Fractional-order Robust Controller for High Precision Galvanometer Scanner

A new fractional-order controller design method is proposed for highly parameters uncertain system. This controller, based on fractional-order, considers of the specification in both frequency-domain and time-domain simultaneously for galvanometer scanner system. Due to the existence of nonlinear friction, the galvanometer scanner can be approximated as system with uncertain parameters in the low frequency region. In this design procedure, Quantitative Feedback Theory (QFT) is adopted to constrain the frequency domain characteristics of the system, to guarantee the robustness of system and minimize the effect of nonlinear friction in the low frequency region. The integral of time and absolute error (ITAE) criterion is selected to ensure the desired step response performance in the time-domain. Simulation results are shown to demonstrate the feasibility of this method for the galvanometer scanner position tracking.