Compliance Control and External Force Estimation of 6-DOF Industrial Robots

Thanks to the advent of Industry 4.0, industrial robots have become more widely used, particularly for complex tasks such as human-robot cooperation. One such human-robot cooperation application is to teach a robot to execute a certain task by simply using the operator's hand to drag the end-effector of the robot to move along a desired path or move to a desired goal position. It is a more intuitive and convenient solution compared with traditional teach pendant. To make the robot compliant to the applied force of the human operator, compliance control schemes such as impedance control and admittance control are often used. The external force information is essential when implementing compliance control. In this paper, both force sensors and observer-based approaches such as the generalized momentum method are used to estimate external torque/force. Finally, the compliance control-based teach pendant developed in this paper is applied to a 6-axis industrial robot. Experimental results indicate that the proposed approach exhibits satisfactory performance.