Two-time-scale digital controller design for a position servo system

In this paper we propose a new digital controller for a position servo system. The controller is an observer based controller which takes advantage of the two-time-scale structure of the motor. Only some knowledge of the mechanical and electrical time-constants, and not a detailed mathematical model or exact parameter values, are required to implement the controller and that the closed loop system performance specifications can be met reasonably well under the lack of detailed modeling. The transient mismatch phenomenon which occurs for this class of designs is fully discussed and a sufficient condition is obtained to guarantee that such a mismatch will not occur.