Research On Measurement Method Of Motion State Parameters Of High-Speed Moving Target In Bore

Motion attitude of projectile in bore is an important research content of interior ballistic test.It is an important test basis for ammunition design,strength checking,bore jamming fault analysis and barrel life evaluation.However,due to the high-speed movement of projectile accompanied by high temperature,high pressure,high-speed,high-frequency vibration and strong sound,strong light and other physical and chemical transient phenomena,the test environment is very bad.Aiming at the difficulty of measuring the motion parameters of projectiles in bore,this paper studies and analyses the echo signal by establishing a theoretical model,in order to find a set of testing scheme for obtaining the motion information of high-speed moving targets in bore by microwave interferometer.On the basis of interior ballistic mechanics and combined with the actual micro-motion of projectile in bore,the model of high-speed motion of projectile in rifle gun is established.The transformation law of longitudinal motion of projectile in bore is obtained by processing radar Doppler signal with time-domain extremum method and short-time Fourier transform method.Then,by comparing and analyzing the results of signal processing with three time-frequency methods: short-time Fourier transform,Wigner-Ville transform and improved Hilbert-Huang transform,a method suitable for obtaining detailed micro-Doppler information is found.Finally,aiming at the actual signal of velocity missing section caused by external environment interference,the particle filter-based method is used to repair and optimize the velocity curve.At the same time,the above-mentioned analysis method is used to process the actual signal and obtain the actual motion state information of high-speed projectile in bore.The results show that if the longitudinal motion information is obtained,the short-time Fourier transform can process the projectile echo signal with small proportion of micro-Doppler energy with the highest accuracy and smooth curve;if the micro-motion information needs to be obtained from it,for the projectile echo signal with large proportion of micro-Doppler energy,the improved Hilbert-Huang transform and Wigner-Ville transform are effective,and the Hilbert-Huang transform is effective.The instantaneous frequency information obtained by this method is more detailed and the mean error is the smallest,which is 10 times smaller than that by STFT method.The swing characteristics of projectiles in bore can be quantitatively obtained by processing and analysis,and the swing frequency error is within the range of 1 kHz.Compared with the experimental data of different groups,the unbalanced degree in gun barrel can be judged.