The Research Of Multi-UAV For Passive Target Location And Tracking Technology

In recent years,the rapid development of UAV technology,has been widely used in various fields.Among them,the self localization of UAV platform and the problem of UAV target location have been the hot research topic both here and abroad,and they are widely used in daily life,aerospace,military and other fields.The self positioning of UAV platform is essential for the completion of complex tasks.Passive target location and tracking problem is also the development direction of target tracking.Based on the requirement of practical environment,the problem of improving the accuracy of UAV's self localization is studied,and then the multi-UAV is applied to the passive target location and tracking scene.The main work and achievements of this paper are as follows:(1)Firstly,the application and research background of UAV are introduced,and the research status of UAV navigation technology is briefly introduced.Then,aimming at the problem of inaccurate positioning of single GPS in small civil UAV in the outdoor flight near the ground without significant increase in cost and system complexity,by installing a plurality of GPS receiver in UAV,a data fusion method based on weighted average of calman filter is proposed to improve UAV self localization accuracy,the feasibility and effectiveness of the method are verified by static ground experiment and dynamic flight experiment.(2)This paper studies the method of target location based on the direction finding passive location system of multi-UAV.Firstly,the principle of the algorithm of multi-UAV direction finding cross target location is analyzed.Then a small four rotor UAV as the object,according to the information of the target image captured by the airborne CCD canera,the angle information of UAV relative to the target is calculated by offset extraction and coordinate registration,and the validity of the algorithm is verified by experiments.At last,the factors that affect the precision of the positioning system are discussed based on GDOP(geometric precision factor).The simulation results show that the direction finding and positioning system of multi-UAV requires high precision of angle measurement;At the same time,increasing the baseline length of UAVs can effectively improve the accuracy of target localization.(3)In order to solve the problem that the multi sensor measurement data is not synchronized in the passive target location and tracking problem,the time calibration algorithm of airborne sensor is studied.First introduces the basic principle and application field of time calibration problems,then the time factors that may affect the positioning accuracy in the passive target location and tracking system of multi-UAV are analyzed,we propose a time drift calibration algorithm based on interpolation method,and realize the time registration of multi-UAV observation dat,so as to reduce the positioning error caused by time synchronization.(4)In view of the model nonlinear problem caused by the observation in the passive tracking of moving targets,the unified measurement equation of each UAV after coordinate system registration is given,an algorithm for moving object tracking based on unscented kalman filter(UKF)is also derived in this paper,on the basis of the use of sensor measurements prior information,using the fusion algorithm based on the distributed fusion strategy to fuse the local tracking results of each UAV,a more accurate target tracking trajectory is obtained,which provides a technical reference for the engineering application of passive location and tracking in airborne platform.