Adaptive nonlinear H∞ control for processes with bounded variations of parameters-general relative degree case

A new class of adaptive nonlinear H_∞ control systems for processes with bounded variations of time-varying parameters, is proposed in this manuscript. Those control schemes are derived as solutions of particular nonlinear H_∞ control problems, where unknown system parameters are regarded as exogenous disturbances to the processes, and thus, in the resulting control systems, the L² gains from system parameters to generalized outputs are made less than γ(>0). The control schemes are shown to be suboptimal to some H_∞ cost functionals (or certain differential games), when the high-frequency gains are time-invariant