A Novel Disturbance Observer Design Method for Time Delay Systems with Application to Nano Manipulations

In this paper, a novel disturbance observer (DOB) design method for time delay systems is proposed to compensate system uncertainties and unknown disturbances in nano manipulating systems. A Modified Disturbance Observer (MDOB) structure for time delay systems is utilized, where the design of low pass filter (LPF) in MDOB is formulated to a mixed sensitivity optimization of infinite dimensional systems. This problem is then solved by Skew-Toeplitz based approach. Furthermore, the constraint conditions of LPF can be realized by the selection of weighting functions. Finally, experimental validation of the proposed DOB design method is performed on a piezo-actuated nano-positioning stage, where the experimental results demonstrate the effectiveness of the proposed approach.