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.