Unified treatment of internal model principle based adaptive control algorithms

A number of adaptive control algorithms are summarized here for the control of unknown linear discrete time plants with unknown deterministic disturbances. Adaptive implementation of the internal model principle is used for asymptotical cancellation of the deterministic disturbances. The use of the certainty equivalence principle for implementation of these algorithms can be shown to result in a certain type of unmodelled dynamics error for each of these algorithms. A unified analysis of these algorithms is given under a common framework of unmodelled dynamics. With suitable modification of the parameter estimation algorithm, the global convergence and stability of these algorithms are established without the requirement of the persistency of excitation condition. Some simulation results are provided for support of the analysis. © 1991 Taylor and Francis Ltd.