Enhancing Robot End-Effector Trajectory Tracking Using Virtual Force-Tracking Impedance Control

This article presents an extended Cartesian space robot control framework that features a virtual force tracking impedance control to enhance the end-effector trajectory tracking performance. Initially, the concept of a virtual surface is introduced, which is assumed to be at some constant distance from the desired end-effector trajectory. This virtual surface generates a virtual contact force when interacting with the torque-controlled robot end-effector. The interaction is then manipulated using an impedance control model to track a constant desired force. If the robot end-effector deviates from the desired trajectory, the constant force-tracking impedance control generates a compliance trajectory that regulates the end-effector movements, constraining it to the desired trajectory. For robust force tracking, impedance parameters are optimally tuned using a closed-loop dynamic model incorporating both robot and impedance dynamics. Additionally, super twisting sliding mode control (STSMC) is integrated to overcome uncertainties and the impact of robot dynamics on force-tracking performance. Experimental validation confirms the theoretical claims of the proposed approach. It demonstrates that force-tracking impedance control improves the end-effector trajectory tracking by quickly reacting to the dynamic trajectories compared to position control only and effectively maintains it on the desired trajectories. This article introduces an extended Cartesian space robot control framework using virtual force-tracking impedance control to improve end-effector trajectory tracking. An assumed virtual surface near the desired trajectory generates a contact force, which is controlled by an impedance model to maintain a constant desired force. Optimal impedance parameters and super twisting sliding mode control enhance robustness and accuracy. Experiments validate the approach, showing superior trajectory tracking compared to position control alone.image (c) 2024 WILEY-VCH GmbH