岳 晗,裴東興,張 瑜,馬鐵華
(1.中北大學(xué)儀器科學(xué)與動(dòng)態(tài)測試教育部重點(diǎn)實(shí)驗(yàn)室,山西太原 030051;2.中北大學(xué)電子測試技術(shù)重點(diǎn)實(shí)驗(yàn)室,山西太原 030051)
彈丸轉(zhuǎn)速-炮口速度無線彈載測試系統(tǒng)設(shè)計(jì)
岳 晗1,2,裴東興1,2,張 瑜1,2,馬鐵華1,2
(1.中北大學(xué)儀器科學(xué)與動(dòng)態(tài)測試教育部重點(diǎn)實(shí)驗(yàn)室,山西太原 030051;2.中北大學(xué)電子測試技術(shù)重點(diǎn)實(shí)驗(yàn)室,山西太原 030051)
針對(duì)現(xiàn)有存儲(chǔ)測試系統(tǒng)的通信方式存在通信設(shè)備位置固定、操作不便和數(shù)據(jù)傳輸可靠性差的問題,設(shè)計(jì)了彈丸轉(zhuǎn)速-炮口速度無線彈載測試系統(tǒng)。該系統(tǒng)以CC430作為主控芯片,將單片機(jī)與無線射頻模塊集成于一體,提高了系統(tǒng)的集成度,選擇天線并設(shè)計(jì)天線匹配電路以實(shí)現(xiàn)數(shù)據(jù)的無線收發(fā)功能。利用地磁線圈切割磁感線產(chǎn)生感應(yīng)電動(dòng)勢來計(jì)算彈丸轉(zhuǎn)速,并依據(jù)轉(zhuǎn)速、纏度可求出彈丸在炮口的初速。經(jīng)實(shí)彈測試驗(yàn)證,該系統(tǒng)在433MHz頻段工作,通信速率可達(dá)250kbps,在200m以內(nèi)能夠?qū)崿F(xiàn)完整的數(shù)據(jù)收發(fā),能夠準(zhǔn)確測量彈丸的轉(zhuǎn)速及炮口速度,其炮口速度測量誤差在±1.2%以內(nèi)。
存儲(chǔ)測試;CC430;無線射頻;轉(zhuǎn)速;炮口速度
彈丸的轉(zhuǎn)速和炮口速度是影響火炮威力及射擊精度的重要參量,炮口速度是決定外彈道三個(gè)基本參數(shù)(彈道系數(shù)、射角和初速)之一?,F(xiàn)有的炮口初速測量方法有紅外遙測法和雷達(dá)測速法等,它們都屬于外測法,受外界因素影響大、測試難度大。針對(duì)彈載測試的特殊性,設(shè)計(jì)了基于CC430的彈載測試系統(tǒng),其具有誤差不隨時(shí)間積累、測試精度高、數(shù)據(jù)傳輸準(zhǔn)確和方便等優(yōu)點(diǎn)。
其測試裝置置于彈丸內(nèi)部,能夠測量彈丸的轉(zhuǎn)速及炮口速度,并將測量數(shù)據(jù)通過無線射頻方便準(zhǔn)確地上傳至計(jì)算機(jī)。
1.1 系統(tǒng)架構(gòu)
基于CC430的無線彈載測試系統(tǒng)主要由薄膜線圈式地磁傳感器、信號(hào)調(diào)理電路和CC430單片機(jī)組成。測試系統(tǒng)的原理框圖如圖1所示。
1.2 硬件電路
設(shè)計(jì)采用自制的薄膜線圈式地磁傳感器,利用先進(jìn)的薄膜加工工藝,設(shè)計(jì)制造成柔性的多層薄膜線圈。該傳感器可靈活地粘貼于測試裝置的表面,極大地提高了傳感器的靈活性、可靠性和安裝適應(yīng)性[]。
