Simulation and Realization of Linear Insects Different Movement Forms Radar Echo Model Based On Point Target

Transcription

1 , pp hp://dx.doi.org/ /ijca Simulaion and Realizaion of Linear Insecs Differen Movemen Forms Radar Echo Model Based On Poin Targe Xuqiang Lang 1, Jialin Hou* 1 and Kai Tang 2 1 College of Mechanical and Elecronic Engineering, Shandong Agriculural Universiy, Taian, China 2 Sae Key Laboraory of Mechanical Engineering and Conroling, Beijing Insiue of Technology BeiJing, China [email protected], [email protected], [email protected] Absrac In allusion o he imporance of insecs movemen forms deecion, his paper pus forward an linear insecs movemen forms deecion mehod using Micro-Doppler radar. This paper have a poin model classificaion on linear insecs body and ge he vibraion characerisics of each model poin in differen movemen forms hrough experimens. I combines wih Doppler echo equaions of poin model vibraion, and builds he linear insecs Doppler echo model. This paper deec differen movemen forms of enebrio molior in larva period wih real-ime Doppler radar daa acquisiion sysem, compare he movemen echo ime-frequency diagram of differen movemen forms obained by STFT wih he simulaion. I aims o verify he raionaliy of building he linear model of he insecs using model poins and he feasibiliy of applying he Micro-Doppler o he real-ime deecion of insec movemen forms. Keywords: microwave, Micro-Doppler, concealed pess, ime-frequency analysis 1. Inroducion Sudies of insec movemen forms can increase human's undersanding of insec movemens and grasp heir living habis beer. The scienific daa of insec movemen forms under differen environmenal condiions can guide he fuure developmen of bionic micro-robo. The Micro-Doppler radar can make he deecion o he hidden pess and also accuraely orienae concealed pess, which can improve he perinence and scienificiy in pes conrol [1, 2]. Targe moion Doppler deecion echnology based on radar is a new echnology rising in recen years, he principle of which is ha he refleced wave, generaed when radar wave radiaes o he arge, will be modulaed by arge s movemen, and he modulaion wave conains he Doppler signals generaed by arge s movemen [3]. By analyzing he radar echo Doppler signal characerisics and using Time-Frequency Analysis, he arge s curren movemen form can be exraced, such as he direcion of moion, speed, acceleraed speed and ampliude and so on [4]. Micro-Doppler is a special form of radar Doppler. I mainly refers o he mechanical vibraion or roaion exising in he objec or par of i in he main Projec "Simulaion and Realizaion of Linear Insecs Differen Movemen Forms Radar Echo Model Based On Poin Targe" Suppored by Modern Vegeable Indusry Technology Sysem Innovaion Team Building of Shandong Province, China.[ SDAIT ]. ISSN: IJCA Copyrigh c 2014 SERSC

2 direcion relaively, and i is shown in he form of frequency shif sidelobe on he frequency specrogram of radar echo [5-7]. Radar beam is disseminaed hrough he elecromagneic wave, so i canno be influenced by he environmen and ligh so as o work day and nigh for he sensor. Radar beam can pass hrough he obsacle, deec he moion of he hidden objec and ge he informaion of i accuraely. In a word, he echnique for he objec deecion, based on radar Micro-Doppler effec, will have a brigh fuure in he safey proecion, diaser assisance, deecion of moving objec and he sudy of hidden objec. In his paper, based on poin arge moion model, we build a simple movemen forms echo equaions of linear insecs. Wih enebrio molior being he arge, we simplify he body wih muliple model poins o obain heir vibraion performance of differen movemen forms, We can also combine wih poin arge radar echo equaions, build radar echo model of differen movemen forms of enebrio molior, and hen, obain he ime-frequency diagrams of body echo in differen movemen forms by simulaion wih MATLAB. The body echo daa can be recorded by Doppler echo signal acquisiion sysem and he ime-frequency diagram of movemen echo can be obained by STFT, comparing wih he simulaion resuls. Is purpose is o verify he raionaliy of building he linear model of he insecs using model poins and he feasibiliy of applying he Micro-Doppler o he real-ime deecion of insec movemen forms. 2. Doppler Movemen Model of Linear Insecs 2.1 The model of linear insecs Every par of body in he process of linear insecs movemen has a muual resricion and a very complex srucure. Referring o moion analysis of snake robo, in his paper, he linear insec bodies are simplified o N secions plane rod sysem [8], as shown in Figure 1. Because he lengh of each secion is far less han he radar deecion disance, he movemen of each secion can be simplified as a model poin movemen. The analysis of specific movemen forms of linear insecs can be decomposed ino movemen characerisics' analysis of each model poin, so he echo signals of linear insecs curren movemens will be obained afer combining he echo signals of each model poin. As he body srucure and he node number boh have a grea difference in differen linear insecs, he analysis of each node will cause a redundancy of sysem model, which is no beneficial o he consrucion and simulaion of sysem model. Therefore, considering he movemen characerisics of model poins in normalized area a he same ime are in unison, he model poins wih a similariy in srucure and funcion can be normalized when building he model. L M- 1 M N- 2 N- 1 N Node1 Node m Node n Figure 1. N secions sysem model of linear insecs 2.2 Micro-Doppler echo wave equaions of model poins. In his paper, he linear insecs are divided ino muliple model poins, so we need o analyze he movemen characerisics of model poins firs before analyzing he movemen 216 Copyrigh c 2014 SERSC

