Adaptive control for piezo-actuated micro/nano positioning system

Abstract

The micro/nano positioning system discussed in this paper includes a piezo electric actuator (PEA) and flexure-hinge-based positioning mechanism. Due to the existence of the hysteretic nonlinearity in the PEA and the friction in the system, the accurate positioning of the piezo-actuated positioning system calls applicable control schemes for practical applications. To this end, an implementable adaptive controller is developed in the paper, where a parameterized hysteresis model is employed to reduce the computational load. The formulated adaptive control law guarantees the global stability of the controlled positioning system, and the position error can be driven to approach to zero asymptotically. The advantage is that the real values of the parameters of the positioning system neither need to be identified nor measured; only the parameters in the formulation of the controller are estimated online, making online implementation feasible. Experimental results show the effectiveness of the proposed method.