Trajectory Tracking with Prescribed Performance for Underactuated Underwater Vehicles under Model Uncertainties and External Disturbances

This paper addresses the tracking control problem of 3-D trajectories for underactuated underwater robotic vehicles. Our recent theoretical results on the prescribed performance control of fully actuated nonlinear systems are innovatively extended on the control of the most common types of underactuated underwater vehicles, namely, the torpedo-like (i.e., vehicles actuated only in surge, pitch, and yaw) and the unicycle-like (i.e., vehicles actuated only in surge, heave, and yaw). The main contributions of this paper concentrate on: 1) the reduced design complexity; 2) the increased robustness against system uncertainties; 3) the prescribed transient and steady-state performance; and 4) the minimal tracking information requirements. A comparative simulation study points out the intriguing performance properties of the proposed method, while its applicability is experimentally verified using a small unicycle-like underactuated underwater vehicle in a test tank.