System Identification and Dynamic Positioning of Ships

Abstract

Dynamic Positioning of vessels has an important role in the safety of operations in the industries where the use of marine vessels is involved. Therefore, it is necessary to have an adequate implementation of system identification and accurate control methods for the vessels.

The objectives of this work are: Implementing a mathematical model of the vessel, performing system identification, developing accurate control methods, and comparing these methods under different conditions of operation.

The model was simplified discarding the drag coefficients and then its behavior was measured. The system identification took place by using the inputs and response of the closed loop system. PID, LQ Optimal control with integral action and MPC with integral action were selected as control methods. These methods were then compared under different benchmarks.

The simplified model behaves adequately. For the unconstrained control signals, LQ is the best option, whereas for the constrained case, MPC was better. The PID controllers are computationally cheap, however, very sensitive to wind disturbances which means that they need to be tuned constantly.