Guidance of Underwater Vehicles With Cable Tug Perturbations Under Fixed and Adaptive Control Systems

This paper is concerned with the study of guidance of underwater vehicles subject to cable perturbations due to action of currents and harmonic waves. The general case involves a variable cable length that is usually deployed during vehicle tactics. Control situations are considered, namely, trajectory tracking and position regulation when the reference trajectory for the vehicle is given beforehand. To this end, a control system is designed with adaptive features. A great effort is made in this paper for modeling the cable dynamics in a quasi-stationary state. This model can serve the operator to compensate for the perturbation automatically during teleoperation. Moreover, in the adaptive systems, the perturbation is filtered automatically without having to embed the cable model in the controller design. Effects of the cable perturbation on the control system in adaptive and fixed systems are analyzed comparatively. Proofs of convergence to the tracking error to a residual set are given rigorously in the framework of total stability. The features of the controlled behavior are illustrated by numerical simulations in a case study in six degrees of freedom.