Robot controlling method, robot apparatus, program and recording medium

1. A controlling method of a robot in which a controlling unit performs control for causing an actuator of each joint of a multi joint robot to operate according to each joint instruction value, the robot controlling method comprising:

calculating, by the controlling unit, a joint error of each joint of the robot, for each of the joints;

calculating, by the controlling unit, an error component in a driving direction of the actuator of the joint, for each of the joints;

calculating, by the controlling unit, a residuals component excluding the error component in the driving direction of the actuator from the joint error of the joint, for each of the joints;

calculating, by the controlling unit, an error in position and orientation of an end point of the robot based on the residuals component of each of the joints by forward mechanism calculation;

calculating, by the controlling unit, a first correction quantity for correcting the joint instruction value using the error component in a driving direction of the actuator of the joint, for each of the joints;

calculating, by the controlling unit, a second correction quantity for correcting the joint instruction value by using the error in position and orientation of the end point of the robot, for each of the joints by inverse mechanism calculation; and

correcting, by the controlling unit, the joint instruction value by using the first correction quantity and the second correction quantity, for each of the joints.

2. The controlling method according to claim 1 , wherein:

the controlling unit includes a correcting mode of correcting the joint instruction value, a non-correcting mode of not correcting the joint instruction value, and a transition mode upon a switch from the non-correcting mode to the correcting mode, and

in the correcting, the controlling unit multiplies at least one of the first correction quantity and the second correction quantity by a factor that monotonically increases from 0 to 1 with time in the transition mode, 0 in the non-correcting mode, and 1 in the correcting mode.

3. The controlling method according to claim 1 , wherein:

the controlling unit includes a correcting mode of correcting the joint instruction value, a non-correcting mode of not correcting the joint instruction value, and a transition mode upon a switch from the non-correcting mode to the correcting mode, and

in the correcting, the controlling unit multiplies a total correction quantity that is a sum of the first correction quantity and the second correction quantity by a factor that monotonically increases from 0 to 1 with time in the transition mode, 0 in the non-correcting mode, and 1 in the correcting mode.

4. The controlling method according to claim 1 , wherein:

the controlling unit includes a correcting mode of correcting the joint instruction value, a non-correcting mode of not correcting the joint instruction value, and a transition mode upon a switch from the correcting mode to the non-correcting mode, and

in the correcting, the controlling unit multiplies at least one of the first correction quantity and the second correction quantity by a factor that monotonically decreases from 1 to 0 with time in the transition mode, 0 in the non-correcting mode, and 1 in the correcting mode.

5. The controlling method according to claim 1 , wherein:

the controlling unit includes a correcting mode of correcting the joint instruction value, a non-correcting mode of not correcting the joint instruction value, and a transition mode upon a switch from the correcting mode to the non-correcting mode, and

in the correcting, the controlling unit multiplies a total correction quantity that is a sum of the first correction quantity and the second correction quantity by a factor that monotonically decreases from 1 to 0 with time in the transition mode, 0 in the non-correcting mode, and 1 in the correcting mode.

6. The controlling method according to claim 1 , wherein, in the calculating the joint error of each joint, the controlling unit obtains a first joint error of each of the joints caused by deformation of each of the joints and a second joint error of each of the joints caused by a fabrication error of the robot.

7. The controlling method according to claim 6 , wherein:

parameters of the fabrication error are stored in a storage unit, and

in the calculating the error in position and orientation of each joint, the controlling unit reads the parameters of the fabrication error from the storage unit when the controlling unit obtains the second joint error.

8. The controlling method according to claim 7 , wherein, in the calculating the error in position and orientation of each joint, the controlling unit corrects the parameters of the fabrication error according to temperature of the robot.

9. The controlling method according to claim 6 , wherein:

a fitting member for fitting the end point of the robot is arranged in an operation area of the robot, and

the controlling unit corrects the second error based on an actual position and orientation relative to a target position and orientation of the end point of the robot when the end point of the robot is fitted to the fitting member.

10. A robot apparatus comprising:

a multi-joint robot; and

a controlling unit configured to control the multi-joint robot,

wherein:

the controlling unit performs a control for causing an actuator of each joint of the multi-joint robot to operate according to each joint instruction value,

the controlling unit calculates a joint error of each joint of the robot, for each of the joints,

the controlling unit calculates an error component in a driving direction of the actuator of the joint, for each of the joints,

the controlling unit calculates a residuals component excluding the error component in the driving direction of the actuator from the joint error of the joint, for each of the joints,

the controlling unit calculates an error in position and orientation of an end point of the robot based on the residuals component of each of the joints by forward mechanism calculation,

the controlling unit calculates a first correction quantity for correcting the joint instruction value by using the error component in a driving direction of the actuator of the joint, for each of the joints;

the controlling unit calculates a second correction quantity for correcting the joint instruction value by using an error in position and orientation of the end point of the robot, for each of the joints by inverse mechanism calculation, and

the controlling unit corrects the joint instruction value by using the first correction quantity and the second correction quantity, for each of the joints.

11. A non-transitory computer-readable recording medium storing a program for operating a computer to execute a robot controlling method in which a controlling unit performs control for causing an actuator of each joint of a multi-joint robot to operate according to each joint instruction value, the program comprising:

code for calculating, by the controlling unit, a joint error of each joint of the robot, for each of the joints;

code for calculating, by the controlling unit, an error component in a driving direction of the actuator of the joint, for each of the joints;

code for calculating, by the controlling unit, a residuals component excluding the error component in the driving direction of the actuator from the error of the joint, for each of the joints;

code for calculating, by the controlling unit, an error in position and orientation of an end point of the robot based on the residuals component of each of the joints by forward mechanism calculation;

code for calculating, by the controlling unit, a first correction quantity for correcting the joint instruction value by using the error component in a driving direction of the actuator of the joint, for each of the joints;

code for calculating, by the controlling unit, a second correction quantity for correcting the joint instruction value by using the error in position and orientation of the end point of the robot, for each of the joints by inverse mechanism calculation; and

code for correcting, by the controlling unit, the joint instruction value by using the first correction quantity and the second correction quantity, for each of the joints.