ROBOT APPARATUS, ROBOT CONTROLLING METHOD, PROGRAM AND RECORDING MEDIUM

• US 20150165620A1
• Filed: 12/05/2014
• Published: 06/18/2015
• Est. Priority Date: 12/13/2013
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Osaka, Tsutomu
• Granted Patent: US 9,505,133 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B25J 13/088 with position, velocity or acceleration sensors
• CPC Class Codes: G05B 2219/40018 Ball in cup
• CPC Class Codes: Y10S 901/28 Joint
• CPC Class Codes: Y10S 901/30 End effector

Abstract

A joint driving unit driving a joint of a robot arm includes a motor, a speed reducer transmitting rotation of the motor in a variable speed, an input side encoder detecting a rotation angle of a rotation shaft of the motor, and an output side encoder detecting a rotation angle of an output shaft of the speed reducer. When positioning the end effector at a working start position at which predetermined work is started, operation of the robot is set to an output based control mode in which an angle of a joint is feedback controlled based on an angle detection value from the output side encoder. When the robot performs the predetermined work, the operation of the robot is changed to an input based control mode in which the angle of the joint is feedback controlled based on an angle detection value from the input side encoder.

Claims

1. A robot apparatus comprising:

a robot having a robot arm of multi-joint and an end effector attached to an end of the robot arm; and

a control unit configured to control an operation of the robot, wherein

the robot arm has a joint driving unit configured to drive the joint,

the joint driving unit has a rotating motor, a speed reducer transmitting a rotation of the rotating motor in a variable speed, an input angle detecting unit detecting a rotation angle of a rotation axis of the rotating motor or an input axis of the speed reducer, and an output angle detecting unit detecting a rotation angle of an output axis of the speed reducer, and

the control unit controls the operation of the robot, to set to an output based control mode such that an angle of the joint is feed-back controlled based on an angle detection value of the output angle detecting unit when the end effector is to be aligned with a working start position at which the robot starts a predetermined working, and to change to an input based control mode such that the angle of the joint is feed-back controlled based on an angle detection value of the input angle detecting unit when the operation of the robot is controlled to perform the predetermined working.

2. The robot apparatus according to claim 1, wherein

the working start position is set based on a distance from a work to the end effector, an accuracy of the work and an accuracy of the robot.

3. The robot apparatus according to claim 1, wherein

the control unit calculates a contortion angle of the joint based on the angle detection value of the input angle detecting unit and on the angle detection value of the output angle detecting unit when the robot performs the predetermined working, and to continue the predetermined working if the contortion angle does not exceed an acceptable value.

4. The robot apparatus according to claim 3, wherein

the control unit stops the predetermined working if the contortion angle exceeds the acceptable value.

5. The robot apparatus according to claim 3, wherein,

when the contortion angle exceeds the acceptable value, the control unit returns the end effector to the working start position, to operate the robot to perform the predetermined working.

6. The robot apparatus according to claim 3, further comprising

a warning unit configured to generate a warning to an user.

7. The robot apparatus according to claim 1, wherein

the end effector is a robot hand grasping a first work, and

the predetermined working is an inserting operation of inserting the first work into a second work.

8. The robot apparatus according to claim 7, wherein

the control unit determines the inserting operation as being completed, when the robot hand moves from the working start position in an inserting direction by a predetermined distance.

9. The robot apparatus according to claim 7, wherein

the control unit determines the inserting operation as being completed, when the robot hand moves from the working start position in an inserting direction and a contortion angle of the joint calculated based on the angle detection value of the input angle detecting unit and on the angle detection value of the output angle detecting unit reaches a predetermined value.

10. The robot apparatus according to claim 1, wherein

the end effector is a robot hand grasping a first work, and

the predetermined working is an extracting operation of extracting the first work from a second work.

11. The robot apparatus according to claim 10, wherein

the control unit determines the extracting operation as being completed, when the robot hand moves from the working start position in an extracting direction by a predetermined distance.

12. The robot apparatus according to claim 1, wherein

the robot arm has a plurality of the joint driving units each corresponding to each of joints thereof,

control unit sets the output based control mode of each of the plurality of the joint driving units when the end effector is to be aligned with a working start position, and to select at least one of the plurality of the joint driving units thereby changing the selected joint driving unit to the input based control mode.

13. The robot apparatus according to claim 1, further comprising

a teaching unit configured to teach an operation of the robot according to an operation by an user, and

the control unit changes to the input based control mode when the robot performs the predetermined working according to the operation of the teaching unit, and uses a teaching data based on data of the angle detection value of the output angle detecting unit input angle detecting unit.

14. The robot apparatus according to claim 13, wherein

the control unit searches a teaching position to control make smaller the contortion angle of the joint.

15. A robot controlling method for controlling, through a controlling unit, an operation of a robot having a robot arm of multi-joint and an end effector attached to an end of the robot arm, wherein

the robot arm has a joint driving unit configured to drive the joint,

the joint driving unit has a rotating motor, a speed reducer transmitting a rotation of the rotating motor in a variable speed, an input angle detecting unit detecting a rotation angle o of a rotation axis of the rotating motor or an input axis of the speed reducer, and an output angle detecting unit detecting a rotation angle of an output axis of the speed reducer, wherein the method comprising:

output controlling the operation of the robot by setting to an output based control mode such that an angle of the joint is feed-back controlled based on an angle detection value of the output angle detecting unit when the end effector is to be aligned with a working start position at which the robot starts a predetermined working, and

input controlling the operation of the robot by changing to an input based control mode such that the angle of the joint is feed-back controlled based on an angle detection value of the input angle detecting unit when the operation of the robot is controlled to perform the predetermined working.

16. A program for operating a computer to execute the robot controlling method according to claim 15.

17. A non-transitory computer-readable recording medium storing the program according to claim 16.