For underactuated unmanned surface vehicles (USVs), the uncontrollable nonzero sway velocity leads to the sideslip phenomenon, bringing difficulties in tasks with high attitude requirements. This article proposes a path following control algorithm for underactuated USVs, which can reduce the sideslip angle on a curved path. A novel path following approach by controlling two points on the USV is developed, one of which is used for guaranteeing position error convergence, and the other is used for an optimization problem to reduce the sideslip angle. In order to reduce the influence of the sway velocity on the curved path, a surge speed regulator is designed to adjust the desired surge speed according to the curvature of the desired path at the current position. Numerical simulations and experiments are carried out, and the results show that the sideslip angle is significantly reduced while the position error exponentially converges to zero.

This article addresses the robust trajectory tracking control strategy of differential-driven unmanned surface vessels, with the propeller servo loop taken into consideration. The proposed strategy takes duty cycles of propeller motors as control input and thereby can be directly applied in practice without any modification. Compared to the existing methods, the proposed method provides the framework of position control considering propeller servo loop and improves robustness to external disturbances. The controller design procedure is divided into three stages through backstepping technique. Disturbance observers are constructed to provide estimations of composite disturbances, which guarantee robustness in the presence of external disturbances and model uncertainties. An auxiliary system is introduced to handle the input saturation of duty cycles. With a linear growth condition of the output of propeller motors, a rigorous proof is presented to show tracking errors are uniformly ultimately bounded. Simulation and experiments illustrate the effectiveness of the proposed control strategy.

In this paper, the infinite-dimensional port-Hamiltonian modelling and control problem of a flexible beam actuated using ionic polymer metal composite (IPMC) actuators is investigated. The port-Hamiltonian framework is used to propose an interconnected control model of the mechanical flexible beam and the IPMC actuator. The mechanical flexible dynamic is modelled as a Timoshenko beam, and the electric dynamics of the IPMCs are considered in the model. Furthermore, a passivity-based control-strategy is used to obtain the desired configuration of the proposed interconnected system, and the closed-loop stability is analyzed using the early lumped approach. Lastly, numerical simulations and experimental results are presented to validate the proposed model and the effectiveness of the proposed control law.

This study uses a port-Hamiltonian framework to address trajectory tracking control for unmanned surface vessels (USVs) under unknown disturbances. A passivity-based sliding mode controller is designed, integrating adaptive disturbance estimation and an RBFNN-based uncertainty estimator. Stability is rigorously proven, and simulations confirm superior tracking performance, strong disturbance rejection, and accurate uncertainty estimation.