Leader-Follower Motion Control for a USV Tracking a Hybrid ROV in Subsea Cable Inspection Missions

Heterogeneous marine robotic systems combining an unmanned surface vehicle (USV) and a hybrid remotely operated vehicle (HROV) are increasingly used for subsea cable inspections. During operations, the USV typically acts as a follower platform, supplying power and providing a communication link to the HROV via an umbilical cable. This finite tether length constrains the relative motion between the vehicles, so the USV must closely track the HROV to prevent abrupt variations in cable tension that could compromise operational stability. However, due to uncertainties in the HROV position measurements and environmental disturbances, such as wind, waves, and currents, the USV is prone to significant heading oscillations and large tracking errors, which greatly increases the risk of sudden tether-tension fluctuations. To address these issues, an improved particle filter (IPF) is proposed for HROV state estimation, which incorporates feasible-position and velocity constraints to enhance estimation accuracy, thereby providing a smooth, reliable target reference for USV tracking. Additionally, an adaptive weight model predictive control (AWMPC) method is developed, in which a fuzzy logic-based weight tuner adjusts the weight matrix coefficients according to real-time tracking errors to improve tracking adaptability under varying conditions. Furthermore, an extended state observer (ESO) is designed to estimate and compensate for external disturbances, further enhancing tracking accuracy and robustness. Simulation results demonstrate that, with the proposed AWMPC-IPF-ESO framework, the USV could accurately track the HROV with smooth motion. Compared with basic MPC, the mean tracking distance error is reduced by about 27.61%, and the heading-oscillation amplitude by 65.72%, significantly decreasing the risk of abrupt changes in cable tension.