Robust and adaptive nonlinear control using dynamic surface controller with applications to intelligent vehicle highway systems

In this dissertation, results in robust and adaptive control of nonlinear systems with mismatched uncertainties are presented in the framework of the Dynamic Surface Controller (DSC). The proposed controllers are intuitively appealing and use low-pass filters to avoid explicit differentiation of the nonlinearities, thus avoiding the complexity that gives rise to the problem of "explosion of terms" in other non-linear control schemes. Stability results are obtained for the DSC on systems with non-Lipschitz nonlinearities and uncertainties, guaranteeing semi-global exponential stability for regulation and arbitrarily small bounded tracking error for bounded trajectories. In the area of nonlinear adaptive control, an adaptive DSC is developed to tackle control of uncertain nonlinear systems where the uncertainties are in the form of unknown constant parameters. Semi-global stability results are obtained for regulation and set-point control. Robust and adaptive DSC are then applied to the problem of longitudinal vehicle control in an automated highway system, consisting of platoons of ground vehicles traveling at highway cruising speeds. Closed-loop controllers are developed for vehicle speed control and intra-platoon spacing control, accompanied by simulation results.