測試中采用CC430F6137作為主控芯片,運(yùn)用其內(nèi)部自帶的12bit的AD轉(zhuǎn)換器,將從傳感器輸出的模擬信號(hào)轉(zhuǎn)換成數(shù)字信號(hào)。CC430的最大特點(diǎn)就是集成了RF1A無線射頻模塊,極大地方便了數(shù)據(jù)的傳輸[2-4]。對(duì)無線模塊的天線電路進(jìn)行相關(guān)的無線匹配網(wǎng)絡(luò)設(shè)計(jì)(平衡轉(zhuǎn)換和阻抗匹配)即可實(shí)現(xiàn)數(shù)據(jù)的無線收發(fā)。設(shè)計(jì)中采用433MHz頻段。選用SMA接頭的全向天線,天線阻抗為50 Ω,只要設(shè)計(jì)相應(yīng)的天線匹配電路[5],即可實(shí)現(xiàn)無線收發(fā)功能。運(yùn)用軟件AppCAD對(duì)到SMA天線座之間的微帶線進(jìn)行了線寬和銅厚設(shè)計(jì)[6],其線寬為1.81mm,銅厚為0.035mm,經(jīng)過調(diào)試,其通信速率可達(dá)250kbps,在200m以內(nèi)可以準(zhǔn)確地實(shí)現(xiàn)數(shù)據(jù)的收發(fā)功能。從而精確、方便地實(shí)現(xiàn)了測試系統(tǒng)與上位機(jī)間的數(shù)據(jù)傳輸。
筆者采用薄膜線圈式地磁傳感器直接測量彈丸轉(zhuǎn)速。利用薄膜線圈式地磁傳感器在子彈拋撒時(shí),切割地磁場磁力線,由于子彈在空中做翻轉(zhuǎn)運(yùn)動(dòng),使得通過薄膜式地磁傳感器的磁通量發(fā)生變化,根據(jù)電磁感應(yīng)定律可得到隨磁通量變化的感應(yīng)電動(dòng)勢。測試裝置在彈上的安裝方式如圖2所示。一個(gè)N匝線圈的閉合電路,切割地磁場產(chǎn)生感應(yīng)電動(dòng)勢為[7-8]
式中:E為線圈中產(chǎn)生的感應(yīng)電動(dòng)勢;Φ為線圈磁通量(單匝);t為時(shí)間;N為線圈匝數(shù);B為當(dāng)?shù)氐卮艌隹偞鸥袘?yīng)強(qiáng)度;B為總磁感應(yīng)強(qiáng)度矢量;S為線圈面積;S為面積矢量;θ為線圈旋轉(zhuǎn)角;為線圈轉(zhuǎn)動(dòng)的角速度ω。
由上述推導(dǎo)可知,當(dāng)彈丸高速自旋時(shí),線圈輸出感應(yīng)電動(dòng)勢信號(hào)E為周期性的正弦信號(hào),正弦信號(hào)的頻率代表地磁線圈傳感器的轉(zhuǎn)動(dòng)頻率。
通過彈丸角速度ω的測量可以計(jì)算出彈丸出炮口時(shí)的速度值,利用下式計(jì)算。
式中:v0為彈丸出炮口時(shí)的速度值;ηg為火炮膛線纏度;ω0為彈丸出炮口時(shí)的轉(zhuǎn)動(dòng)角速度;D為彈丸直徑;rg為膛線的纏角。
分析上式可知,只要測量出彈丸的角速度即可求出彈丸出炮口時(shí)的速度。對(duì)于確定的火炮,其膛線纏度及口徑都是確定的。
設(shè)計(jì)中采用點(diǎn)對(duì)點(diǎn)的通信方式,即兩個(gè)子系統(tǒng)通信獨(dú)享一條線路[9]。該無線通信系統(tǒng)由發(fā)射板(置于被測現(xiàn)場)和接收板組成,二者間采用中斷來進(jìn)行發(fā)射和接收,用LED閃爍表示響應(yīng),其通信協(xié)議如圖3所示,圖3(a)為射頻發(fā)射流程,圖3(b)為射頻接收流程。
上述圖3通信協(xié)議在IAR軟件中調(diào)試,以驗(yàn)證其正確性。運(yùn)用SmartRF Studio軟件對(duì)CC430的RF寄存器的值進(jìn)行配置,可對(duì)RF參數(shù)進(jìn)行仿真。目前國內(nèi)使用較多的免費(fèi)頻段有433MHz和315MHz,由于315MHz使用較多,易受干擾,因此設(shè)計(jì)中采用433MHz。只需配置頻率、調(diào)制方式、功率和晶振頻率這幾項(xiàng),其他采用默認(rèn)配置,配置完成后生成.h的文件即可植入程序中使用。
