Research On The Calibration Technology Of Fiber-optic IMU Under Temperature Environment

As the core component of the fiber optic inertial navigation system,fiber-optic IMU has the characteristics of small size,no start-up process,low energy consumption,large dynamic range and strong impact resistance,and has been widely used in aerospace,weapon navigation,robot control,oil drilling,radar and other fields.In the practical application,the components of fiber-optic gyroscope and accelerometer in the fiber-optic IMU will be affected by the working environment temperature,which will lead to the decrease of accuracy.In this paper,according to the actual situation,the calibration technology research of the fiber-optic IMU in the temperature-variable environment will be carried out,and the temperature error model and compensation technology research of the fiber-optic IMU will be established.Fiber-optic gyroscope and quartz flexible accelerometer are the two most important components in fiber optic inertial assembly.Starting from the principle of FOG and accelerometer,the influence mechanism of temperature on IMU was analyzed,and the actual influence of temperature environment on the internal components of FOG and accelerometer was determined.First,the temperature characteristics of the main performance indexes of the inertial system are analyzed and the temperature correlation is determined as the basis of the temperature error model.Afterwards,the experiment method of separate calibration was used to calibrate the fiber-optic IMU in the process of temperature change.The temperature characteristics of each calibration parameter of fiber optic IMU in different environments are analyzed by using the calibration experimental results.A more suitable modeling method is determined after comprehensive consideration.The zero deviation and scale factors of FOG and accelerometer are identified.Among them,The temperature and the rate of temperature change of the FOG are identified.By determining the order and coefficient of the compensation model,the most suitable mathematical model is established.Based on the temperature model of the previous stage,the mathematical temperature model compensation is carried out for each calibration parameter.The experimental data are used to analyze the situation before and after compensation,and the comparison results show that the temperature model can achieve a better temperature compensation effect,and has a significant improvement effect on the calibration of fiber-optic IMU in the temperature environment.During the compensation process,it was found that the temperature model had a weak effect on the scale factor compensation of the accelerometer.Therefore,for this kind of situation,a "piecewise modeling" modeling scheme was designed,in which the unobvious mathematical relation was segmented into an individual with obvious relation,and each segment was identified separately.After the compensation verification,the compensation effect is very significant,which has high application value.