3 forms. Movemens of Model poins in space conain vibraion, which he linear insecs model poins mainly own, and roaion. In his sudy, only he vibraion mode of model poins is analyzed. Figure 2 shows he posiion of Micro-Doppler radar Q and insec model poin P, which moves in regard o cenre O wih a insananeous disance D, an angle o he cenre radar and a direcion angle. The coordinae of model poin P a ime in plane-coordinae sysem is ( R 0 cos D cos, R0 sin D sin )[9, 10]. So he disance from model poin o he deecion radar can be expressed as: cos cos sin sin R R R D R D (1) Y D P Â o R R0 Q Á X Figure 2. Geomeric diagram of model poin and radar As he insananeous vibraion displacemen D of model poin is far more less han real deecion disance R 0, so he disance can be simplified o: 2 2 R R0 D 2 R0D (cos cos sin sin ) R0 D(cos cos sin sin ) (2) As he radar anenna paern used in his sysem is wide, he linear insecs which have relaive shor bodies can be seen as parallel beam. ha is o say, he angle beween movemen cenre O and radar direcion 0, he insananeous disance from model poin o radar can be expressed as: R R D 2R D cos R D cos (3) According o he linear insecs moion characerisics, he moion characerisics of model poins can be seen as low frequency signals of cycle vibraion under paricular movemen forms of linear insecs. So he vibraion equaions of model poins can be expressed wih Fourier series. As he vibraion frequency of linear insec model poin is low, we express i wih DC componen and fundamenal wave in Fourier series wih an ignorance of he high frequency componens [11]. So he insananeous displacemen of model poins can be expressed as: D A A 0 1cos(x* ) 1 B sin(x* ) (4) Where A 0 is he DC componen of Fourier series, A 1 and B 1 are fundamenal facors, is fundamenal frequency. So he disance from model poin P o radar Q is: R() R R A Acos(* ) Bsin(* ) (5) 12 Copyrigh c 2014 SERSC 217

