On Performance Improvement of Adaptive Tuners

Here we depart from the standard stabilization objective of adaptive control and assume that for the plant to be controlled a parametrization of the regulator insuring closed-loop stability is known. The structure, dynamic order and number of adjustable parameters of the compensator are at the designer's disposal and no assumptions, except linearity are imposed on the plant. We propose an on-line tuning procedure for the controller parameters intended to improve performance and such that global stability is preserved. Performance of the adaptive system is evaluated in two ways: deriving uniform bounds on the sup value of the tracking error; giving conditions under which RMS performance index decreases when adaptation is turned on.