A study of determining an adaptive control input without using a parallel feedforward compensator

This article describes an approach to determine a modified adaptive control input which realizes an almost strictly positive real (ASPR) plant without a parallel feedforward compensator (PFC). In a simple adaptive control (SAC) theory, several output feedback based control techniques can be applied to the plant satisfying ASPR characteristics. However, real plants do not often satisfy this characteristics. To solve this problem, several PFC design methods have been proposed so far. Most PFC design parameters are generally adjusted by acquiring an empirical knowledge of designers. This article focuses on this situation. If a relative degree of the plant is two, ASPR plants can be designed by modifying an adaptive control input. We perform the effectiveness of the proposed method by some numerical simulations.