A novel hybrid control strategy for trajectory tracking of fast tool servo

By integrating the fractional order PID (FPID) with repetitive control (RC), a hybrid control strategy is proposed for fast tool servo (FTS) to improve the trajectory tracking performances. A differential evolution algorithm is used to determine the optimal parameters of FPID controller. The control performances of conventional PID (CPID) and FPID controllers are compared by numerical simulation based on the response time and tracking accuracy, the results verify that FPID controller is of more excellent control performance. In order to improve the tracking performance of FTS on periodical command signals, RC is further integrated into the FPID control system. The feasibility and availability of the proposed hybrid controller has been examined by tracking control of a sinusoidal command, the results show that the tracking error of the hybrid controller is 1/11.7 and 1/4.5 times of CPID and FPID, respectively, and it is suitable for the trajectory tracking control of FTS.