Integrated Energy-Optimal Control for Underactuated Surface Vessels via Adaptive Sliding Mode and High-Order Extended State Observer with Thrust Allocation

This paper explores the problem of trajectory tracking control for Underactuated Surface Vessels (USVs) subject to unknown environmental disturbances and other uncertainties. The proposed controlled system consists of an Adaptive Sliding Mode Control (ASMC), an High-Order Extended State Observer (HO-ESO), and an energy-optimal Thrust Allocation (TA) algorithm between the propeller and the rudder. An HO-ESO is introduced to estimate unmeasured system states and unknown external disturbances, enhancing the control system’s sustainability. Moreover, to improve the precision in trajectory tracking and mitigate the conventional sliding mode control’s chattering phenomenon, an adaptive control law is designed to dynamically adjust control gains. Furthermore, unlike conventional control methods, input control signals are typically assumed to be ideal. An energy-optimal thrust allocation algorithm is developed to convert control signals from the controller into practical reference commands for the actuators. By establishing a nonlinear optimization problem, the proposed TA scheme helps to reduce the total amount of energy consumption while ensuring physical actuator constraints and maintaining satisfactory trajectory tracking performance. This paper also performs a stability analysis based on Lyapunov theory, which proves that all tracking errors in the closed-loop system are bounded and stable. Simulation studies, which are conducted in the Matlab-Simulink application, has validated the superiority of the proposed integrated controller, in terms of its tracking accuracy, disturbance rejection capability, and energy efficiency compared with existing methods.