ROBOT, ROBOT CONTROL APPARATUS, ROBOT CONTROL METHOD, AND ROBOT CONTROL PROGRAM

• US 20130151009A1
• Filed: 02/05/2013
• Published: 06/13/2013
• Est. Priority Date: 03/17/2011
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: OKAZAKI, Yasunao
• Granted Patent: US 8,725,295 B2
• Time in Patent Office: Days
• US Class Current: 700/260
• CPC Class Codes: B25J 13/085 Force or torque sensors B25J13/082, B25J13/084 take precedence
• 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 9/1633 compliant, force, torque control, e.g. combined with position control
• CPC Class Codes: G05B 2219/36429 Power assisted positioning
• CPC Class Codes: G05B 2219/39342 Adaptive impedance control
• CPC Class Codes: G05B 2219/39346 Workspace impedance control

Abstract

A robot includes a multi-joint robot arm, an external force acquiring unit arranged at the multi-joint robot arm to acquire an external force, and an impedance control unit that causes the multi-joint robot arm to operate as a virtual spring-mass-damper system based on the external force acquired by the external force acquiring unit. The impedance control unit has an impedance map storage unit that defines impedance parameters at each of points of the work region, and an impedance map variable unit that changes the distribution of the impedance parameters in the impedance map storage unit in accordance with the current arm end position or the current arm end velocity of the multi-joint robot arm.

Claims

1. A robot, comprising:

a multi-joint robot arm;

an external force acquiring unit that is arranged at the multi-joint robot arm to acquire an external force;

an impedance map storage unit that stores, as an impedance map, a reference distribution of impedance parameters, the reference distribution of the impedance parameters associating positions of an arm end of the multi-joint robot arm shifting in accordance with an operation of the multi-joint robot arm with the impedance parameters including inertia, damping, and stiffness at each of the positions;

an impedance map variable unit that changes, in accordance with information of a current position of the arm end of the multi-joint robot arm, the distribution of the impedance parameters at one of a pre-position and a post-position relative to the position of the arm end performing an operation of the multi-joint robot arm with reference to the reference distribution of the impedance parameters in the impedance map; and

an impedance control unit that exerts impedance control over the multi-joint robot arm based on the external force acquired by the external force acquiring unit and the distribution of the impedance parameters changed by the impedance map variable unit.

2. The robot according to claim 1, further comprising

a velocity calculation unit that obtains a velocity by differentiating information of the positions of the arm end of the multi-joint robot arm, wherein

the impedance map variable unit changes, in accordance with the information of the current position of the arm end of the multi-joint robot arm and the velocity acquired by the velocity calculation unit, the distribution of the impedance parameters at one of a pre-position and a post-position relative to the position of the arm end where the arm end performs the operation of the multi-joint robot arm with reference to the reference distribution of the impedance parameters in the impedance map.

3. The robot according to claim 1, wherein

the impedance map variable unit changes the damping of the impedance parameter at a position where the arm end of the multi-joint robot arm passes such that the damping becomes higher after the arm end of the multi-joint robot arm has passed the position than before.

4. The robot according to claim 3, wherein

the impedance map variable unit raises the damping at the position where the arm end of the multi-joint robot arm has passed after the arm end of the multi-joint robot arm has passed the position, and thereafter lowers the damping at the position than a raised damping value when the arm end of the multi-joint robot arm is away from the position by a certain distance.

5. The robot according to claim 1, wherein

the impedance map stored in the impedance map storage unit has a first region of a low damping for allowing the arm end of the multi-joint robot arm to be shifted, a second region of a higher damping than the damping of the first region for allowing the arm end of the multi-joint robot arm to be positioned, and a third region of a higher damping than the damping of the second region, the third region being arranged so as to surround the second region, and

the impedance map variable unit changes an area of the second region surrounded by the third region, after the arm end of the multi-joint robot arm has entered the second region, to be smaller than an area before entrance of the arm end to the second region.

