Design and stability of indirect adaptive control for nonlinear system

Structures are developed for the control and estimation parts of the indirect adaptive scheme which are more appropriate for time-varying plants. In contrast to the usual pointwise schemes, the new controller structure can meet the control need. In addition, for successful estimation, the overall plant is not restricted to varying slowly with time. The new estimator and control law are combined using the certainty equivalence principle to develop an indirect adaptive control scheme meeting the control objective for plants with time-varying parameters whose fast varying parts are of known form and unknown parts are slow in the mean. The stability of closed-loop system was proved, and the convergence of the state vector to a residual set around the equilibrium, whose size can be set by the choice of several design constants is demonstrated by the simulation results.