4 The general ype of deecion radar s launch signal is S ( ) cos(2 f0),in which f 0 is he frequency of carrier frequency signal. The refleced wave signal of arge body radar received is: 4 cos( * ) B sin( * ) R0 A0 A1 1 Sr( ) Acos 20 f Where is he signal wavelengh. From equaion(6) we can see a high-frequency componen f 0 is included in he radar echo signal, he acquisiion and analysis of echo signals canno be done direcly by daa acquisiion sysem. This paper mixes he radar echo signals and launch signals wih frequency mixer, equaion (7) describes he mixed signals: A 4 R0 A 0 A 1cos( * ) 1 B sin( * ) Sr( )S () cos f0 4 2 A 4 R A A cos( * ) B sin( * ) cos Then he baseband signal can be obained by low-pass filer. A 4 R0 A0 A1cos( * ) 1 B sin( * ) Dr( ) cos 2 Which can be expressed wih plural form as: 4 cos( * ) B sin( * ) A R0 A0 A1 1 SD( ) exp j Esablishing he radar echo model of linear insecs (6) (7) (8) (9) As elecromagneic scaering calculaion of he linear insecs is very complicaed, in his paper, he linear insec body is divided ino muliple model poins according o is srucure. The moion equaions under differen movemen forms can be drawn near wih firs-order Fourier. The linear insecs' general movemen form echo model consruced by Doppler echo wave equaions of model poins can be expressed as: N N A 4 R0 A0 k A1 k cos( * k ) B1 k sin( * k ) Soal SDk ( ) exp j k1 2 k1, k 1,2,3 N (10) 3. The Radar Echo Model of Tenebrio Molior Movemens 3.1 The body movemen forms of enebrio molior The growh cycle of enebrio molior, a kind of common linear insec, is divided ino four periods as egg, larva, pupa and adul. In he larva period, body of enebrio molior is a linear form wih 14 secions and a lengh of 35 ~ 38m, he body join disribuion is apparen and he moion rule is relaively single [12, 13]. This paper builds he echo signal model wih he enebrio molior in larva period being he deecion arge. As we know, he link in head and ail in is movemen process are inensive, and he movemen forms of he wo pars are basically he same. So when building he moion model, i can be considered o be an 218 Copyrigh c 2014 SERSC

5 independen model and a mehod of combining some model poins can be adoped because he moion relaionship in body is ighness during he movemen. Figure 3 shows he disribuion of model poins of enebrio molior. Figure 3. The disribuion diagram of model poins of enebrio molior The moion process of enebrio molior manifess a moion of differen frequencies and ampliude of model poins. The frequency and ampliude of radar echo of each model poin is relaed o he ampliude and frequency of vibraion in he specific movemens of insecs, which can be measured by acual observaion and saisics. 3.2 The model poin parameers of enebrio molior Figure 4. Model poin daa of genly moving Figure 5. Model poin daa of swinging head Copyrigh c 2014 SERSC 219

6 Figure 6. Model poin daa of creeping up and down The parameers of model poin s vibraion characerisics can be obained by he observaion and saisics of experimenal samples. In his paper, Legria Hf R46, a high definiion camera, is used o record he movemens of enebrio molior, which are divided ino 3 caegories according o he movemen forms in an hour. Afer making a saisics of vibraion characerisics of each model poin in each movemen form, he vibraion ampliude are fied, as shown in figures above. Figure 4 shows he vibraion ampliude of each model poin in genle moving, from which we can see he ampliude is low and he vibraion frequency of each model poin, wih a cerain fundamenal frequency, changes in a small range. We can see from Figure 5 ha he vibraion ampliude of enebrio molior in swinging head is general high and he vibraion fundamenal frequency is lower han genle moving. Figure 6 shows he vibraion characerisics of enebrio molior in creeping up and down, from which we can see ha he vibraion ampliude is low bu he fundamenal frequency is high. Then we do a firs-order Fourier approaching o he daa wih CFTool in MATLAB, Table 1 shows he resuls. Table 1. The movemen parameers of each model poin in differen movemen forms of enebrio molior Move Sae Model Poin Genly moving Swinging head Creeping up and down A A 0 1 B1 A A 0 1 B1 A A 0 1 model poin model poin model poin model poin model poin The body movemen forms simulaion of enebrio molior The radar echo equaions in differen movemen forms of enebrio molior are buil based on he movemen model parameers of each model poin which is combined wih he insecs radar echo model. Figure 7-Figure 9 shows he ime-frequency diagrams of body echo obained by simulaing he echo model in differen movemen forms of enebrio molior wih ime-frequency analysis ools in MATLAB. From Figure 7 we can see ha he insec moion is relaively slow in genle moving, he energy specrum of echo is low and he frequency is relaively sable wih a cerain fundamenal frequency componen. Figure 8 shows he radar echo in swinging head, from which we can see ha he echo energy is high wih a lower B1 220 Copyrigh c 2014 SERSC

