In a system including a robot and a controller controlling the robot, the controller switches the robot from a first state to a second state in which orientation change in accordance with external force applied to the robot is more tolerated than the first state based on detection of contact of an object with the robot. The controller switches the robot from the second state to a third state in which the orientation change in accordance with the external force is more restricted than the second state after the orientation change in accordance with the external force applied to the robot is started and while the external force is being applied to the robot.

A control method of the composite robot includes acquiring multiple forces and multiple torques collected by the force sensor in the current motion when the robot arm is pulled to move; calculating multiple displacement value sets according to the multiple forces, the multiple torques, a preset desired force, a preset desired torque, and a preset model; calculating the optimal solution according to the multiple displacement value sets to obtain a first target displacement value corresponding to the robot arm and a second target displacement value corresponding to the motion mechanism; controlling the robot arm and the motion mechanism to move according to the first target displacement value and the second target displacement value; and repeating the operation of acquiring multiple forces and multiple torques collected by the force sensor in the current motion until the robot arm and the motion mechanism stop moving.

A device for acquiring a positional relationship between a robot coordinate system set in a robot and a working machine coordinate system set in a working machine installed outside the robot, includes a position data acquisition unit that acquires, when a finger part of the robot is placed in a predetermined position and posture with respect to the working machine, first position data indicating the position and posture of the finger part with respect to the robot coordinate system, and second position data indicating the position and the posture of the finger part with respect to the working machine coordinate system; and a positional relationship acquisition unit that acquires third position data indicating the positional relationship using the first position data and the second position data.