Abstract
Recently, various nonlinear compensation systems have been proposed for tracking the reference input fastly and finely. Using a nonlinear element, these systems can give a good response to a step reference which conceals overshoot and has fast rising time. However, the systems are constructed under hypothesis that the plant's parameters are accurate and time-invariant. In practice, it is difficult to obtain plant's parameters accurately, and it is usual that the plant changes with time and operating state. Then, the effect of parameter variation must be considered.
In this paper, we propose a model tracking system. This system is composed of a nominal model and a tracking system with a robust compensator. The nominal model produces an ideal response to the nominal plant. If the actual plant is equal to the nominal plant, the response of the nominal model tracking system will be the same as one of the nominal model. In use of H∞ control theory, the robust compensator is designed to gurantee system stability, to attenuate the effect of paremeter variation and to track the ideal response under paremeter variation.
As an application, we design the nominal model tracking system to the speed control system. From computer simulations We can show that the nominal model tracking system is very effective.
