Abstract
Simple adaptive control (SAC) scheme has its main advantage that a relatively few parameters are estimated on-line to guarantee stability through implicit adaptation. The stability is usually guaranteed by adding a parallel feedforward compensator (PFC) to SAC system so as to realize the almost strictly positive realness (ASPRness) of the plant. This paper is concerned with an evaluation problem of ASPRness for the simple adaptive control scheme. The effect of model-plant mismatch and structured uncertainty on ASPRness is investigated. Further, PFC design scheme based on the derived evaluation method is also derived. The results allow us to evaluate the ASPRness and also give the role of different tuning parameters in the design of PFCs for delay processes with structured uncertainty. The effectiveness of the proposed method is examined through numerical simulation and the good control performance is obtained in spite of large process parameters uncertainty.
