Research on Friction Compensation Feedforward Control for Linear Motors Based on the Prandtl-Ishlinskii Model

The feeding axis driven by linear motors experiences nonlinear changes in friction resistance during the feeding process, making high-precision drive control difficult. By combining modeling and experiments, the Prandtl-Ishlinskii model is applied as the representative model for the linear motor servo system. The Prandtl-Ishlinskii model of the linear motor servo system is identified using output displacement as the system feedback signal. Based on this model, a friction compensation feedforward control scheme is proposed to compensate for nonlinear friction resistance. A comparative control study with and without feedforward control uses a self-built linear motor servo drive mechanism as the experimental platform. The results indicate that the proposed feedforward control scheme significantly improves the position-tracking accuracy of the linear motor servo system, reducing the relative error from 6.8% to 1.6% while tracking a sine curve.