Robotic grinding of a blisk with two degrees of freedom contact force control

Abstract

This paper presents a novel two degrees of freedom (DOFs) contact force control method for robotic blisk grinding. The grinding tool is controlled to automatically adapt to the curvity change of the blisk blade and maintain a constant contact force as expected. A smart end effector is used as the actuating device for contact force control. The proposed force controller includes a gravity compensation module, a force prediction module, and a force-position controller. The direction and amplitude of the contact force are predicted with the force prediction module and are controlled with the force-position controller. The tool path of the robotic blisk grinding process is generated and optimized so that the contact points between the tool tip and the workpiece are evenly distributed along the grinding path. Both simulations and experiments are carried out to validate the effectiveness of the proposed method. The results show that the proposed method provides a good contact force control performance, with less than 1 N force fluctuation. The surface finish and roughness are significantly improved compared to the case without force control. The grinding efficiency is raised by about sixfold compared to the case with one DOF force control.