Yaw-Guided Trajectory Tracking Control of an Asymmetric Underactuated Surface Vehicle

In this paper, suffering from both complex uncertainties and underactuations, accurate trajectory tracking control problem of an asymmetric underactuated surface vehicle (AUSV) is first addressed by guiding yaw dynamics which are free of persistent excitation (PE). Using nested coordinate transformations, the AUSV is formulated in a cascade structure consisting of translation and rotation subsystems with complex uncertainties. Finite-time uncertainty observers (FUOs) are devised to exactly estimate transformed uncertainties, and enable separation principle in controller and observer syntheses. By virtue of creating yaw-guided dynamics, rotation tracking is shaped to stabilize yaw and sway tracking discrepancies, simultaneously, in collaboration with yaw controller. Nominal dynamics of translation tracking errors are globally asymptotically stabilized by surge-control synthesis using cascade analysis and Lyapunov approach, and thereby contributing to global asymptotic stability of the entire translation-rotation tracking system. Eventually, an FUO-based yaw-guided tracking control (FUO-YTC) scheme of an AUSV with complex uncertainties is established. Simulation studies demonstrate remarkable performance.