A finite-time adaptive intervention controller for underwater vehicle manipulator systems

Underwater vehicle manipulator systems (UVMSs) control in intervention tasks is challenging because of the coupling effects between the system. To address this challenge, we propose a novel finite-time adaptive intervention controller (FTAIC) to control vehicle trajectories of a UVMS in intervention tasks without prior knowledge of the underwater manipulator. The coupling effects are modeled as a static component produced by gravity and buoyancy and a dynamic component produced by velocity and acceleration. First, the terminal sliding surface is exploited to guarantee the finite time convergence. Then, we design an adaptive law to estimate the static component and obtain more accurate dynamics of the UVMS system, and use a nonlinear disturbance observer to estimate the dynamic component and external disturbances. Subsequently, the proposed control law with the coupling effects and external disturbances compensation is given, and we prove the stability of the whole system. Extensive simulations are conducted on the Simurvplatform and demonstrate the better performance of the proposed method compared with that of conventional adaptive and robust controllers, with a fast convergence speed and smaller tracking errors. Experiments are demonstrated on the fly arm autonomous underwater manipulator system (FAAUMS), and illustrate wide promise of the FTAIC in real applications.