Precise Motion Control Of A Piezoelectric Actuator

With the developments of high precision industries, the requirement of a micro/nano positioning system is more and more compulsory. Piezoelectric actuators(PZTs) have been widely adopted because of its nanometer positioning resolution, high stiffness, fast response, etc. The nonlinear hysteresis effect of piezo-stages limits the motion precision. To overcome this problem, this thesis explores positioning and trajectory tracking approaches for piezoelectric actuators. The main content of this thesis are as follows:First, a PID sliding mode control approach based on part of the system model parameters is proposed. To alleviate the chattering phenomenon, a saturation function is used to replace the signum function and thus a continuous PID controller is formulated.Second, considering the fact that the exact model parameters of the system is not easy to obtain, a model-free PID sliding mode control approach is developed.Finally, to address the weakness of larger control gains of the model-free PID sliding mode control, the adaptive technique is introduced to give an estimate of the unknown model paramaters and an adaptive PID sliding mode control method is proposed.Lyapunov method is used to prove the global asymptotic stability of the closed-loop system. Simulations are carried out to demonstrate the effectiveness and improved performance of the proposed approaches.