ADAPTIVE CONTROL OF LINEAR TIME-VARYING PLANTS: A NEW CONTROLLER STRUCTURE.

Abstract

The model reference control and model reference adaptive control problems are considered for a class of linear time-varying plants with bounded, piecewise smooth parameters. A controller structure that solves the model reference control problem, with zero tracking error, in the case of smooth slowly time-varying plant parameters is introduced. When the plant parameters are unknown, the robust adaptive law is used to adjust the controller parameters and establish both boundedness of all signals in the adaptive loop and good tracking properties, provided that the smooth time-variations of the plant parameters are sufficiently slow and the minimum time between discontinuities is large enough. It is shown that when the plant parameters become constant, the tracking error converges asymptotically to zero.