# US 9,731,418 B2 · Methods and apparatus for closed loop force control in a linear actuator > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,731,418 B2 - Document ID: US9731418B2 - Status: Granted - Kind: B2 - Application number: 14/876,716 - Filed: 2015-10-06 - Published: 2016-06-30 - Granted: 2017-08-15 - Earliest claimed: 2014-10-06 - Assignees: Systems Machine Automation Components Corporation - Applicants: Systems, Machines, Automation Components Corporation - Inventors: Edward A. Neff; Toan M. Vu - Web page: https://patentgrep.com/patent/US9731418B2 ## CPC - B25J 9/1633: {compliant, force, torque control, e.g. combined with position control} - G05B 19/401: characterised by control arrangements for measuring, e.g. calibration and initialisation, measuring workpiece for machining purposes (G05B19/19 takes precedence) - G05B 2219/37021: Robot controls position of touch probe - G05B 2219/37207: Verify, probe, workpiece - G05B 2219/37411: Measure contact from force and velocity detection - G05B 2219/40599: Force, torque sensor integrated in joint - G05B 2219/45061: Measuring robot - G05B 2219/50109: Soft approach, engage, retract, escape, withdraw path for tool to workpiece - Y10S 901/09: Closed loop, sensor feedback controls arm movement - B25J: MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES ({manipulators specially adapted for use in surgery A61B34/70; manipulators used in cleaning hollow articles B08B9/04}; manipulators associated with rolling mills B21B39/20; manipulators associated with forging machines B21J13/10; {manipulators associated with picking-up and placing mechanisms B23P19/007}; means for holding wheels or parts thereof B60B30/00; {vehicles with ground-engaging propulsion means, e.g. walking members B62D57/02, B62D57/032; devices for picking-up and depositing articles or materials between conveyors B65G47/90, B65G47/91; manipulators with gripping or holding means for transferring packages B65H67/065}; cranes B66C; {manipulators used in the protection or supervision of pipe-line installations F17D5/00; walking equipment adapted for nuclear steam-generators F22B37/006}; manipulators specially adapted for, or associated with, nuclear reactors G21C; {apparatus used for handling wafers during manufacture or treatment of semiconductor H10P72/50}) - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A system and 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. ## Claims ### Claim 1 A method for using a probe assembly to apply force to a target surface, the method comprising: moving the probe assembly into an approach position, the approach position being a predetermined distance from the target surface; moving the probe assembly from the approach position to the target surface pursuant to a soft landing procedure, the soft landing procedure including determining that the probe assembly has moved into soft contact with the target surface wherein the probe assembly exerts an initial contact force on the target surface as a result of execution of the soft landing procedure; 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 a desired force different from the initial contact force wherein the applying includes applying an initial portion of the desired force to the target surface by operating the probe assembly in an open loop force control mode and incrementally applying a remaining portion of the desired force to the target surface by operating the probe assembly in a closed loop force mode of operation; and monitoring the applied force based upon an output of a load cell responsive to a force exerted by the probe assembly wherein the closed loop force mode of operation utilizes the output of the load cell. ### Claim 2 (depends on 1) The method of claim 1 wherein the initial portion of the desired force is at least 99% of the desired force. ### Claim 3 (depends on 2) The method of claim 2 wherein the probe assembly is moved in fixed steps during the closed loop force mode of operation. ### Claim 4 (depends on 1) The method of claim 1 wherein a least squares regression analysis is used in controlling movement of the probe assembly in fixed steps during the closed loop force mode of operation. ### Claim 5 (depends on 4) The method of claim 4 wherein the closed loop force mode of operation utilizes the output of the load cell. ### Claim 6 An apparatus, comprising: an actuator including a probe moveable in at least one dimension; a load cell operative to measure a force exerted by the probe on a contact surface and to provide an output signal based upon the force; and a controller configured to provide control signals to the actuator based upon a set of input parameters and the output signal wherein: pursuant to a soft landing procedure, first ones of the control signals cause the probe to move from an approach position to the contact surface, the soft landing procedure including determining that the probe has moved into soft contact with the contact surface wherein the probe exerts an initial contact force on the contact surface as a result of execution of the soft landing procedure, and during operation in an open loop force control mode subsequent to establishment of the soft contact between the probe assembly and the target surface, second ones of the control signals cause the probe to apply an initial portion of a desired force different from the initial contact force to the contact surface, and during operation in a closed loop force mode of operation, third ones of the control signals cause the probe to incrementally apply a remaining portion of the desired force to the target surface wherein the closed loop force mode of operation utilizes the output of the load cell. ### Claim 7 (depends on 6) The apparatus of claim 6 wherein the load cell is integrated with the probe. ### Claim 8 (depends on 6) The apparatus of claim 6 wherein the controller includes a memory for storing a probe movement profile corresponding to an application. ### Claim 9 (depends on 6) The apparatus of claim 6 wherein the initial portion of the desired force is at least 99% of the desired force. ### Claim 10 (depends on 9) The apparatus of claim 9 wherein a least squares regression analysis is used in controlling movement of the probe in fixed steps during operation in the closed loop force mode of operation. ### Claim 11 (depends on 6) The apparatus of claim 6 further including a load cell amplifier for amplifying the output signal.