Robust Control of Autonomous Remotely Operated Vehicles at Exposed Aquaculture Sites

This article presents two adaptive nonlinear controllers for robust velocity and heading control of a remotely operated vehicle (ROV) navigating in exposed aquaculture sites. The controllers are designed to enable autonomous traversal of an aquaculture net pen using a net-following guidance algorithm in the presence of significant environmental disturbances. Each controller is tailored for different application scenarios, hence for different models of the ROV. The first is suitable for slow-speed maneuvers, while the second applies to cases involving aggressive maneuvers. This model is more complex due to the additional Coriolis force nonlinearities that appear in the second scenario. For the closed-loop system with the first controller, we prove uniform global exponential stability. For the second controller, we establish uniform asymptotic stability under a necessary and sufficient condition of persistence of excitation. Furthermore, both controllers achieve estimation of the (constant) ocean currents. In addition, our theoretical findings are reinforced by simulation and experimental results that illustrate the good performance of our controllers. The experimental tests were realized on an industrial underwater robot. Furthermore, the first controller was successfully tested at a full-scale aquaculture site under realistic operational conditions.