Abstract
Servo system that is tracking the reference input fastly and finely is demanded in industries. For the realization of this, many control methods using an nonlinear element have been presented. The characteristic of servo system designed by these mothods is improved in contrast to linear ones. But these systems are too sensitive to parameter variation, so the effect of variation must be considered.
To solve this problem we proposed Nominal Model Tracking System. In this method, a robust compensator is designed with H∞ control theory. As a result, the robust system that is less sensitive to parameter variation is obtained. But since we didn't consider the structure of parameters in the method where all variation is regarded as a single variation of plant's transfer function, the variation that doesn't exist is included. Therefore the scope of robust stability may be narrowed.
In this paper, We discuss Nominal Model Tracking System again with μ-synthesis control theory. Through considering structured variation, we expect that the new system will have robust performance in a wider scope of parameter variation.
As an application, we use the method to the speed control of motor system. From computer simulations, we can show that the method is effective.
