MULTIRATE ANALYSIS AND DESIGN OF VISUAL FEEDBACK DIGITAL SERVO-CONTROL SYSTEM

This paper addresses the analysis and design of digital motion control system with machine vision as a feedback measurement in the servo loo p. The camera vision is modeled as a discrete time-delayed sensor. A m ultirate formulation is proposed based on the fact that vision update rate is slower than the digital servo-control update rate and is analy zed through the lifting technique which converts the periodic time var ying multirate system to a time invariant one. Some interesting proper ties of this specific multirate system are found and are utilized in c ontrol system design. An l-1 norm optimal control problem is formulate d to minimize the maximum time domain error, which has direct connecti on to camera field of view and mechanical tolerance. A numerical examp le is given to demonstrate the presented methods.