Research On Heave Measurement Method Based On Inertial Navigation

Because of the abundant resources in the sea,people pay more and more attention to marine development.It is of great practical significance to study the heave motion of ships and submarines on the sea for the accuracy of exploration information and the safety of completing the task.In order to reduce the interference of complex sea surface environment and improve the detection accuracy,this paper studies the measurement of heave motion information for sonar carriers performing tasks on the sea surface.This paper designs a method of heave information measurement based on inertial navigation principle.Inertial measurement unit is used for measurement,the specific force information of carrier attitude and altitude is calculated,a digital filter is added to filter out the interference information,and a phase compensation method is designed to solve the phase problem of the digital filter,which realizes a high precision heave information measurement.The main research contents are as follows.Firstly,the principle of heave measurement is analyzed.The relevant coordinate system is established,and the characteristics of heave motion are deduced according to the wave model;the principle of heave measurement based on SINS and SINS is introduced;several factors affecting heave measurement are proposed,including the instability of height channel,oscillation period,arm effect error and amplitude-phase deviation caused by digital filter,and a heave measurement scheme is designed.Secondly,the carrier attitude estimation algorithm is studied.Based on the principle of extended Kalman filter and the direct quaternion method,the attitude estimation of the carrier is realized;the heave motion test is simulated by three-axis turntable,and the attitude estimation results are given.Thirdly,a digital filter for heave measurement is designed.By analyzing the principle and classification of digital filters,IIR digital high-pass filters are selected;several key technical indexes of IIR digital filter are introduced and its design process is described;according to the influence of several technical indicators and the characteristics of heave signal,the optimal filter for heave measurement is designed,and the test results are given.Finally,a phase compensation method of digital filter based on frequency estimation is designed.Because the leading phase caused by IIR digital filter depends on the signal frequency,a frequency estimation algorithm based on FFT and modified is designed;the relationship between phase and frequency of IIR filter is deduced,and the phase is balanced by cascaded allpass filter;the design algorithm is applied to measure the heave signal under different conditions,and its performance is analyzed.