ROBOT CONTROL SYSTEM, ROBOT SYSTEM, AND SENSOR INFORMATION PROCESSING APPARATUS

• US 20130116827A1
• Filed: 11/06/2012
• Published: 05/09/2013
• Est. Priority Date: 11/07/2011
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: INAZUMI, Mitsuhiro
• Granted Patent: US 8,958,914 B2
• Time in Patent Office: Days
• US Class Current: 700/260
• CPC Class Codes: B25J 13/08 by means of sensing devices, e.g. viewing or touching devices
• CPC Class Codes: B25J 9/16 Programme controls programme controls in general G05B19/00, e.g. numerical pogramme controls G05B19/18; recording or playback systems G05B19/42
• CPC Class Codes: B25J 9/1612 characterised by the hand, wrist, grip control
• 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 2219/39325 External force control, additional loop comparing forces corrects position
• CPC Class Codes: G05B 2219/39343 Force based impedance control
• CPC Class Codes: G05B 2219/39529 Force, torque sensor in wrist, end effector
• CPC Class Codes: G05B 2219/41166 Adaptive filter frequency as function of oscillation, rigidity, inertia load
• CPC Class Codes: Y10S 901/09 Closed loop, sensor feedback controls arm movement

Abstract

A robot control system includes a force control unit configured to output a correction value of a target track of a robot on the basis of sensor information acquired from a force sensor, a target-value output unit configured to apply correction processing based on the correction value to the target track to calculate a target value and output the calculated target value, and a robot control unit configured to perform feedback control of the robot on the basis of the target value. The force control unit includes a digital filter unit. The force control unit applies digital filter processing by the digital filter unit to the sensor information to calculate a solution of an ordinary differential equation in force control and outputs the correction value on the basis of the calculated solution.

Claims

1. A robot control system comprising:

a force control unit configured to output a correction value of a target track of a robot on the basis of sensor information acquired from a force sensor;

a target-value output unit configured to apply correction processing based on the correction value to the target track to calculate a target value and output the calculated target value; and

a robot control unit configured to perform feedback control of the robot on the basis of the target value, wherein

the force control unit includes a digital filter unit,

the force control unit applies digital filter processing by the digital filter unit to the sensor information to calculate a solution of an ordinary differential equation in force control and outputs the correction value on the basis of the calculated solution.

2. The robot control system according to claim 1, wherein the digital filter unit includes:

a digital-filter-coefficient output unit configured to output a digital filter coefficient on the basis of coefficient parameters of respective terms of the ordinary differential equation; and

a digital filter arithmetic unit configured to perform the digital filter processing on the basis of the digital filter coefficient and the sensor information.

3. The robot control system according to claim 2, wherein

the digital-filter-coefficient output unit includes:

a digital-filter-coefficient converting unit configured to perform processing for converting the coefficient parameters into the digital filter coefficient; and

a digital-filter-coefficient storing unit configured to store the digital filter coefficient converted by the digital-filter-coefficient converting unit, and

the digital-filter-coefficient output unit outputs the digital filter coefficient stored in the digital-filter-coefficient storing unit.

4. The robot control system according to claim 2, wherein

the digital-filter unit includes a digital-filter-stability-degree determining unit configured to determine a stability degree of operation of a digital filter used for the digital filter processing, and

the digital-filter-coefficient output unit outputs the digital filter coefficient when the digital-filter-stability-degree determining unit determines that the operation of the digital filter is stable.

5. The robot control system according to claim 2, wherein, when the digital filter processing is performed at a driving frequency of any one of a first driving frequency or a second driving frequency higher than the first driving frequency,

the digital-filter-coefficient output unit outputs at least one of a first digital filter coefficient corresponding to the first driving frequency and a second digital filter coefficient corresponding to the second driving frequency, and

the digital filter arithmetic unit performs, according to the digital filter coefficient output from the digital-filter-coefficient output unit, at least one of the digital filter processing by the first driving frequency in which the first digital filter coefficient is used and the digital filter processing by the second driving frequency in which the second digital filter coefficient is used.

6. The robot control system according to claim 5, wherein

the digital filter unit includes a selection processing unit configured to select one of the first driving frequency and the second driving frequency on the basis of signal frequency band information of the sensor information, and

the digital filter unit performs the digital filter processing at the driving frequency selected by the selection processing unit and outputs the correction value.

7. The robot control system according to claim 6, wherein the selection processing unit selects the driving frequency using, as the signal frequency band information, low-frequency sensor information obtained by applying low-pass filter processing to the sensor information and high-frequency sensor information obtained by applying high-pass filter processing to the sensor information.

8. The robot control system according to claim 5, wherein, when the driving frequency of the digital filter processing is switched from the high second driving frequency to the low first driving frequency, the digital filter arithmetic unit performs, in a first period, the digital filter processing by the second driving frequency in which the second filter coefficient is used, performs, in a switching period following the first period, both of the digital filter processing by the first driving frequency in which the first filter coefficient is used and the digital filter processing by the second driving frequency in which the second filter coefficient is used, and performs, in a second period following the switching period, the digital filter processing by the first driving frequency in which the first filter coefficient is used.

