Hybrid retrospective-cost-based adaptive control using concurrent parameter estimation

We present an adaptive control methodology that requires no plant modeling information. The method is based on a cumulative retrospective cost adaptive control algorithm, which is a direct adaptive control algorithm for stabilization, disturbance rejection, and command following when partial plant modeling information is available, specifically, the first nonzero Markov parameter, the relative degree, and estimates of nonminimum-phase zeros. The same adaptive algorithm is used online to estimate the required modeling information. By merging these processes into a single architecture, the resulting hybrid adaptive control algorithm requires no prior modeling information. The method is demonstrated on several illustrative disturbance rejection and command following problems, where the plant can be either minimum or nonminimum phase, and stable or unstable.