Equidistance target‐following controller for underactuated autonomous underwater vehicles

Autonomous Underwater Vehicles (AUVs) play a crucial role in marine biology research and oceanic natural resources exploration. Since most AUVs are underactuated they require sophisticated trajectory planning and tracking algorithms. The purpose of this paper is to develop a new method that allows an underactuated AUV to track a moving object while constraining the approach to a direction tangent to the path of the target. Furthermore, the distance at which the AUV follows the target is constrained, reducing the probability of detection and unwanted behavior change of the target.

First, a kinematic controller that generates a trajectory tangent to the path of the moving target is designed such that the AUV maintains a prescribed distance and approaches the target from behind. Using a Lyapunov based method the stability of the kinematic controller is proven. Second, a dynamic sliding mode controller is employed to drive the vehicle on the trajectory computed in the first step.

The kinematic and dynamic controllers are shown to be stable and robust against parameter uncertainty in the dynamic model of the vehicle. Results of numerical simulations for equidistant tracking of a target on both smooth and discontinuous derivatives trajectories for a variety of relative initial positions and orientations are shown.

The contribution of this research is development of a new method for path planning and tracking of moving targets for underactuated AUVs in the horizontal plane. The method allows control of both the direction of approach and the distance from a moving object.