Robot controlling method, robot apparatus, program and recording medium

Patent metadata

Field	Value
Publication number	US-2016263747-A1
Application number	US-201615058904-A
Country	US
Kind code	A1
Filing date	Mar 2, 2016
Priority date	Mar 13, 2015
Publication date	Sep 15, 2016
Grant date	—

Abstract

A control apparatus makes a robot hand grip a work for measurement. The control apparatus controls the operation of a robot arm so that the robot arm keeps a force of striking the work for measurement against a reference constant, while making the end portion of the robot arm rotate around the end axis, in a state of making the outer periphery F 3 of the work for measurement, which is gripped by the robot hand, strike against the reference jig. The control apparatus acquires a detection result detected by an encoder of each of the joints when the end portion of the robot arm has been rotated. The control apparatus calculates a correction amount of trajectory data based on eccentricity of a central axis with respect to an end axis, by using the detection result of the encoder, and corrects the trajectory data, based on the correction amount.

First claim

What is claimed is:

1 . A robot controlling method in which a robot hand is attached to the end portion of a robot arm having a plurality of joints, each of the joints of the robot arm has a joint driving apparatus that has a motor and a joint angle detecting unit that detects a joint angle, and a control apparatus that controls an operation of the robot arm, based on trajectory data for performing the operation, comprising:
gripping in which the control apparatus makes the robot hand grip a symmetrically shaped member having such a shape as to be rotationally symmetric with respect to the central axis; operating in which the control apparatus controls the operation of the robot arm so that the robot arm keeps a force of striking the symmetrically shaped member against a reference member constant, while making the end portion of the robot arm rotate around the end axis, in a state of making the outer periphery of the symmetrically shaped member, which is gripped by the robot hand, strike against the reference member; acquiring in which the control apparatus acquires a detection result which has been detected by the joint angle detecting unit of each of the joints when the end portion of the robot arm is rotated in the operating; and correcting in which the control apparatus calculates a correction amount of the trajectory data based on eccentricity of the central axis with respect to the end axis, by using the detection result which the control apparatus has acquired in the acquiring, and corrects the trajectory data, based on the correction amount.

2 . The robot controlling method according to claim 1 , wherein in the correcting, the control apparatus calculates a position of the end portion of the robot arm from the detection result which has been detected by the joint angle detecting unit of each of the joints that the control apparatus has acquired in the acquiring, according to forward kinematics; determines information on the eccentricity of the central axis with respect to the end axis from the calculation result; and calculates the correction amount from the information on the eccentricity.

3 . The robot controlling method according to claim 1 , wherein
the control apparatus performs each of the operating and the acquiring in the case of making a first portion in the outer periphery of the symmetrically shaped member in a direction of the end axis strike against the reference member, and in the case of making a second portion in the outer periphery of the symmetrically shaped member in the direction of the end axis, which is different from the first portion, strike against the reference member; and in the correcting, the control apparatus calculates information on the eccentricity of the central axis with respect to the end axis, and information on a gradient of the central axis with respect to the end axis, by using the result which the control apparatus has acquired in the acquiring, and calculates the correction amount from the information on the eccentricity and the information on the gradient.

4 . The robot controlling method according to claim 3 , wherein
in the correcting, the control apparatus determines each of offset quantities of the central axis with respect to the end axis in the cases of making each of the first portion and the second portion strike against the reference member, from the detection result which the control apparatus has acquired in the acquiring in the case of making the first portion strike against the reference member, and the detection result which the control apparatus has acquired in the acquiring in the case of making the second portion strike against the reference member, on such a condition that the end portion of the robot arm is set at a same rotation angle; and determines the information on the gradient from the two offset quantities and distances between the first portion and the second portion, in the direction of the end axis.

5 . The robot controlling method according to claim 1 , wherein
the robot arm has a force sensor for detecting a force which is exerted on the robot hand arranged therein; and in the operating, the control apparatus acquires the detection result of the force which has been detected by the force sensor, as a force with which the symmetrically shaped member strikes against the reference member.

6 . The robot controlling method according to claim 1 , wherein
the joint driving apparatus further has a speed reducer which decelerated the rotation of the motor; the joint of the robot arm has a motor angle detecting unit which detects a rotation angle of the motor; and in the operating, the control apparatus determines the force with which the symmetrically shaped member strikes against the reference member by using the result of the detected angle by the motor angle detecting unit of each of the joints, and the result of the detected angle by the joint angle detecting unit.

7 . The robot controlling method according to claim 6 , wherein
in the operating, the control apparatus calculates a torque which is exerted on each of the joints, by using the angle detection result of the motor angle detecting unit of each of the joints and the angle detection result of the joint angle detecting unit; and determines the force with which the symmetrically shaped member strikes against the reference member, by using the calculation result of the torque of each of the joints.

8 . The robot controlling method according to claim 7 , wherein
in the operating, the control apparatus calculates the torque which is exerted on the joint from a difference between a result in which the angle detection result of the motor angle detecting unit has been converted into an angle of the joint at a previously set reduction ratio of the speed reducer, and the angle detection result of the joint angle detecting unit, and from previously set torsional stiffness of the speed reducer; and calculates the force with which the symmetrically shaped member strikes against the reference member, from the calculation result of the torques of each of the joints and previously set link parameters of the robot arm.

9 . A robot apparatus comprising:
a robot arm having a plurality of joints; a robot hand mounted on an end portion of the robot arm; a controlling apparatus configured to control an operation of the robot arm based on trajectory data for performing the operation, wherein each of the joints of the robot arm has a joint driving apparatus that has a motor and a joint angle detecting unit that detects a joint angle, and the controlling apparatus configured to execute a robot controlling method in which the robot hand is attached to the end portion of the robot arm having, comprising: gripping in which the control apparatus makes the robot hand grip a symmetrically shaped member having such a shape as to be rotationally symmetric with respect to the central axis; operating in which the control apparatus controls the operation of the robot arm so that the robot arm keeps a force of striking the symmetrically shaped member against a reference member constant, while making the end portion of the robot arm rotate around the end axis, in a state of making the outer periphery of the symmetrically shaped member, which is gripped by the robot hand, strike against the reference member; acquiring in which the control apparatus acquires a detection result which has been detected by the joint angle detecting unit of each of the joints when the end portion of the robot arm is rotated in the operating; and correcting in which the control apparatus calculates a correction amount of the trajectory data based on eccentricity of the central axis with respect to the end axis, by using the

Assignees

• Canon Kk

Inventors

• Yokoi Akiyoshi

Classifications

• B25J9/1633

  compliant, force, torque control, e.g. combined with position control · CPC title

• G05B2219/39325

  External force control, additional loop comparing forces corrects position · CPC title

• G05B2219/39529

  Force, torque sensor in wrist, end effector · CPC title

• G05B2219/39041

  Calibrate only for end position · CPC title

• G05B2219/39183

  Compliance compensation · CPC title