Improving the Robustness of Trajectory Tracking Dynamic Surface Control

Dynamic surface control (DSC) methods use first order filters to compute the derivatives of stabilizing functions developed through backstepping. The performance of trajectory tracking DSC controllers can become degraded when disturbances are sudden and large. Here, we demonstrate that the robustness of DSC-based trajectory tracking controllers can be improved by augmenting the first order filters with a hyperbolic tangent vector function. Actuator constraints are included. The uniform semiglobal practical exponential stability of the augmented closed-loop control system is proved. Trajectory-tracking simulations of an autonomous underwater vehicle demonstrate the performance improvement achieved with the proposed approach.