7 fundamenal frequency han genle moving, and he frequency changes wih a cerain regulariy. Figure 9 shows ha of creeping up and down, from which some high-frequency componens can be seen apparenly, which, wih higher fundamenal frequency componen han he oher wo movemen forms, can be disinguished. Figure 7. Simulaion daa of genly moving Figure 8. Simulaion daa of swinging head Figure 9. Simulaion daa of creeping up and down 4. Micro-Doppler Radar Deecion of Linear Insecs 4.1 Consrucion of sysem plaform Doppler deecion plaform mainly realizes he launching and receiving of microwave radar signals and he exracing and soring of Doppler signals. The sysem consiss of Doppler radar module, ADC, DSP, upper compuer daa sorage and display uni [14, 15], as is shown in Figure 10. Copyrigh c 2014 SERSC 221

8 Mealworms Inernaional Journal of Conrol and Auomaion T PD Doppler Radar Module PA VCO Se Frequency DSP R THP LAN LPF IFA SQL Server THP Display DSP ADC Figure 10. Doppler deecion plaform sysem consrucion Doppler radar module is mainly designed o accomplish generaing he signal wih GHz cenre frequency and 20dBm power, receiving he -95dBm signal and exracing Doppler signal. The sysem signal source can be generaed by VCO, and he frequency can be conrolled by upper compuer.some of he generaed radio frequency signals, afer power amplified by PA, are radiaed o deecion space by RF anenna, while he oher are received by mixer. The received signals ener LAN hrough receiving anenna and he amplified signals ener he mixer o ge he Doppler signal by mixing wih local oscillaor, which is now sill mixed wih high frequency componens, so he baseband signals need o be oupu afer low-pass filer. The baseband signals can carry he Doppler signal of insec movemen characerisics. As he ampliude of which is analog quaniy and small, need o be filered, amplified, urned ino digial signals by ADC and hen sen o he compuer by cenral processing uni. In he compuer, he signals will be processed and displayed and he local sorage of daa will be realized by SQL Server 2000 [16]. 4.2 Deecion mehod of enebrio molior s movemen forms The body of enebrio molior, wih flexibiliy and no regulariy in moions, is a very complex radar arge and hard o conrol. In he experimen, we adop a mehod of recording he insec movemen forms by cameras and a synchronized radar daa acquisiion plaform. A he end of he experimen, he imesamps of he enebrio molior in differen movemen forms will be found by he cameras, according o which, he Doppler echo daa informaion corresponding o he movemen forms can be found. The Doppler informaion of insecs is mainly found a he frequency of moion and he energy he echo brings, so he echo daa need o be STFT processed before being analyzed o obain he ime-frequency diagrams of Doppler echo and prominen he frequency and energy disribuion he echo signals include, which will hen be compared wih he simulaion daa [17]. 4.3 Daa analysis of enebrio molior s movemen forms Figure 11 and Figure 12 show he daa waveforms of enebrio molior in a period of genle moving and he ime-frequency diagram of Doppler signal, and we can see ha he energy of Doppler signal in genly moving of linear insecs is low and here is no sharp change of frequency. The Doppler frequency generaed is mosly from he Doppler frequency generaed by parallel ranslaion of enebrio molior and he noise of he sysem, which is in accordance wih he model buil above. Figure 13 and Figure 14 show he radar echo daa and Doppler signal frequency specrum in swinging head of enebrio molior, from which we can see a high echo energy and a low fundamenal frequency, which are also shown in he simulaion daa. 222 Copyrigh c 2014 SERSC

