Modeling and Control of Industrial ROV’s for Semi-Autonomous Subsea Maintenance Services

Remotely Operated Vechicles (ROV’s) takes a big part in the installation, maintenance and inspection of offshore subsea energy activities, such as inspections of Oil & Gas and wind energy pipelines and cables. By improving the ROV automation the operational cost can be significantly decreased as well as improving the inspection quality. This study examines an industrial ROV, where the investigations include modeling of a real industrial prototype, which is then linearized and used for Linear Quadratic Regulator (LQR) development. The results are validated both based on non-linear model simulations. Furthermore, the LQR controller is compared with the existing built-in heading and depth PID controllers, where it is shown that the LQR controller both gives an improved closed-loop transient performance and rejects noise better than the built-in controller. It is concluded that the ROV prototype has an acceptable physical design but that the automation could potentially be improved by adding a MIMO control scheme such as the proposed LQR controller.