Research Of The Ship Deformation Estimation Algorithm Based On Angular Rate Matching Method

This paper researched the estimation algorithm of ship deformation which was based on the angular rate matching method.In particular,this paper studied two contents,they were inertial measurement matching method based on linear model and the inertial measurement matching method based on nonlinear model.In the inertial measurement matching method based on linear model,firstly,the ship deformation linear model was established,and then to optimize the model based on the experimental data.Besides,this paper analyzed observability about the linear model of angular rate matching method,and pointed out the effects which was caused by unobservable of the system on the deformation angle measurement.At the same time,two groups simulation of linear model have been carried out,and these simulation included three times simulation,they were the ship swaying with a small angle under motion in a straight line,typical swing under the motion in a straight line and typical swing ships under circular motion.Simulation results showed that the algorithm had a good stability,and the estimation precision of static deformation angle and dynamic deformation angle can be reached0.3'and0.5'.Based on the situation that the research of inertial measurement of hull deformation still confined to the linear model,In this paper,two inertial measurement unit installation angle error for varieties of reasons maybe exist in actual situation,inertial measurement matching algorithm based on nonlinear model was studied.Firstly,Ship deformation nonlinear model was established,and then two kinds of typical nonlinear filtering for the nonlinear model were given.and the estimation precision of two kinds of nonlinear filtering were analyzed in comparison.In order to verify estimate effectiveness for nonlinear model of the EKF,UKF,and CKF filter.In this paper various simulation was also carried out respectively under the different conditions of system simulation.The simulation results showed that,EKF,UKF and CKF can effectively estimate the deformation angle in the weak nonlinear system.and with the augmentation of the nonlinear system,the estimation precision of EKF had a significant reduction,But both UKF and CKF showed good stability.This results suggested that,UKF and CKF have good estimation accuracy for both linear model and nonlinear model.In addition,the paper also made a compare UKF with CKF in these estimation accuracy,and the simulation included two contents:when installation error angle of inertial measurement unit in the course reached to30~?,and when installation angle error of inertial measurement unit in three directions was30~?,10~?,10~?.In order to guaranteed the accuracy of the results of simulation,simulation had been carried out 50 times by UKF and CKF filter respectively,Through statistical results can be found that,both UKF and CKF can effectively estimate the deformation angle in strongly nonlinear model,but CKF's estimation precision is higher than UKF's,and its convergence speed was also faster than the UKF's.At the same time,it also proved that the estimation precision of UKF and CKF in theoretical analysis is correct.