Control and guidance of a hovering AUV pitching up or down

In this paper, we present an approach to control an autonomous underwater vehicle in the vertical and the horizontal planes while pitching down or up (θ = ±π/2). Such a capability is explored in MARES, a small-sized, torpedo-shaped hovering AUV with four degrees of freedom. Despite the fact that roll angle is not controllable, we find a guidance law that makes the vehicle reach any point in the horizontal plane while maintaining the vehicle in the vertical position.