Research On The Key Technology Of Array Micro-inertial Navigation System Performance Optimization

In high dynamic flight,UAVs need high precision positioning information,especially attitude information.Compared with the Global Navigation Satellite System(GNSS),the Inertial Navigation System(INS)can calculate the attitude information in real time.For micro-UAV,the high-precision platform inertial navigation system cannot be used generally,and only the Micro Electro Mechanical Systems(MEMS)Inertial Measurement Unit(IMU)can be used to obtain the inertial information.At present,the accuracy of a single MEMS IMU is difficult to meet the actual navigation requirements.In view of the above shortcomings,the positioning accuracy of UAV can be effectively improved by using multiple MEMS IMU,based on the appropriate fusion method to collect the inertial data of each group of IMU at the same time.This thesis focuses on the key technologies of MEMS inertial array navigation system,Considering the difficulty in measurement of the sub-IMU position to the main-IMU of the inertial array,the calibration method of the installation error angle and the arm length of the inertial array is designed;aiming at the probable problems of over range in the single MEMS gyroscope during navigation,the fusion method of calculating the angular velocity based on the arm acceleration and the output angular velocity of the gyroscope is studied,aiming at the inertial data fusion In this thesis,the particle filter method is used.The specific research contents are as follows:Firstly,the thesis designs the method of calibration of the installation error angle of the inertial array and the arm length.When the inertial array is initialized,the inaccuracy of the installation error angle and the length of the lever arm is commonly seen.This thesis presented a method of calibration of the installation error angle of the inertial array.This method can not only measure the attitude error of the X and Y axes of the sub IMU relative to the main IMU,but also use the two different groups of attitude information of the inertial array to get the attitude errors of Z axis relative to main-IMU.For the course angle error of the main IMU,the position information of the sub-IMU relative to the main-IMU is measured based on the principle of the lever arm.This method makes the inertial array rotate at a certain angular velocity on the rotating platform,and uses the angular velocity and acceleration information output by the sub-IMU to calculate,so that the position information of the sub-IMU relative to the main-IMU can be obtained.Experimental results show that this method can be used to calculate the arm length of sub-IMU relative to the main-IMU effectively,and the error is smaller than 0.2%.Secondly,the thesis studies method of calculating angular velocity based on the acceleration of pole and arm.Aiming at the problem that the accuracy and range of single gyroscope cannot be balanced,this thesis proposes a method to calculate the angular velocity based on the acceleration of lever arm.Firstly,the sub-IMU is divided into groups of three which can output the angular acceleration information respectively,and the angular velocity information is obtained by integrating the output angular acceleration.Then,the angular velocity at the last moment is used as the weight to fuse with the angular velocity output by gyroscope.The angular velocity information of the inertial array is obtained.The simulation results show that when the angular velocity of gyroscope exceeds the range,the angular velocity can effectively follow the attitude of the carrier.Then,the thesis designs an inertial data fusion method based on particle filter.Aiming at the fusion of angular velocity and acceleration of inertial array,a fusion algorithm of angular velocity and acceleration based on particle filter is studied in this thesis.In this method,the difference between the attitude and velocity information of the sub-IMU’s strapdown solution and the main strapdown solution is taken as the weight,and the angular velocity and acceleration information are fused.When the weight of a sub IMU is close to zero,it indicates that the IMU is in fault.At this time,the navigation information of the main-IMU is used to modify the sub navigation information,so as to improve the overall navigation performance.The simulation results show that this method can reduce the location error by twice compared with that of a single IMU.Finally,the thesis designs the algorithm based on the Kalman Filter(KF)External observation navigation system to modify the inertial navigation based on array inertial system,discusses the KF state equation and measurement equation establishment method,and based on the KF array inertial navigation correction system correction method.Simulation results show that this method can effectively modify the array navigation system.