An inversion-free fuzzy predictive control for piezoelectric actuators

Piezoelectric actuators (PEAs) are treated as the core component in the nano-posistioning applications. The inherent hysteresis nonlinearity can dramatically degrade the tracking performance of PEAs. This paper presents an inversion-free fuzzy predictive controller of the parallel distributed structure. A Takagi-Sugeno (T-S) based fuzzy model of PEAs is developed first. With the aid of T-S based fuzzy model, explicit predictive control law can be obtained for each fuzzy rule. Then these predictive control laws are combined by fuzzy inference to generate the overall predictive controller. By the proposed method, the inverse hysteresis model of PEAs is no longer required. A notable feature of the proposed method is that the predictive control law can be obtained before the real-time control of PEAs. Therefore, the on-line computational burden is quite low, leading to a good tracking performance in the high frequency working conditions. Experiments are conducted on a commercial PEA to verify the proposed method. Experiment results show that the proposed method has a satisfactory tracking performance in both the low and high frequency conditions. Comparison results illustrate that the proposed method outperforms some existing approaches such as the inversion-based method and sliding mode control method.