Research On Key Technologies Of Automatic Tracking System For Rocket Sled Ejection Test

With the improvement of military forces worldwide,the air military force,as one of the core forces,has attracted much attention.Accordingly,the fighter pilots who are the main part of air combat are also receiving increasing attention.In order to ensure the life safety of aircrews,many countries have invested numbers of resources and funds to conduct research on aviation protection lifesaving system.The ejection seat is an important part of the aviation protection lifesaving system.And it is a key device of emergency departure which can save lives of fighter pilots.A large number of tests should be carried out on the ejection seat at each stages of the research and design to ensure its reliability,stability and safety.The rocket sled ejection test is a simulation test which is most close to the real environment of the seat ejection.In the test,the rocket sled equipped with an ejection seat is driven by the huge power produced by the rocket booster at high speed on the rail.When it reaches a certain speed,the ejection seat is popped out.So the rocket sled ejection can be used to simulate the scene that the seat ejected from the high-speed fighter exactly.To analyze the whole process of rocket sled ejection test well,it is necessary to obtain image date which responses the test results intuitively with high-speed camera usually used to record the whole test process.At present,the acquisition of image data mainly depends on the manual tracking and captured by the testers.It is influenced by the subjective perception of the testers,and the effect of sonic boom is easy to cause jitter during the test process.Especially in the supersonic test environment,it may cause tracking failure due to the speed of human reaction cannot keep up with the speed of the rocket sled.In order to obtain accurate and effective image data of the rocket sled ejection test,some key technologies of automatic tracking system for rocket sled ejection test are studied in this paper.The main contents are summarized as follows:1.Structure design of photo-theodolite:On the premise of meeting the relevant technical indicators of the automatic tracking system for rocket sled ejection test,the photo-theodolite are analyzed from the aspects of optics,mechanics and mechanical structure and the selection of main instruments is determined.Then a compact miniaturized photo-theodolite is designed.2.Target detection and tracking for rocket sled ejection test:The rocket sled ejection test need to switch tracking target during the tracking process.Therefore,the whole tracking process can be divided into three parts:the detection and tracking for rocket sled,ejection seat and fighter pilot.The corresponding detection and tracking methods for each part are proposed.While the automatic switching and accurate tracking of target are realized.3.Photo-theodolite calibration:There is no collimation axis for the photo-theodolite designed in this paper.Therefore,photo-theodolite calibration is divided into two parts:camera calibration and photo-theodolite structure calibration.An out-of-focus camera calibration method with phase-shifting wedge grating array is proposed to obtain accurate calibration results.And photo-theodolite structure calibration is realized by using the camera extristric parameters and the corresponding angle parameters of the theodolite.4.Trajectory calculation of ejection target:The inconvenient measurement angle parameters are set as unknown parameters,and then the two-station intersection measurement can be converted into condition adjustment with parameters.The RWTLS method is used to simplify the calculation process.Meanwhile,the angle parameters obtained in the case of alignment imprecisely can be optimized by dealing with the coordinate conversion relationship between the ideal initial coordinate system and the actual initial coordinate system of the photo-theodolite.Besides,the distribution of observation stations is also analyzed and optimized.