Trailing Suction Hopper Dredger Motion Model Identification Research

The ship motion models are the key to research ship maneuverability,design ship motion control system and exploit ship motion simulation simulator.Since the 1930 s,many experts and scholars have devoted to the research of ship motion models.Within this several decades,based on different mechanisms modeling,several kinds of ship motion model frames are established and they are gradually become perfect.The established ship motion model frames include many unknown model parameters,It is difficult to guarantee the accuracy of model parameters obtained through theoretical calculations or experiments, so many people obtain the ship model parameters by the method of system identification.This paper is relied on the high-tech research project of Technology Department of Jiangsu Province—“The research and application of marine engineering ship dynamic positioning system’s key techniques”,a large trailing suction hopper dredger as the reference object,bases on the ship motion model frame which has been determined,identify this ship’s parameters,and gain an ideal effect.The paper studies with a clear direction and value in use, which mainly includes the following aspects:Firstly, this paper derives the general ship motion mathematical model,and analysis parameters which need to identify,the three main factors of environmental disturbance effects—wind, wave, flow are also being constructed with model equations, and shows how to calculate their disturbance forces and moments.According to the characteristics of the trailing suction hopper dredger,establish propeller force model,rudder force model, anti-thrust model of bow spray and rake arm drag force model.In order to gain the system’s input data and output data which is necessary to the parameters identification experiment,decoupling ship motion equation,design actual ship surge test and sway-yaw test,collect raw data.wavelet analysis theory is applied in the denoising of test data,according to different experimental data,select the appropriate threshold and different wavelet bases and wavelet, pretreatment original signal with wavelet threshold denoising,reliable data are gained.To overcame the lack of extend kalman filter algorithm in ship motion model identification,this paper put forward a improve algorithm,this algorithm’s parallel identification structure can reduce the error in the process of ship motion model linearization,thus effectively reduce the error sources of traditional algorithm.Depend on trailing suction hopper dredger to design system simulation test,new algorithm results,traditional algorithm results and measured value were compared separately,verify the validity of identification results, improved algorithm is superior to the traditional algorithm as well.