Research Of Inertial Measurement Method For Hull Deformation Under The Condition Of Model Uncertainty

When the ship is sailing on the sea,due to the influence of the environment,The deformation angle of the ship hull makes the ship equipment unable to work normally,and the precision of the equipment is reduced.Therefore,it is a hot topic to accurately estimate the deformation of ship hull and reduce its influence on the equipment.The inertial device of hull deformation measurement not only has the advantages of high measurement accuracy,low requirement of measurement,but also can measure the hull deformation in real time.It has become the most potential measurement method in ship hull measurement at present.In this paper,the deformation of the hull is measured by using the output data of the fiber strapdown inertial navigation systems.According to the angular velocity information can directly reflect the deformation information of the hull.So the angular velocity matching method is used to estimate the deformation angle of the hull in this paper.To solve the problem of uncertain model parameters,two methods are proposed in this paper.For the linear model,the interactive multiple algorithm is proposed;For the nonlinear model,the parameters of the model are estimated by the method of parameter online estimation.The simulation models are established for these two methods.The effectiveness of the proposed methods are verified by theoretical simulation and physical test,which lay the foundation for the further research on the measurement of hull deformation.The main contents of this paper are as follows:Firstly,this paper introduces the basic knowledge of the inertial matching method to measuring the deformation of the hull and the working principle of the strapdown inertial navigation system.The Kalman filter algorithm and the CKF algorithm based on angular rate matching are introduced.The linear model and nonlinear model of the hull deformation are deduced,and the simulation results show that the Kalman filter algorithm and the CKF algorithm can effectively eliminate the interference of gyro drift and other factors,and achieve the optimal estimation of hull deformation angle.Secondly,the actual conditions have great effect on the hull deformation,which makes the model parameters change,which reduce the estimation precision of ship dynamic deformation.In order to solve the problem of parameter uncertainty in linear model,thispaper presents the interactive multiple model algorithm,which is divided the model parameters into several intervals,respectively performing Kalman filter,then the hull deformation is estimated through the data fusion.However,the static deformation is less affected by sea state,and has a great relationship with the ship structure and the thermal effect of the sun.When the static deformation is Quasi-static process,the static deformation angle can be tracked effectively.In order to solve the problem of parameter uncertainty in nonlinear model,this paper presents the method of parameter online estimation,which can estimate the parameters of the dynamic deformation using the output data of the gyroscope,and then use the CKF algorithm to estimate the hull deformation.The simulation results show that the two methods can improve the estimation accuracy of hull deformation and reduce the influence of uncertain parameters on the estimation results.Finally,according to the structural characteristics of deformation measurement system and the ship itself,In this paper,a physical test scheme is designed based on the optical fiber strapdown inertial navigation system,which is developed by the laboratory.According to the limitation of the experimental conditions,this paper designs a semi-physical test for the linear model,and the effectiveness of the interactive multiple model algorithm for hull deformation measurement is verified by physical experiments.