9 Figure 15 and Figure 16 show he radar echo daa and Doppler signal frequency specrum in creeping up and down of he enebrio molior, from which we can see a relaively high echo energy and fundamenal frequency including many high frequency componens. These componens can be well idenified, so we can see ha he real daa characerisic conforms o he model daa. This paper makes a comparison on simulaion and experimenal daa of Doppler echo of enebrio molior under differen moion morphology, and i is found ha he following hree aspecs of daa characerisics can be uilized o disinguish differen moion morphology of enebrio molior. 1) The body reflecing surface of enebrio molior deermines he densiy of energy specrum of Doppler echo. Mos of Doppler echoes generaed when he enebrio molior genly moves derive from he oscillaion of enebrio molior on model poin in he verical radar radial direcion, and mos of movemen processes of enebrio molior are horizonal movemen along body direcion; herefore, only few movemens are mapped on model poin in he radar radial direcion, which resuls in low densiy of energy specrum of radar echo. When enebrio molior swings is head and creeps up and down, he radar reflecing surface is whole body swaying, hus here is a high densiy of energy specrum of is echo. 2) The fundamenal frequency of Doppler echo signal reflecs main echo frequency of oscillaion a model poin of enebrio molior. I can be seen from he echo ime-frequency specrum diagram ha: when enebrio molior creeps up and down, here is a high frequency of oscillaion a each model poin of is body; his is refleced on large fundamenal frequency of Doppler echo signal. Meanwhile, i can be seen from he simulaed ime-frequency specrum diagram when he enebrio molior swings is head ha: he fundamenal frequency has cerain rule; however, in he experimen process, due o complicaed environmenal condiion, he rule of fundamenal frequency is no obvious, bu he overall frequency is relaively sable. 3) When he enebrio molior moves genly or swings is head, he Doppler echo frequency of is body is relaively sable, and boh he simulaion daa and acually-measured daa verify his characerisic. When he enebrio molior creeps up and down, he oscillaion phase and frequency of is body model is differen, which resuls in complicaed echo frequency; his is refleced on large flucuaion of fundamenal frequency in ime-frequency specrum. Boh experimenal and simulaion daa show ha differen moion morphology of enebrio molior can be well disinguished according o ime-frequency characerisics and densiy of energy specrum of Doppler echo of linear insecs. Figure 11. Doppler waveform of genly moving Copyrigh c 2014 SERSC 223

10 Figure 12. Time-frequency diagram of echo in genly moving Figure 13. Doppler waveform of swinging head Figure 14. Time-frequency diagram of echo in swinging head Figure 15. Doppler waveform of creeping up and down 224 Copyrigh c 2014 SERSC

11 Figure 16. Time-frequency diagram of echo in creeping up and down 5. Conclusion 1) In his paper, he echo model of linear insecs movemens is buil based on Micro-Doppler radar heory and Doppler echo vibraion equaions of poin arges. Also he echo waveforms of enebrio molior in differen movemen forms are obained by Micro-Doppler signal real-ime daa acquisiion sysem. The radar echo characerisics of linear insecs in differen movemen forms can be ruly refleced by he echo model of linear insecs movemens buil wih Micro-Doppler echo of model poins, which is obained by comparing he experimenal daa wih he simulaion resuls of movemen model. Using his mehod, microwave radar echo model of differen insecs in differen moion forms can be buil. The sudying of movemen characerisics which is achieved by analyzing echo daa can guide he developmen of bionic-robo in he fuure. 2) High-definiion cameras and Micro-Doppler radar are used in his paper o synchronously record he movemen forms of linear insecs. The resuls show an apparen difference of radar echo ime-frequency diagrams in differen movemen forms, which proves he feasibiliy of deecing he insecs movemen forms wih Micro-Doppler radar effec. They also prove ha i is feasible o deec he moion forms of hidden insecs by Micro-Doppler radar and differen moion forms in differen imes can promoe he sudying of heir movemen rules and life habis. 3) This paper also proves he feasibiliy of deecing he exisence of hidden insec pess by Micro-Doppler radar, so i becomes more argeed and scienific o preven and rea he hidden insec pess. 4) However, he Doppler radar deecion also has some deficiencies. Is foundaion refers o a variey of science. The simulaion daa will be differen from he real movemens if he model is buil only wih model poins. Muli-componen signal deecion is also a big difficuly as he Micro-Doppler signals of every insec moion are difficul o be isolaed accuraely. This paper is a preliminary aemp wih a follow-up sudy, and some more sophisicaed Micro-Doppler synhesis algorihm and es daa will be combined ogeher o furher improve he model. Acknowledgemens Thanks for he providing of he enebrio molior samples in his sudy from College of Resources and Environmen, Shandong Agriculural Universiy and he revising of his aricle by Qing wei Han and Cheng Yong Xiang from Sae Key Laboraory of Mechanical Engineering and Conrolling, Beijing Insiue of Technology. Copyrigh c 2014 SERSC 225

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