Perception And Location Of External Equipment Of Spacecraft Hypervelocity Impacted In Noise Environment

With the increasing number of human space activities,a large number of spacecraft that have failed to be used have become space debris.High-speed space debris seriously threatens spacecraft's on-orbit safety.Space debris is divided into large fragments,small fragments and hazardous fragments according to its size.At present,the large debris is evaded through on-orbit maneuvers,and the small debris is protected by installing a protective structure.On the other hand,dangerous debris that is difficult to maneuver and evade and difficult to defend is proposed.Real-time perception,positioning and damage recognition.Among them,the on-track sensing system based on acoustic emission has received extensive attention due to its low resource consumption,strong environmental adaptability,ability to perform allweather monitoring of spacecraft,and high system reliability.Spacecraft complex environment in orbit,on-orbit awareness system will be inorbit background noise,sudden transient noise interference affect the system's perception and positioning accuracy.The main application object of on-track sensing technology is the spacecraft wall plate structure,and a large number of equipments are often connected outside the spacecraft,and a thickened structure such as a porthole edge is added to the tank body stiffening plate,and is directly impacted by the space debris compared to the sealed capsule body.These locations are less harmful to the spacecraft when they are impacted by space debris.Therefore,it is necessary to conduct the perceptual identification of the hypervelocity impact events of the external structure.Based on the ground simulation data,this paper studies the simulation method and characteristics of noise and external structure impact interference signal,the method of identification of impact perturbation of cabin equipment under noisy environment and the method of cabin collision under noisy environment.(1)Obtain the main background noise,transient noise and external structure impact interference signals of spacecraft in orbit.The ground noise simulation test and hypervelocity impact test of the spacecraft's aluminum alloy stiffened panels were performed.The resulting interference signals were subjected to amplitude-frequency analysis to obtain the frequency spectrum characteristics of the interference signals.The research results show that the background noise signal frequency is lower than 200 k Hz,and the transient noise frequency is lower than 300 k Hz.(2)External structure ultra high-speed impact interference signal recognition research.This paper bases on the traditional signal spectrum analysis and identification method,based on adaptive methods such as SVD decomposition filtering,empirical mode decomposition,principal component analysis and SVM classification algorithm to distinguish different types of interference signals from waveform and spectrum perspectives.The relationship between cut-off frequency and impact velocity of different thicknesses and different structures was analyzed.According to the above analysis results,the acquisition method of the perception recognition threshold and the self-adaptive identification method of the perturbation interference of the cabin equipment in the noisy environment are identified,and the recognition accuracy is over 95%.(3)Research on positioning of hypervelocity impact signal source in noisy environment.The positioning of acoustic emission sources can also be affected by the noise environment,resulting in reduced positioning accuracy.Firstly,this paper studies the traditional method of locating the threshold time difference;according to different signal-to-noise ratios,it superposes the various types of operational noise signals and hypervelocity impact signals obtained from the experiment,and analyzes the relationship between the downtime and the arrival time error of different positioning gates.The data obtained from the simulation test of guns were used to simulate the source location of the spacecraft's reinforced tanks,and the relationship between the relative errors of the subgingival and the positioning of different positioning doors was obtained.The combination of median filtering and highfrequency IMF component reconstruction reduces the adverse effects of background noise on positioning.The simulation results show that the reconstructed signal positioning relative error does not exceed 1%,which effectively improves the cabin collision impact positioning accuracy in noisy environments..