Visual servoing based on intersample disturbance rejection by multirate sampling control-time delay compensation and experimental verification

Multirate sampling controllers are proposed for digital control systems, where the speed of the A/D converters is restricted to be slower than that of the D/A converters. The proposed feedback controller assures perfect disturbance rejection at M intersample points in the steady state. The proposed method is extended to systems with time delay, and the compensation method is proposed based on the observer including time delay model. Next, the scheme of repetitive control is proposed based on the open-loop estimation and switching function, which enables the rejection of periodical disturbance without any sacrifice of the closed-loop characteristics. Finally, the proposed controllers are applied to a visual servo system by introducing the workspace controller and nonlinear perspective transformation. The advantages of these approaches are demonstrated by simulations and experiments using a robot manipulator.