Once the applied force has reached the desired level it may be monitored based upon the current of a feedback signal produced by the load cell 312 (stage 460).
  • second force control procedure 470 an open loop force control mode operation is employed after the soft landing procedure of stage 420 has been executed in order to apply the desired force to the target surface of the component 110 (stage 480).
  • the applied force may then be monitored based upon the current or feedback signal provided by the load cell 312 and adjusted to the extent necessary to maintain the applied force at the desired level (stage 490).
  • a module can be, for example, any assembly and/or set of operatively-coupled electrical components associated with performing a specific function(s), and can include, for example, a memory, a processor, electrical traces, optical connectors, software (that is stored in memory and/or executing in hardware) and/or the like.
  • a module can be, for example, any assembly and/or set of operatively-coupled electrical components associated with performing a specific function(s), and can include, for example, a memory, a processor, electrical traces, optical connectors, software (that is stored in memory and/or executing in hardware) and/or the like.
  • the singular forms "a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.
  • the term “an actuator” is intended to mean a single actuator or a combination of actuators.
  • Some embodiments described herein, such as for example, the noise reduction methods, relate to a computer storage product with a non-transitory computer-readable medium (also can be referred to as a non-transitory processor-readable medium) having instructions or computer code thereon for performing various computer-implemented operations.
  • the computer-readable medium or processor-readable medium
  • the media and computer code may be those designed and constructed for the specific purpose or purposes.
  • non- transitory computer-readable media include, but are not limited to: magnetic storage media such as hard disks, floppy disks, and magnetic tape; optical storage media such as Compact Disc/Digital Video Discs (CD/DVDs), Compact Disc-Read Only Memories (CD-ROMs), and holographic devices; magneto-optical storage media such as optical disks; carrier wave signal processing modules; and hardware devices that are specially configured to store and execute program code, such as Application-Specific Integrated Circuits (ASICs), Programmable Logic Devices (PLDs), Read-Only Memory (ROM) and Random-Access Memory (RAM) devices.
  • ASICs Application-Specific Integrated Circuits
  • PLDs Programmable Logic Devices
  • ROM Read-Only Memory
  • RAM Random-Access Memory
  • Examples of computer code include, but are not limited to, micro-code or microinstructions, machine instructions, such as produced by a compiler, code used to produce a web service, and files containing higher-level instructions that are executed by a computer using an interpreter.
  • embodiments may be implemented using imperative programming languages (e.g., C, Fortran, etc.), functional programming languages (Haskell, Erlang, etc.), logical programming languages (e.g., Prolog), object-oriented programming languages (e.g., Java, C++, etc.) or other suitable programming languages and/or development tools.
  • Additional examples of computer code include, but are not limited to, control signals, encrypted code, and compressed code.

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  • Engineering & Computer Science (AREA)
  • Human Computer Interaction (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Robotics (AREA)
  • Mechanical Engineering (AREA)
  • Manipulator (AREA)

Abstract

L'invention concerne un système et un procédé d'utilisation d'un ensemble sonde pour appliquer une force souhaitée sur une surface cible. Le procédé consiste à déplacer l'ensemble sonde jusqu'à une position d'approche, la position d'approche étant à une distance prédéterminée de la surface cible. L'ensemble sonde est ensuite déplacé de la position d'approche à la surface cible conformément à une procédure d'atterrissage souple. La procédure d'atterrissage souple comprend la détermination que l'ensemble sonde a été mis en contact souple avec la surface cible. Le procédé consiste en outre à appliquer, suite à l'établissement du contact souple entre l'ensemble sonde et la surface cible, une force à l'ensemble sonde jusqu'à ce qu'une force appliquée sur la surface cible atteigne la force souhaitée. La force appliquée peut ensuite être surveillée sur la base de la sortie d'un dynamomètre en réponse à une force exercée par l'ensemble sonde.
PCT/US2015/054314 2014-10-06 2015-10-06 Procédés et appareils de régulation de force en boucle fermée dans un actionneur linéaire Ceased WO2016057570A1 (fr)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4488242A (en) * 1980-12-22 1984-12-11 Fujitsu Limited Robot arm control method using open loop control in combination with closed loop control
US5594309A (en) * 1994-06-15 1997-01-14 Iowa State University Research Foundation, Inc. Robot control scheme
US20030009241A1 (en) * 2001-06-16 2003-01-09 Klaus Kruger Open-loop and closed-loop control method, and a control device for starting up and shutting down a process component of a technical process
EP1278109A1 (fr) * 2001-07-18 2003-01-22 Itt Manufacturing Enterprises, Inc. Méthode de régulation en boucle ouverte adaptée commutée en boucle fermée, pour un mouvement rapide d'un point à un autre dans un système de commande de mouvement périodique
US20050234565A1 (en) * 2004-04-01 2005-10-20 Systems, Machines, Automation Components, Corporation Programmable control system for automated actuator operation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4488242A (en) * 1980-12-22 1984-12-11 Fujitsu Limited Robot arm control method using open loop control in combination with closed loop control
US5594309A (en) * 1994-06-15 1997-01-14 Iowa State University Research Foundation, Inc. Robot control scheme
US20030009241A1 (en) * 2001-06-16 2003-01-09 Klaus Kruger Open-loop and closed-loop control method, and a control device for starting up and shutting down a process component of a technical process
EP1278109A1 (fr) * 2001-07-18 2003-01-22 Itt Manufacturing Enterprises, Inc. Méthode de régulation en boucle ouverte adaptée commutée en boucle fermée, pour un mouvement rapide d'un point à un autre dans un système de commande de mouvement périodique
US20050234565A1 (en) * 2004-04-01 2005-10-20 Systems, Machines, Automation Components, Corporation Programmable control system for automated actuator operation

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