A Novel Dual-Observer Based Control Scheme for Nano-positioning Systems with Output Delay

In this paper, a novel dual disturbance observer based control (DOBC) method is presented to achieve unknown-periodic disturbance rejection of the nano-positioning stages with output delays. In the control structure, an auxiliary observer is employed to extract the state of the disturbance, while a key information observer is developed to estimate the disturbance frequency. To stabilize the augmented system, a feedback controller is further designed, where sufficient stability conditions are derived though Lyapunov-Krasovskii functions. Simulations and real time experiments on a piezoelectric-actuated nano-positioning stage with output delay are conducted, where the disturbance frequency is well predicted for the purpose of cancellation.