Path following control for articulated intervention-AUVs using geometric control of reduced attitude

Abstract

An articulated intervention autonomous underwater vehicle (AIAUV) consists of the jointed body of a snake robot equipped with thrusters for hovering and faster propulsion. The slender, articulated body can be used as a floating manipulator arm for subsea intervention. In order to extend the reach and operation time of the AIAUV, energy-efficient methods for longdistance travel are needed. This paper proposes a path-following control method for AIAUVs moving in 3D which reduces the use of thrusters by using them only for forward propulsion. The direction of travel is controlled by curving the body using its joints. As a first step, a control law for tracking of a reduced attitude is developed for a general system with two control torques, and shown to give asymptotic tracking of a time-varying reference reduced attitude. This control law is then used indirectly to provide references for the joint angles of an AIAUV, in order to control its pointing direction. By combining this with a line-of-sight (LOS) guidance law, a method for following straight paths is obtained. Simulation studies show that the method succeeds in making an AIAUV converge to and follow the desired path.