Creep and Hysteresis Compensation with Feedforward/Feedback Controller for an Ultra-Precise Nanopositioning Stage

Compensation of hysteresis and creep in the micro/nanopositioning stage is an essential task to achieve an ultra-precise reference tracking with desired accuracy, performance and stability margins in micro/nanopositioning applications. In this paper, hysteresis and creep compensators have been designed and implemented as feedforward controllers in a real-time experiment. With the suggested feedforward compensators, the hysteresis and creep nonlinearities have been reduced to 2.3% from 23% and 0.3% from 6% respectively. To further enhance the reference tracking performance, a robust
$\mathrm{H}_{\infty}$
feedback controller is combined with the feedforward hysteresis and creep compensators to achieve the better positioning accuracy. Three different cases are investigated in this study: open loop configuration without any compensator, open-loop configuration with the feedforward hysteresis and creep compensators and finally closed-loop configuration with a feedback controller in the presence of feedforward compensators. Achieved results indicate that a better positioning accuracy is attained with the suggested feedforward/feedback control scheme.