9. The robot control system according to claim 5, wherein, when the driving frequency of the digital filter processing is switched from the low first driving frequency to the high second driving frequency, the digital filter arithmetic unit performs, on the basis of a first output value, which is an output value of the digital filter processing by the first driving frequency in which the first filter coefficient is used at switching timing, and a second output value, which is an output value of the digital filter processing by the first driving frequency in which the first filter coefficient is used at timing in the past earlier than the switching timing, interpolation processing for calculating an interpolation value at timing between the switching timing and the timing in the past and performs, on the basis of the interpolation value, the digital filter processing by the second driving frequency in which the second filter coefficient is used.

10. The robot control system according to claim 2, wherein

the digital filter unit includes a first digital filter arithmetic unit and a second digital filter arithmetic unit as the digital filter arithmetic unit,

the digital-filter-coefficient output unit outputs a first digital filter coefficient to the first digital filter arithmetic unit and outputs a second digital filter coefficient different from the first digital filter coefficient to the second digital filter arithmetic unit,

the first digital filter arithmetic unit performs the digital filter processing based on the first digital filter coefficient and the sensor information, and

the second digital filter arithmetic unit performs the digital filter processing based on the second digital filter coefficient and the sensor information.

11. The robot control system according to claim 10, wherein the digital filter unit includes a digital-filter-output selecting unit configured to select any one of a processing result in the first digital filter arithmetic unit and a processing result in the second digital filter arithmetic unit and outputs the processing result as the correction value.

12. The robot control system according to claim 10, wherein, when the digital filter processing is performed at a driving frequency of any one of a first driving frequency or a second driving frequency higher than the first driving frequency,

the digital-filter-coefficient output unit outputs a digital filter coefficient corresponding to the first driving frequency as the first digital filter coefficient and outputs a digital filter coefficient corresponding to the second driving frequency as the second digital filter coefficient,

the first digital filter arithmetic unit performs the digital filter processing at the first driving frequency on the basis of the first digital filter coefficient, and

the second digital filter arithmetic unit performs the digital filter processing at the second driving frequency on the basis of the second digital filter coefficient.

13. The robot control system according to claim 12, wherein

the force control unit includes a band limiting unit configured to apply band limiting processing for allowing a given frequency band to pass to the sensor information and output the sensor information subjected to the band limiting processing to the first digital filter arithmetic unit and the second digital filter arithmetic unit, and

the band limiting unit outputs, to the first digital filter arithmetic unit, the sensor information subjected to band limiting processing for allowing a first frequency band to pass and outputs, to the second digital filter arithmetic unit, the sensor information subjected to band limiting processing for allowing a second frequency band wider than the first frequency band to pass.

14. The robot control system according to claim 2, wherein

the digital-filter-coefficient output unit includes a coefficient selecting unit configured to select any one of a first digital filter coefficient and a second filter coefficient different from the first digital filter coefficient, and

the digital-filter-coefficient output unit outputs the digital filter coefficient selected by the coefficient selecting unit to the digital filter arithmetic unit.

15. The robot control system according to claim 14, wherein, when the digital filter processing is performed at a driving frequency of any one of a first driving frequency or a second driving frequency higher than the first driving frequency,

the coefficient selecting unit selects any one of the first digital filter coefficient corresponding to the first driving frequency and the second digital filter coefficient corresponding to the second driving frequency,

the digital-filter-coefficient output unit outputs the digital filter coefficient selected by the coefficient selecting unit to the digital filter arithmetic unit, and

the digital filter arithmetic unit performs, when the first digital filter coefficient is output from the digital-filter-coefficient output unit, the digital filter processing at the first driving frequency on the basis of the first digital filter coefficient and performs, when the second digital filter coefficient is output from the digital-filter-coefficient output unit, the digital filter processing at the second driving frequency on the basis of the second digital filter coefficient.

16. The robot control system according to claim 15, wherein

the force control unit includes a band limiting unit configured to apply band limiting processing for allowing a given frequency band to pass to the sensor information and output the sensor information subjected to the band limiting processing to the digital filter arithmetic unit, and

the band limiting unit outputs, when the digital filter processing by the first driving frequency is performed, to the digital filter arithmetic unit, the sensor information subjected to band limiting processing for allowing a first frequency band to pass and outputs, when the digital filter processing by the second driving frequency is performed, to the digital filter arithmetic unit, the sensor information subjected to band limiting processing for allowing a second frequency band wider than the first frequency band to pass.

17. The robot control system according to claim 1, wherein the ordinary differential equation is an equation of motion including an imaginary mass term, an imaginary viscosity term, and an imaginary elasticity term as coefficient parameters.

18. The robot control system according to claim 1, wherein the target-value output unit includes:

a track generating unit configured to output target position information of the robot; and

an inverse kinematics processing unit configured to perform inverse kinematics processing on the basis of the target position information from the track generating unit and output joint angle information of the robot.

19. A robot system comprising:

the robot control system according to claim 1; and

a robot.

20. A sensor information processing apparatus comprising:

a sensor-information acquiring unit configured to acquire sensor information from a sensor; and

a sensor-information processing unit configured to apply processing to the acquired sensor information, wherein

the sensor-information processing unit includes a digital filter unit, and

the sensor-information processing unit applies digital filter processing by the digital filter unit to the sensor information to calculate a solution of an ordinary differential equation in the sensor information processing and outputs the solution as an output value of the sensor information processing.