High precision tracking control using piezoelectric actuator network

Although piezoelectric actuators have been widely used in active control, the hysteresis nonlinearity and the non-minimum phase characteristic could potentially deteriorate the system performance, especially in high precision control applications under disturbance. In this study, a resistance/inductance circuit is connected to the piezoelectric actuator to form an actuator network. With the actuator dynamics, the system model can be directly cast into the state-space whereas the system nonlinearity appears as explicit functions of the state variables. We then develop an integral continuous sliding mode control scheme to tackle the hysteresis nonlinearity and the disturbance issues. Instead of inverse hysteresis cancellation which might not be reliable due to the measurement noise, a direct piezoelectric hysteresis compensation can be achieved using this control strategy. The newly developed control scheme combines the advantages of both integral control and continuous sliding mode control with cubic state feedback. Not only can the control action react efficiently and effectively for the non-minimum phase response, but also, a zero steady state tracking error is guaranteed. Detailed analysis and case studies demonstrate that this new methodology can lead to improved tracking control precision, enhanced control robustness, and smoother control action.