Application of novel force control strategies to enhance robotic abrasive belt grinding quality of aero-engine blades

Abstract

Robotic belt grinding has emerged as a finishing process in recent years for machining components with high surface finish and flexibility. The surface machining consistency, however, is difficult to be guaranteed in such a process. To overcome this problem, a method of hybrid force-position control combined with PI/PD control is proposed to be applied in robotic abrasive belt grinding of complex geometries. Voltage signals are firstly obtained and transformed to force information with signal conditioning methods. Secondly, zero drift and gravity compensation algorithms are presented to calibrate the F/T transducer which is installed on the robot end-effector. Next, a force control strategy combining hybrid force-position control with PI/PD control is introduced to be employed in robotic abrasive belt grinding operations where the force control law is applied to the Z direction of the tool frame and the positon control law is used in the X direction of the tool frame. Then, the accuracy of the F/T transducer and the robotic force control system is analyzed to ensure the stability and reliability of force control in the robotic grinding process. Finally, two typical cases on robotic belt grinding of a test workpiece and an aero-engine blade are conducted to validate the practicality and effectiveness of the force control technology proposed.