Development of a 5 degree-of-freedom towfish and its control strategy

This paper describes the development of a five degree of freedom towed underwater vehicle designed for condition monitoring of undersea pipelines. Its innovative design, with 6 fins actuated by 5 motors adding heave and sway capabilities to the yaw, roll and pitch movements possible in traditional designs, is explained. The parameters influencing the stability and the design in general are analyzed. A Control strategy for this design of highly coupled movements and control modes encompassing all the operational scenarios, are presented.