Nonlinear discrete prescribed performance control for micro-positioning of smart actuators

Most smart material based actuators (smart actuators) are known for their prominent characteristics of a high resolution of positioning, high bandwidth, and the ease of integration in miniaturized systems. However, their applications are restricted by the inherent hysteresis nonlinearity. This paper presents a new nonlinear discrete control design to improve hysteresis compensation in the smart actuators particularly in the piezoelectric based actuators. The control development takes the prescribed performance control framework as the basis and fuses it into a new modified Bouc-Wen (MBW) model. Through the theoretical analysis, it is shown that the designed control law guarantees the stability of the closed-loop system. Finally, the efficacy of the control framework is verified via a real case application where a linear piezoelectric actuated positioning system (PEA stage) is used as the testbed. The experimental results confirm that the formulated control scheme has the capacity for improving the output-tracking performance in the PEA stage.