Visual Servoing Based on Multirate Control and Dead-time Compensation

Abstract

This paper presents a visual servoing of robot manipulator based on intersample disturbance rejection with switching scheme and dead-time compensation. First, multirate intersample disturbance rejection algorithm is reviewed, which was proposed by authors for general digital control system with restricted sampling frequency. Second, the novel feedforward scheme is proposed with open-loop estimation and switching function, which enables the disturbance rejection without any sacrifice of the closed-loop characteristics. Third, new precise formulation of delay problems in visual servoing is established as the image processing latency, the difference between sampling period of camera signal and control period of joint servo system, and delay of inner-loop joint servo system. By introducing the workspace controller and nonlinear perspective transformation, the proposed intersample disturbance rejection controller becomes applicable to the visual servoing problem of 2 DOF manipulator with moving object points. Finally, the advantages of the proposed control system are verified through simulations and experiments.