A new variable structure controller for affine nonlinear systems with non-matching uncertainties

The problem of output tracking in SISO uncertain non-autonomous nonlinear systems is treated in this study. It is shown that a nonlinear system experiencing non-matching disturbances and uncertainties can be transformed to a form similar to the normal form. Then, a novel variable structure controller with disturbance estimation and parameter adaptation is presented. This controller, while preserving the robustness properties of sliding control, avoids a sliding mode and generates a continuous control signal, which results in close output tracking.