Modeling, Analysis and Control of Underwater Vehicle SROV

Abstract: A new type of Remotely Operated Vehicle (ROV) has been designed by Marin Mätteknik (MMT) in cooperation with Reach Subsea and Kystdesign AS; the Surveyor ROV. Although MMT is successfully using the SROV in day-to-day operations, no mathematical model describing the system has previously been derived. In this thesis project, a mathematical model describing the SROV is developed through system identification techniques. Experiments to facilitate parameter estimation of the model are designed and consequently performed. The gathered data sets are investigated to determine how well they are suited for parameter estimation. Estimation of the continuous-time model parameters are carried out using a Kalman filter running on the input-output data obtained through the experiments. Comparisons between this method and results obtained through a subspacebased identification Matlab method are performed. Model validation is carried out using numerous performance measures. The thesis has shown that a coupled LPV model may be a feasible approach to the modeling problem, and also makes suggestions that could possiblyimprove on the results. As an alternative to the current control system, simulations of closed-loop responses of the identified system model using a Model Predictive Control (MPC) structure are undertaken and presented. The simulations show that good performance is achievable using the MPC lgorithm. Noticeably, the current control system has difficulties attenuating deviations from angular velocity set points. The MPC scheme has been shown to effectively suppress such control errors in simulations.