Robust model reference adaptive controller for single variable non-linear plants

A new general scheme for robust model reference adaptive controller (MRAC) is proposed for single variable nonlinear plants and can be applied without any modifications to single variable nonlinear plants, both time-invariant and time varying in nature. The proposed robust MRAC is based on the estimation of the difference between the linear time-invariant model plant parameters and actual plant parameters that show nonlinearity and time varyingness. The approach used in this work is an extension of the approach commonly used to develop MRAC for a linear time-invariant plants. The boundedness of the signals and stability of the plant with the proposed robust MRAC in use are achieved by using Lyapunov´s direct method. Simulation results are used to demonstrate the effectiveness of the proposed MRAC.