High-Precision Tracking of Piezoelectric Actuator Using Dual-Loop Iterative Learning Control

Suffering from rate-dependent hysteretic nonlinearity, accurate positioning of nanopositioning stage driven by piezoelectric actuators(PEAs) is hard to achieve and effective controllers are urgently needed. In this paper, by assuming that the model of PEA takes a Hammerstein structure, a dual-loop iterative learning control (ILC) scheme is designed to deal with both input hysteresis and linear dynamics of system synchronously. The merit of this controller lies in that, accurate system models are not prerequisite so that the control process is greatly simplified. As a comparison, an extra experiment using single loop ILC is performed to manifest the efficacy of the proposed algorithm. Simulation results show that the dual-loop ILC scheme is superior to the single loop ILC scheme in terms of convergence speed and control accuracy.