Improved Performance Adaptive Control Under Standard Mrac Assumptions

In this paper, an adaptive controller with improved transient and steady-state performance using parameter mismatch compensation and high-order tuning is presented. As in previous designs, the use of a properly designed signal, compensating for the effects of parameter mismatch on the output error, leads to "arbitrary" performance improvement. However, unlike previous designs based on first-order (classical) tuners, high-order tuning is necessary in order to avoid the effect of terms due to initial conditions on the output error. This constitutes a strong motivation for the use of high-order tuners in adaptive control which so far, were considered as more complicated alternatives to the classical first-order tuners. The proposed controller also provides robustness enhancement in the presence of bounded disturbances and/or a class of unmodeled dynamics or in the event of an adaptation switch-off end, as in classical model reference adaptive control, guarantees the exponential convergence of all errors to zero in the presence of sufficiently exciting reference inputs.