A novel electromagnetic end-effector with adaptive force-stiffness coordinated control for robotic grinding with variable workpiece stiffness

Abstract

This paper presents an adaptive force-stiffness coordinated control framework for custom-developed electromagnetic variable stiffness end-effector (EMVSE) used in robotic grinding with varying workpiece stiffness. The EMVSE generates actively controlled stiffness and force through designed voice coil motor and electromagnetic spring. The force-stiffness coordination control combines an optimized nonlinear PID force controller with bounded tracking error constraints and a self-stiffness controller based on real-time workpiece stiffness estimation, thereby achieving precise force control for grinding with variable workpiece stiffness. Experiments validate the effectiveness of the proposed method in improving the force control accuracy, material removal accuracy and surface quality of robotic grinding.