UDE-based Nonlinear Path-following Control of Autonomous Underwater Vehicles With Multiple Uncertainties and Input Saturation

This paper proposes a novel UDE-based nonlinear path-following (PF) control scheme for the underactuated autonomous underwater vehicle (AUV) with multiple uncertainties and input saturation. Firstly, to overcome the drawback of dependence on the accurate mathematical model, the unknown time-varying sideslip angular speed in the error dynamic model is treated as kinematic uncertainty, and the linear superposition of parameter uncertainties, environmental perturbations, and other unmodeled dynamics is regarded as lumped dynamic uncertainty. Both kinematic and dynamic uncertainties are estimated and compensated by the designed uncertainty and disturbance estimators (UDEs). Secondly, a novel augmented backstepping controller based on the estimates generated by UDEs is proposed to achieve PF control of the underactuated AUV. The nonlinear tracking differentiator (NTD) is adopted to prevent the “explosion of complexity” inherent in the traditional back-stepping method, and the auxiliary dynamical system is utilized to solve the issue of input saturation. Lastly, the stability analysis of the entire enclosed-loop framework is presented. Simulations and comparative analyses are presented to demonstrate the effectiveness and robustness of the presented strategy.