Control of an under actuated hovering-type autonomous underwater vehicle for moving to a point and following a circular path

A hovering autonomous underwater vehicle usually has at least four thrusters which gives it the ability to propel in all directions. By decreasing the number of thruster, the AUV will have more room to accommodate for other devices. However, the AUV would become an under actuated system. From literature, there are various works had been studied to control an under actuated AUV. However, many of the works only considers either vertical or horizontal aspects of the AUV motion and single type of trajectory problem. In this paper, proportional and proportional-integral controllers are proposed to solve two trajectory problems of moving to a point and following a path in 3 dimensional spaces. Results show that the implementation of the control improves the response of the system to be much faster and reduces steady state error so that desired output is achieved.