Robust Control of A Novel Small AUV With Titlting Tunnel Thrusters

This work presents the pose stabilization and trajectory tracking control of a novel small AUV having tilting in-body tunnel thrusters using the Sliding Mode technique. The tilting tunnel thrusters enable the vehicle to maneuver in ways that are impossible in traditional underwater vehicles with fins, such as nose-down diving maneuver, lateral motion, and simultaneous motion along two axes. We further represent the vehicle attitude using quaternions, which, unlike Euler angles, do not have singularity problems. We propose a robust controller using a simple Sliding Mode technique to mitigate external disturbances and model parameter uncertainties. The stability analysis of the system with the proposed controller is presented. Quasi-Sliding mode technique is employed to avoid chattering, which can be detrimental to the health of servo actuators. Using numerical simulations, we show satisfactory performance in both pose stabilization and trajectory tracking in the presence of external disturbances and model parameter uncertainties.