Precise positioning control of a micropositioning system with nonminimum-phase plant

Flexure-based micropositioning systems with large motion range are attractive for a variety of precision engineering applications. The major challenge lies in how to design a suitable control scheme to achieve a precise positioning. In this paper, we propose an enhanced model predictive control (EMPC) strategy for the control of a micropositioning system with nonminimum-phase plant. By making use of the popular proportional-integral-derivative (PID) control algorithm, the EMPC is capable of finding the optimal incremental control action by imposing an appropriate suppression on the control effort. The theoretical analysis and effectiveness of the EMPC is verified by experimental and simulation studies. Comparative studies show that the EMPC scheme produces a much quicker response with lower steady-state error than the conventional MPC method. The proposed control strategy is extendable to other micropositioning systems with either a minimum-phase or nonminimum-phase plant.