New robust adaptive control system using multiple regularization parameters

The design of a discrete-time model reference robust adaptive control system for a plant in the presence of bounded disturbances is investigated. The system uses a robust adaptive algorithm with multiple regularization parameters. This algorithm belongs to the class of leaky integration methods; thus the designed regularization parameters correspond to σ in the σ-modification approach. It is shown how to determine these regularization parameters theoretically such that minimization of the parameter error is attained in the presence of the disturbances, and it is not necessary for the upper bound of the disturbances to be known a priori. Furthermore, persistent spanning is ensured, regardless of the size of the disturbance.