Research On MIMU-assisted Related Interferometer Direction Finding Correction Algorithm For UAV

Airborne direction finding technology has always played an important role in the military and civilian fields.It can be used for intelligence reconnaissance in the military,and can be used for spectrum detection,radio monitoring and maritime rescue in civil.In recent years,the mini-rotor drone has developed rapidly.Its excellent hovering ability and low cost have also made it becoming an ideal carrier for airborne direction finding systems.It has gradually become a research hotspot and has also received scholars at home and abroad.Since the birth of radio direction finding technology,many direction finding systems have been developed.Among them,the relevant interferometer direction finding system is most suitable for airborne direction finding.Based on the nature of radio waves traveling in a uniform medium in a straight line at a uniform speed,the direction finding device is used.Receiving the incoming signal and calculating the phase difference between the baselines,and finally obtain the azimuth information of the radiation source relative to the carrier according to the direction finding algorithm.It can be known from the principle that the stability of the direction finding platform will affect the accuracy of the system.However,due to its small size,the micro drone is more susceptible to vibration(such as motor rotation,gusts,etc),causing the wing of the fuselage to swing,which will reduce The accuracy of the direction finding system mounted on it.In response to this problem,this article mainly does the following:First,the airborne correlation interferometer direction finding system model is established.From the antenna configuration design,standard library establishment and related matching algorithms,the traditional correlation interferometer direction finding system is designed and improved to adapt to the microrotor drone.The factors affecting the accuracy of the direction finding system are analyzed theoretically,and the drone-related interferometer direction finding system established by the subject is verified and analyzed through simulation experiments.Secondly,using the first-order vibration model of the drone as the error source,an error model of the drone-related interferometric direction finding system in a vibrating environment is established,and the degree of influence of the hovering vibration of the micro-rotor drone on the interferometer direction-finding system is analyzed.Aiming at the vibration error of the drone direction finding system,a Miniature Inertial Measurement Unit(MIMU)is proposed to assist the drone-related interferometer direction correction algorithm.This algorithm belongs to an active correction algorithm.As an auxiliary source,the vibration attitude of the drone in hovering state can be obtained in real time,and the direction finding result can be compensated by the correction algorithm,which can realize the accurate direction finding of the drone in hovering state.Finally,in order to solve the problem of excessive noise of the gyro itself in the MIMU,the error suppression method of the MIMU mounted on the drone is studied.The MIMU assisted UAV direction finding correction algorithm proposed in this paper is an active correction algorithm.The accuracy of the auxiliary source directly affects the effectiveness of the correction algorithm.In this paper,the error modeling of the gyroscope is firstly performed,and the random error of the gyroscope is analyzed using the Allan variance method.Based on the motion state of the drone in hover state,an improved attitude algorithm based on the accelerometer is proposed.The three-axis attitude misalignment angle of the carrier compensates the attitude information through Kalman filtering to achieve the error suppression of MIMU.