The underwater swimming manipulator (USM) is a snake-like, multi-articulated, underwater robot that is equipped with thrusters. One of the main purposes of the USM is to act like an underwater floating base manipulator. As such, it is essential to achieve good station-keeping and trajectory tracking performance for the USM by using the thrusters and by using the joints to attain the desired position and orientation of the head and tail of the USM. In this 'paper, we propose a sliding mode control (SMC) law, specifically the super-twisting algorithm with adaptive gains, for the trajectory tracking of the USM's centre of mass. A higher-order sliding mode observer is proposed for state estimation. Furthermore, we show the ultimate boundedness of the tracking errors. We demonstrate the applicability of the proposed control law and show that it leads to better performance than a linear PD-controller.

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The articulated intervention AUV (AIAUV) is an underwater swimming manipulator (USM) with intervention capabilities. Station-keeping and trajectory tracking are essential for the AIAUV to be able to move in confined spaces and to perform intervention tasks. In this paper we propose using the generalized super twisting algorithm, which is an extension of the regular super-twisting algorithm, for the trajectory tracking of the joint angles, position and orientation of the base of the AIAUV in 6DOF. Furthermore, we show the ultimate boundedness of the tracking errors. We also demonstrate the applicability of the proposed control law and compare the performance with the regular super-twisting algorithm with adaptive gains.

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