Gain scheduling control of ball screw feed drives based on linear parameter varying model

The time-varying and rigid-flexible coupling dynamic behaviors of ball screw feed drives (BSFD) are the main reasons that affect their tracking and positioning accuracy. The traditional PID control strategy cannot overcome the impacts resulted from these factors. A linear parameter varying (LPV) model based gain scheduling (GS) control method is proposed. Considering the time-varying and rigid-flexible coupling dynamic characteristics of a BSFD, its LPV model is established through identification experiments of the rigid-body transfer function, Stribeck friction, and elastic-body transfer function. Based on the LPV model, an output feedback GS control strategy is proposed, and a tuning method of the controller parameters is summarized. The comparison experiments between the GS and PID control strategies prove that the GS control strategy can ensure the consistency of tracking and positioning accuracy on the entire feed stroke of the BSFD. This work is of great significance for improving the machining accuracy reliability and accuracy retention of CNC machine tools.