The design of dynamic ship positioning control systems using stochastic optimal control theory
Michael John Grimble, RON J. PATTON, Dalton Wise · Optimal Control Applications and Methods · 1980
Abstract The design of dynamic ship positioning control systems and their associated wave filters is considered. The control problems and the basic components in the system are discussed first. The model of the vessel is then described, since this plays an important role in the design of the Kalman filter which is used to estimate the low frequency motions of the vessel. The model involves both high and low frequency subsystems. The total linearized model for the vessel is represented by state equations, and simulation results are given to illustrate the performance of the Kalman filter. A comparison with a notch filter is also presented. The design of the optimal control system using LQG stochastic control results is considered. The operation of the system under various operating conditions is illustrated. Schemes involving the extended Kalman filter are then described. These enable more realistic non‐linear models of the plant to be employed within the filter. This is shown to be unnecessary in the case of the low frequency ship model. However, the extended filter may be useful to track varying wave conditions (using parameter estimation) as represented in the high frequency model. Two extended filtering schemes are presented for this case.