Predictive Control With Enhanced Robustness for Precision Positioning in Frictional Environment

Predictive control employs future and past information to maintain servo performance and stability in uncertain environment. Nevertheless, nonlinear friction and unknown disturbances still challenge application of predictive control to precision positioning in typical electromechanical transmission systems due to strict demands on accuracy and control performance. In this paper, a modified predictive control strategy is developed to overcome positioning and tracking difficulties for transmission mechanism with friction. Enhanced robustness with respect to unknown dynamics is achieved by incorporating a zero phase error tracking controller (ZPETC) and a time-delay disturbance estimation scheme. Time delay control is used to cancel disturbances and potential nonlinearities. ZPETC is included to improve the overall system bandwidth. Both realistic numerical simulations, which consider the effect of sampling, quantization, and friction, and practical experiments are performed to investigate the effectiveness of the proposed control method. Encouraging transient response and steady-state control performance were observed in the results of positioning control of a one-dimensional transmission mechanism.