Abstract: In order to resolve the problem of force-position-posture coupling in automatic polishing systems and improve the polishing quality of aspheric part surface, a new decoupling control method for NC polishing based on magnetorheological torque servo (MRT) is proposed. Theoretical and experimental studies on the principle and model of this method are carried out. After a deep investigation into the coupling mechanism, the model of force-position-posture coupling is established based on Preston equation and Hertz theory, the principle of force-position-posture decoupling based on the MRT is introduced, the control models of polishing force and rotational speed of aspheric parts are deduced, and a corresponding experimental system is developed. Experiments are carried out, and mirror-like aspheric part surface with a roughness of Ra0.030 μm as well as constant material removal rates are obtained. Research results show that the MRT-based decoupling method can effectively resolve the problem of force-position-posture coupling, and provides a new way to achieve NC polishing of aspheric parts with high quality and efficiency and low cost.

Key words: Aspheric part surface, Decoupling control, Force-position-posture coupling, Magnetorheological torque servo, Material removal rate, NC polishing