Research On The Ship Motion Control Simulation System Base On Parameter Identification

With the using the resource of the ocean, ships for transportation are developed tohigh-speed and large-sized, traffic pressure and safety problem are increasing, so it isimportant to research ship motion control. It is dangerous and expensive to researchship motion control if we use real ships, but we will solve these problems if we getship motion control simulation system. Because of ship motion control simulationsystem, we can speed up the development of some ship motion control products suchas autopilot. It provides good research and test environment to research ship motioncontrol algorithm and test autopilots, reduces the number of experiment times and theresearch expenses. By combining the parameter identification method and the optimalcontrol theory, a new ship course control algorithm is brought forward.First of all, ship motion mathematical models are created, including the basichydrodynamic model, ship’s linear state space model, the Nomoto’s1st-Order modeland interferences (wind, wave and flow) mathematics model. For the ship motionmathematical model, z rudder experiment, constant rotation experiment and theinterference simulation experiment are done.Second, classical PID course control algorithm, optimal PID course controlalgorithm，fuzzy course control algorithm and the new course control algorithm arebrought forward. Parameters of the classic PID course control algorithm are calculatedfrom the traditional PID parameters analysis method, so the optimal PID coursecontrol algorithm has adaptive abilities. Parameters of the optimal PID course controlalgorithm are calculated from the optimal control algorithm. Fuzzy course controlalgorithm is not designed with ship model, so it has some robustness. The new coursecontrol algorithm is designed with ship motion state-space model. We get the basiccontrol algorithm from the optimal control algorithm. We solve the problem that thebasic control algorithm can not restrain the constant interferences by using differentialform of the input variables. We use observer to obtain the required data of inputvariables. Finally, the new course control algorithm is completed. The simulationresults of the above three algorithms are given out. The results of simulation haveshown that the new course control algorithms proposed above are effective and havegood performances and adaptive abilities.Third, indirect model reference adaptive method and least squares algorithm withexponential forgetting are applied to estimate the parameters in the ship motionmathematical models. Indirect model reference adaptive method is used to estimatethe parameters of the K-T model. The least squares algorithm with exponentialforgetting is used to estimate the parameters of the K-T model and the ship motionstate-space model. The results of simulation have shown that the two algorithmsproposed above are effective and have good performances, the least squares algorithmwith exponential forgetting is better. Finally, this paper realized the ship motion control simulation system, and givedsimple introduction to each part. The simulation results of the ship motion controlsimulation system have shown that the simulation system proposed above is effectiveand has good performances.