Control system, program, and method of controlling mechanical equipment

• US 9,149,930 B2
• Filed: 07/10/2013
• Issued: 10/06/2015
• Est. Priority Date: 07/20/2012
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Inazumi, Mitsuhiro
• Primary Examiner(s): Edwards, Jerrah
• Assistant Examiner(s): WEBER, TAMARA L
• Application Number:
  US13/938,350
• Publication Number:
  US 20140025205A1
• Time in Patent Office: 818 Days
• Field of Search: 700/258
• US Class Current: 1/1
• CPC Class Codes: B25J 9/1633 compliant, force, torque control, e.g. combined with position control
• CPC Class Codes: B25J 9/1694 characterised by use of sensors other than normal servo-feedback from position, speed or acceleration sensors, perception control, multi-sensor controlled systems, sensor fusion
• CPC Class Codes: G05B 2219/39194 Compensation gravity
• CPC Class Codes: G05B 2219/39343 Force based impedance control
• CPC Class Codes: G05B 2219/40586 6-DOF force sensor
• CPC Class Codes: Y10S 901/46 Sensing device

Abstract

A control system includes a force sensor that has a mechanical mechanism (e.g., an end effector) and N (N is an integer equal to or more than two) triaxial force sensor units, acquires unit output values to which values resulting from the mechanical mechanism have been added from the respective triaxial force sensor units of the N triaxial force sensor units, and outputs force sense values based on the unit output values, a force sense value corrector that corrects the force sense values based on the force sense values output by the force sensor, and a controller that performs control of mechanical equipment (e.g., a robot) including the mechanical mechanism based on the force sense values corrected in the force sense value corrector.

Claims

1. A control system comprising:

a mechanical mechanism;

a force sensor that outputs force sense values; and

a controller that includes a force sense value corrector, the force sense value corrector corrects the force sense values outputted based on the force sense values from the force sensor and on position information of a mechanical equipment, wherein the controller performs control of the mechanical equipment including the mechanical mechanism based on the force sense values corrected by the force sense value corrector, wherein

the force sensor has N triaxial force sensor units, N is an integer equal to or more than two,

the force sensor acquires unit output values to which values resulting from the mechanical mechanism have been added from the respective triaxial force sensor units of the N triaxial force sensor units and outputs force sense values based on the unit output values,

the force sensor outputs information containing the unit output values from the respective triaxial force sensor units of the N triaxial force sensor units as the force sense values,

the force sense value corrector estimates a location of a center of mass of the mechanical mechanism based on the unit output values contained in the force sense values, and performs the correction processing based on the estimated location of the center of mass, and

the force sense value corrector estimates the location of the center of mass by obtaining a least squares solution of the location of the center of mass of the mechanical mechanism using a normalization equation.

2. The control system according to claim 1, wherein the force sense value corrector obtains N force vectors corresponding to forces respectively detected by the N triaxial force sensor units from the unit output values contained in the force sense values, estimates a mass of the mechanical mechanism based on a magnitude of a resultant vector of the obtained N force vectors, and performs the correction processing based on the estimated mass.

3. The control system according to claim 1, wherein the force sensor has three or more triaxial force sensor units.

4. The control system according to claim 1, wherein the force sensor has four or more triaxial force sensor units.

5. The control system according to claim 1, wherein:

the force sense value corrector performs processing of estimating the location of the center of mass of the mechanical mechanism according to first force sense values output from the force sensor based on the unit output values from the N triaxial force sensor units in a first position of the mechanical equipment,

the controller performs control of changing the position of the mechanical equipment to a second position different from the first position if a determination that the estimation of the location of the center of mass is impossible has been made by the force sense value corrector, and

after the controller controls the mechanical equipment to be in the second position, the force sense value corrector estimates the location of the center of mass of the mechanical mechanism according to second force sense values from the force sensor based on the unit output values from the N triaxial force sensor units, and performs the correction processing based on the estimated location of the center of mass.

6. The control system according to claim 1, wherein the force sense value corrector performs singular value decomposition on the normalization equation, and determines whether the estimation of the location of the center of mass is possible based on the number of singular values obtained by the singular value decomposition.

7. The control system according to claim 1, wherein:

the force sensor is a six-axial force sensor that acquires three values as the unit output values from each of the N triaxial force sensor units, and thereby, acquires 3×

N values, calculates translational forces Fx, Fy, Fz of X-axis, Y-axis, and Z-axis and moment Mx, My, Mz around the respective axes based on the acquired 3×

N values, and outputs information containing the calculated Fx, Fy, Fz and Mx, My, Mz as the force sense values.

8. The control system according to claim 1, wherein the force sense value corrector performs the correction processing based on a plurality of the force sense values obtained in a plurality of the positions of the mechanical equipment.

9. The control system according to claim 1, further comprising a position information acquirer that acquires position information of a variable part of the mechanical mechanism,

wherein the force sense value corrector estimates the location of the center of mass of the variable part and performs the correction processing based on the position information of the variable part.

10. The control system according to claim 1, wherein

the mechanical equipment is a robot,

the mechanical mechanism is an end effector of the robot,

the force sense value corrector acquires the force sense values from the force sensor provided in correspondence with the end effector of the robot, and performs correction processing of the acquired force sense values, and

the controller performs control of the robot and the end effector based on the force sense values after the correction processing.

11. A program causing a computer to function as:

a controller that includes a force sense value corrector, the force sense value corrector acquires force sense values from a force sensor provided in correspondence with a mechanical mechanism of mechanical equipment, wherein;

the force sense values includes information containing unit output values acquired by the force sensor,

the force sense value corrector estimates a location of a center of mass of the mechanical mechanism based on the unit output values contained in the force sense values by obtaining a least squares solution of the location of the center of mass of the mechanical mechanism using a normalization equation,

the force sense value corrector performs the correction processing based on the estimated location of the center of mass, and

the controller performs control of the mechanical equipment and the mechanical mechanism based on the force sense values after the correction processing.

12. A method of controlling mechanical equipment comprising:

acquiring force sense values from a force sensor provided in correspondence with a mechanical mechanism of the mechanical equipment, wherein the force sensor has N triaxial force sensor units, N is an integer equal to or more than two, the force sensor acquires unit output values to which values resulting from the mechanical mechanism have been added from the respective triaxial force sensor units of the N triaxial force sensor units and outputs force sense values based on the unit output values, the force sense values include information containing the unit output values output from the respective triaxial force sensor units of the N triaxial force sensor units;

estimating a location of a center of mass of the mechanical mechanism based on the unit output values of the force sense values, wherein the location of the center of mass is estimated by obtaining a least squares solution of the location of the center of mass of the mechanical mechanism using a normalization equation;

performing correction processing on the acquired force sense values based on the estimated location of the center of mass; and

performing control of the mechanical equipment and the mechanical mechanism based on the force sense values after the correction processing.