CONTINUOUS I O ROBUST-CONTROL OF SISO TIME-VARYING SYSTEMS/

In this paper output tracking problem of time-varying systems is inves tigated. A system under consideration contains time-varying parameters which may change very fast and may be subjected to high-order nonline ar disturbances. A robust controller requiring only input-output measu rement is proposed. The control guarantees at least stability of unifo rm ultimate boundedness which can be made arbitrarily close to asympto tic stability through choosing a design constant. The resulting contro l is continuous, uniformly bounded, and designed by a recursive mappin g procedure. The only information of unknown systems required by the r obust control approach are the bounding function on the magnitude of n onlinear disturbances and the bounds on the parameters and their deriv atives; which represent the distinct feature of the proposed result. T hat is, time-varying parameters are not restricted to be either slow t ime-varying or of known structure. (C) 1997 Elsevier Science Ltd.