Admittance Control of Manipulators in Unknown Environment

The manipulator may contact with obstacles when working in an unknown environment. The manipulator using position control only is unable to get away from the obstacle after contact with obstacles. Moreover, the contact force between the manipulator and the obstacle and the output torque of the joint actuator will increase with the increase of position error, which may damage the manipulator. In order to solve this problem, this paper proposes a control method of manipulator based on admittance control in unknown environment. This method applies a virtual force in the direction of vertical with contact force, and adopts admittance control in the direction of contact force and vertical with contact force respectively. The simulation results show that, compared with the manipulator only using position control, this method can reduce the output torque of joint actuator as well as when the manipulator contact with the obstacle, but also can make the manipulator get out of the obstacles to arrive at the target position. Therefore, using this method, the manipulator can complete the task safely in unknown environment.