MIMO direct adaptive control with reduced prior knowledge of the high frequency gain

This paper addresses the problem of designing model-reference adaptive control for linear MIMO systems with unknown high-frequency gain matrix (HFGM). The concept of hierarchy of control is introduced leading to a new control parametrization and an error equation with triangular HFGM, which allows a sequential design of the adaptation scheme. Significant reduction of the prior knowledge about the HFGM is achieved, overcoming the limitations of the known methods. A complete stability and convergence analysis is developed based on a new class of signals and their properties. Exponential stability is guaranteed under explicit persistency of excitation conditions