Robot, robot control apparatus, robot control method, and robot control program

1. A control apparatus for a robot having a multi-joint robot arm, the control apparatus comprising:

a manipulation force acquiring unit disposed on the multi-joint robot arm, that acquires a manipulation force from a person;

a resistance force acquiring unit disposed on the multi-joint robot arm, that acquires a resistance force generated by friction caused by contact between a gripped object and an external environment when a motion of raising the gripped object is conducted with one side of the gripped object with respect to the external environment as a rotation center while the contact between the gripped object gripped by the multi-joint robot arm and the external environment is maintained;

an impedance controller that performs impedance control on the multi-joint robot arm based on the manipulation force acquired by the manipulation force acquiring unit and a set impedance parameter; and

an assist force correcting unit that corrects a force component vertical to a horizontal component of the resistance force of an assist force generated by the impedance controller according to the resistance force acquired by the resistance force acquiring unit so that a friction force caused by the contact between the gripped object and the external environment does not exceed a maximum static friction force when the motion of raising the gripped object is conducted.

2. A control apparatus for a robot having a multi-joint robot arm, the control apparatus comprising:

a manipulation force acquiring unit disposed on the multi-joint robot arm, that acquires a manipulation force from a person;

a resistance force acquiring unit disposed on the multi-joint robot arm, that acquires a resistance force generated by friction caused by contact between a gripped object and an external environment when a normal force from the external environment is reduced and a motion of conveying the gripped object along a surface of the external environment is conducted so as to drag the gripped object in contact with the external environment while the contact between the gripped object gripped by the multi-joint robot arm and the external environment is maintained;

an impedance controller that performs impedance control on the multi-joint robot arm based on the manipulation force acquired by the manipulation force acquiring unit and a set impedance parameter; and

an assist force correcting unit that corrects a force component vertical to a horizontal component of the resistance force or a component parallel to a wall surface of an assist force generated by the impedance controller according to the resistance force acquired by the resistance force acquiring unit, so that the horizontal component of the resistance force or the component parallel to the wall surface becomes a desired resistance force vector when the motion of dragging the gripped object is conducted.

3. The control apparatus for a robot according to claim 1 , wherein

the assist force correcting unit comprises

a direction controller that determines whether the force component vertical to the resistance force of the assist force is corrected in an increase direction or in a decrease direction according to a direction of the resistance force, and

a calculator that determines a correcting amount of the force component vertical to the resistance force of the assist force in proportion to magnitude of the resistance force based on the direction determined by the direction controller.

4. The control apparatus for a robot according to claim 2 , wherein the assist force correcting unit increases the force component vertical to the resistance force of the assist force generated by the impedance controller in proportion to magnitude of the resistance force.

5. The control apparatus for a robot according to claim 2 , wherein the assist force correcting unit decreases the force component vertical to the resistance force of the assist force generated by the impedance controller in proportion to magnitude of the resistance force.

6. The control apparatus for a robot according to claim 1 , wherein the assist force correcting unit corrects a force from gravity compensation of the gripped object as the force component vertical to the resistance force of the assist force generated by the impedance controller.

7. The control apparatus for a robot according to claim 5 , wherein the assist force correcting unit corrects a force from force control for pressing the gripped object against the external environment as the force component vertical to the resistance force of the assist force generated by the impedance controller.

8. The control apparatus for a robot according to claim 1 , wherein the resistance force acquiring unit is a force sensor disposed between an arm tip portion of the multi-joint robot arm and the gripped object gripped by the multi-joint robot arm.

9. The control apparatus for a robot according to claim 1 , wherein the resistance force acquiring unit is an external force estimating unit that estimates a torque generated on a joint of the multi-joint robot arm as a torque estimation value to acquire a resistance force based on the torque estimation value and the manipulation force acquired by the manipulation force acquiring unit.

10. A robot comprising:

a multi-joint robot arm; and

the control apparatus according to claim 1 , for controlling the robot.

11. A control method for controlling a robot having a multi-joint robot arm, the control method comprising:

acquiring a manipulation force from a person by a manipulation force acquiring unit disposed on the multi-joint robot arm;

acquiring a resistance force generated by friction caused by contact between a gripped object and an external environment by a resistance force acquiring unit disposed on the multi-joint robot arm when a motion of raising the gripped object is conducted with one side of the gripped object with respect to the external environment as a rotation center while the contact between the gripped object gripped by the multi-joint robot arm and the external environment is maintained;

performing impedance control on the multi-joint robot arm by an impedance controller based on the manipulation force acquired by the manipulation force acquiring unit and a set impedance parameter; and

correcting, by an assist force correcting unit, a force component vertical to a horizontal component of the resistance force of an assist force generated by the impedance controller according to the resistance force acquired by the resistance force acquiring unit so that the friction force caused by the contact between the gripped object and the external environment does not exceed a maximum static friction force when the motion of raising the gripped object is conducted.

12. A non-transitory computer-readable recording medium including a control program for a robot having a multi-joint robot arm, the control program causing a computer to function as:

an impedance controller that performs impedance control on the multi-joint robot arm based on a manipulation force from a person which is acquired by a manipulation force acquiring unit disposed on the multi-joint robot arm and a set impedance parameter;

a resistance force acquiring unit disposed on the multi-joint robot arm, that acquires a resistance force generated by friction caused by contact between a gripped object and an external environment when a motion of raising the gripped object is conducted with one side of the gripped object with respect to the external environment as a rotation center while the contact between the gripped object gripped by the multi-joint robot arm and the external environment is maintained; and

an assist force correcting unit that corrects a force component vertical to a horizontal component of the resistance force of an assist force generated by the impedance controller according to the resistance force so that the friction force caused by the contact between the gripped object and the external environment does not exceed a maximum static friction force when the motion of raising the gripped object is conducted.