6. The robot according to claim 5, wherein

the impedance map variable unit changes a damping value of the second region, after the arm end of the multi-joint robot arm has entered the second region, toward a damping value lower than a damping value before the entrance of the arm end to the second region.

7. The robot according to claim 1, wherein

the impedance map stored in the impedance map storage unit has a first region of a low damping for allowing the arm end of the multi-joint robot arm to be shifted, and a second region of a higher damping than the damping of the first region for allowing the arm end to be positioned, wherein a fourth region of a higher damping than the damping of the first region and being equal to or smaller than the damping of the second region is set, the fourth region being for allowing the arm end to be positioned between the second region and the first region, and

the impedance map variable unit changes the damping of the fourth region, after the arm end has entered the fourth region, to be higher than the damping of the second region.

8. The robot according to claim 7, further comprising

a velocity calculation unit that obtains a velocity by differentiating information of the positions of the arm end of the multi-joint robot arm, wherein

the impedance map variable unit sets a height of the damping of the fourth region, in accordance with the information of the current position of the arm end of the multi-joint robot arm, and a velocity at which the arm end of the multi-joint robot arm enters the fourth region, the velocity being the velocity acquired by the velocity calculation unit.

9. A robot control apparatus, comprising:

an impedance map storage unit that stores, as an impedance map, a reference distribution of impedance parameters, the reference distribution of the impedance parameters associating positions of an arm end of a multi-joint robot arm shifting in accordance with an operation of the multi-joint robot arm with the impedance parameters including inertia, damping, and stiffness at each of the positions;

an impedance map variable unit that changes, in accordance with information of a current position of the arm end of the multi-joint robot arm, a distribution of the impedance parameters at one of a pre-position and a post-position relative to the position of the arm end performing an operation of the multi-joint robot arm with reference to the reference distribution of the impedance parameters in the impedance map; and

an impedance control unit that exerts impedance control over the multi-joint robot arm based on an external force acquired by an external force acquiring unit arranged at the multi-joint robot arm and the distribution of impedance parameters changed by the impedance map variable unit.

10. The robot control method, comprising:

acquiring an external force by an external force acquiring unit arranged at a multi-joint robot arm;

storing in an impedance map storage unit, as an impedance map, a reference distribution of impedance parameters, the reference distribution of the impedance parameters associating positions of an arm end of the multi-joint robot arm shifting in accordance with an operation of the multi-joint robot arm with the impedance parameters including inertia, damping, and stiffness at each of the positions;

changing, by an impedance map variable unit and in accordance with information of a current position of the arm end of the multi-joint robot arm, a distribution of the impedance parameters at one of a pre-position and a post-position relative to the position performing an operation of the multi-joint robot arm with reference to the reference distribution of the impedance parameters in the impedance map; and

exerting impedance control, by an impedance control unit, over the multi-joint robot arm based on the external force acquired by the external force acquiring unit and the distribution of the impedance parameters changed by the impedance map variable unit.

11. A computer-readable recording medium including a robot control program for causing a computer to function as:

an impedance map storage unit that stores, as an impedance map, a reference distribution of impedance parameters, the reference distribution of the impedance parameters associating positions of an arm end of a multi-joint robot arm shifting in accordance with an operation of the multi-joint robot arm with the impedance parameters including inertia, damping, and stiffness at each of the positions;

an impedance map variable unit that changes, in accordance with information of a current position of the arm end of the multi-joint robot arm, a distribution of the impedance parameters at one of a pre-position and a post-position relative to the position of the arm end performing an operation of the multi-joint robot arm with reference to the reference distribution of the impedance parameters in the impedance map; and

an impedance control unit that exerts impedance control over the multi-joint robot arm based on an external force acquired by an external force acquiring unit arranged at the multi-joint robot arm and the distribution of the impedance parameters changed by the impedance map variable unit.