Robot system, robot controller, and method for withdrawing robot

A robot controller comprising:

• a processor configured to:
• move a robot in a forward direction such that a representative point of the robot moves along a motion track in the forward direction, the robot having a plurality of motion axes and a plurality of sensors configured to detect an external force acting on the robot, the plurality of sensors being provided at the plurality of motion axes, respectively;
• move the robot in a reverse direction such that the representative point moves along the motion track in the reverse direction opposite to the forward direction when the external force satisfies a first condition which includes a condition that the external force is larger than a first threshold force;
• and
• move the robot to reduce the external force when the external force satisfies a second condition which includes a condition that the external force is larger than a second threshold force even after the robot has been moved in the reverse direction, the robot being moved to reduce the external force by moving one motion axis among a plurality of motion axes corresponding to a sensor among a plurality of sensors that detected a largest external force, among a plurality of external forces detected by respective sensors of the plurality of sensors, in a direction in which the largest external force reduces.

A method for controlling a robot, comprising:

• moving a robot in a forward direction such that a representative point of the robot moves along a motion track in the forward direction, the robot having a plurality of motion axes and a plurality of sensors configured to detect an external force acting on the robot, the plurality of sensors being provided at the plurality of motion axes, respectively;
• moving the robot in a reverse direction such that the representative point moves along the motion track in the reverse direction opposite to the forward direction when the external force satisfies a first condition which includes a condition that the external force is larger than a first threshold force;
• and
• moving the robot to reduce the external force when the external force satisfies a second condition which includes a condition that the external force is larger than a second threshold force even after the robot has been moved in the reverse direction, the robot being moved to reduce the external force by moving one motion axis among the plurality of motion axes corresponding to a sensor among the plurality of sensors that detected a largest external force, among a plurality of external forces detected by respective sensors of the plurality of sensors, in a direction in which the largest external force reduces.