Force sensorless workspace impedance control considering resonant vibration of industrial robot

This paper proposes a new force sensorless impedance control scheme for industrial robot to deal with the industrial robot under impact with environment. With the novel motion control based on D-PD (derivative-PD) and feedforward inverse-dynamic torque compensation, the industrial robot is assured in performing task with accuracy and rapidity. Only stiff servo strategy, however, the robot tends to encounter with difficulties when robot collides with the environment. The proposed observer-based workspace impedance control scheme does well match with the D-PD position control, which uses both position and velocity references to implement the damping and stiffness characteristic of the impedance model. The flexible-joint modeled industrial robot with its robust resonant-suppression motion control and force sensorless impedance control is an adequate platform to implement on the ordinary industrial robot system. Finally, the experimental results of the workspace impedance control performed on the three-degree-of-freedom (3-DOF) robot manipulator confirm the effectiveness of the proposed control scheme.