Research On Measurement Technology Of Ship Deformation Based On Strapdown Inertial System

Ship deformation is an important factor affecting the accuracy of shipborne equipment,which is of great significance for the construction of a unified attitude reference of the ship.The ship deformation measurement technology based on inertial information matching has high measurement accuracy,is easy to implement,and can measure the ship deformation angle dynamically in real time,thus becoming a hot topic at present.In this paper,the dual-fiber strapdown inertial navigation system is used to measure the ship deformation angle.The ship deformation measurement technology based on the inertial measurement matching method is studied in depth.A ship deformation measurement software system based on Visual Studio 2017 software is designed to measure four inertial measurements.Four kinds of inertial measurement matching are analyzed and studied.Aiming at the problems of the ship deformation model mismatch and the measurement noise of the inertial system is not single in the measurement process,the corresponding solutions are proposed,which lay the foundation for further research on the measurement technology of ship deformation.The main contents of this paper are summarized as follows:Firstly,the ship deformation model is analyzed and researched from two aspects:physical model and mathematical model.On the one hand,the finite element model of the ship and the ship flow field model were constructed by Ansys Workbench software,and the wave load was simulated,and the pressure and deformation of the ship were analyzed by applying it to the ship model.The true deformation of the ship under the influence of wave load is obtained through the fluid-solid coupling method.On the other hand,a mathematical model is established for the static and dynamic deformation of the ship,which lays the foundation for the later study of the inertial measurement matching method.Secondly,the inertial measurement matching method is studied.The angular velocity matching method,velocity+angular velocity matching method,attitude matching method and velocity+attitude matching method are analyzed theoretically and algorithmically derived.Then the drift characteristics of gyro and accelerometer are analyzed.Then the ship’s deformation angle is modeled as static deformation angle and dynamic deformation angle.Then the ship’s deformation angle is modeled as static deformation angle and dynamic deformation angle.Through simulation test,it is verified that the measurement accuracy of the inertial measurement matching method can reach 30",which can effectively measure the ship’s deformation angle.Thirdly,a strong tracking kalman filter algorithm based on attitude matching is proposed to reduce the error caused by the uncertainty of the model in the ship deformation measurement system.The algorithm can adaptively adjust the fading factor online to fade the data channel,even when the filtering reaches the steady state,the filtering gain can still be adjusted to reduce the filtering estimation error.Aiming at the error caused by non-Gaussian noise experienced by inertial instruments,a maximum correlation entropy kalman filtering algorithm is proposed.The algorithm uses the maximum correlation entropy as the optimal criterion,which can not only capture ordinary second-order statistical information,but also obtain higher order statistics.The simulation results show that the proposed algorithm is effective and the estimation accuracy can be improved.Fourth,based on the MFC platform of Visual Studio 2017 software,a ship deformation measurement software system based on a dual-fiber strapdown inertial system is designed.A semi-physical simulation test of ship deformation measurement using a three-axis rocking platform is used to measure the static deformation angle and dynamic deformation of the ship.The simulation experiments were carried out to verify the feasibility of the algorithm proposed in this paper,and to prove the feasibility of using inertial system to measure ship deformation and the effectiveness of ship deformation measurement software system.