A Normal Tracking Method for Workpieces with Free-Form Surface in Robotic Polishing

Polishing operations often require constant normal contact forces, making robotic systems difficult to apply in polishing operations with offline programming methods that the geometric information of workpieces is lacking. This paper proposes a new method to achieve normal contact control between a polishing tool and workpieces without priori geometric information and designs a robot end-effector applicable to this method. The method employs three laser distance sensors and a linear encoder to form a measurement system. The theoretical analysis and simulation verification of the proposed method shows that the proposed method can obtain a higher normal tracking accuracy with an average error of 0. 37^∘. An experimental platform built based on the proposed method also achieves good normal tracking in the actual polishing process. Both simulation and experimental results show that the proposed method provides a viable robotic polishing method when workpieces have no precise geometric models.