Adaptive and robust stabilization of feedforward nonlinear systems driven by symmetric and non-symmetric dead-zone inputs

The stabilization of feedforward nonlinear systems subject to hard-input nonlinearities is a challenging problem due to the presence of input uncertainties. This paper deals with adaptive control of a class of feedforward nonlinear systems driven by unknown dead-zone inputs. The unknown dead-zone input nonlinearity is assumed to be either symmetric or non-symmetric. The control design is based on the combination of the invariant-manifold stabilization technique with the classical adaptive and robust compensation methods. Simulation results showed that the presence of the dead-zone inputs in the system dynamics can be handled even for arbitrary large dead-zone parameters.