按照上述的寄存器配置及收發(fā)流程,在IAR軟件中對(duì)電路進(jìn)行調(diào)試,經(jīng)調(diào)試在433MHz頻段,數(shù)據(jù)傳輸率為250kbps時(shí),可以準(zhǔn)確地實(shí)現(xiàn)數(shù)據(jù)收發(fā)。驗(yàn)證性試驗(yàn)如下所述:設(shè)置發(fā)送60字節(jié)的數(shù)據(jù),發(fā)送內(nèi)容為00H~3BH,即發(fā)送緩存TxBuffer中的數(shù)據(jù)為00H~3BH。接收到的數(shù)據(jù)存至接收緩存RxBuffer中,從調(diào)試界面中得到的數(shù)據(jù)也為00H~3BH,與發(fā)送的數(shù)據(jù)一致,同時(shí)在其末尾附加兩個(gè)狀態(tài)字節(jié),這些狀態(tài)字節(jié)包含了接收信號(hào)強(qiáng)度值、鏈路質(zhì)量指示值以及CRC校驗(yàn)值,說明該無線射頻模塊能夠?qū)崿F(xiàn)準(zhǔn)確的數(shù)據(jù)收發(fā)功能。
對(duì)155殺爆彈進(jìn)行實(shí)彈測試,利用射頻傳輸測得的數(shù)據(jù)得到彈丸在0~1s內(nèi)感應(yīng)電動(dòng)勢隨時(shí)間變化的曲線,如圖4所示。
為看清楚信號(hào)的變化情況,給出了彈丸在0~100ms內(nèi)感應(yīng)電動(dòng)勢隨時(shí)間變化的曲線,如圖5所示。從圖中可以看出,彈丸出炮口是在 時(shí)間為20 ms時(shí),計(jì)算出此時(shí)彈丸的角速度后依據(jù)式(2)可以求出彈丸出炮口時(shí)的速度。
依據(jù)圖5計(jì)算得到彈丸在炮口的轉(zhuǎn)速為18 077r/min,膛線的纏角與彈丸直徑D為確定值,根據(jù)式(2)計(jì)算得到彈丸炮口初速v0為919.3 m/s。為驗(yàn)證該方案的可行性,在實(shí)彈測試的同時(shí)運(yùn)用雷達(dá)直接測速法測量的彈丸炮口速度為930.2 m/s,可以算出其誤差為1.1%。經(jīng)過多次試驗(yàn)驗(yàn)證,其速度誤差值在±1.2%以內(nèi),滿足測量要求。
筆者設(shè)計(jì)了一種基于CC430的無線彈載測試系統(tǒng),該測試系統(tǒng)克服了全彈道測試難度大、煙霧區(qū)數(shù)據(jù)難以獲取的困難,運(yùn)用CC430上自帶的無線射頻模塊實(shí)現(xiàn)測試系統(tǒng)與上位機(jī)之間的通信,能夠準(zhǔn)確測量彈丸的轉(zhuǎn)速及炮口速度。經(jīng)過實(shí)彈測試驗(yàn)證,該測試系統(tǒng)可以準(zhǔn)確完整地傳輸數(shù)據(jù),極大地提高了操作系統(tǒng)的便捷性。
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Wireless Missile-borne Test System Design Based on Projectile Rotating Speed-muzzle Velocity
YUE Han1,2,PEI Dong-xing1,2,ZHANG Yu1,2,MA Tie-hua1,2
(1.Ministry of Education Key Laboratory of Instrumentation Science and Dynamic Measurement,North University of China,Taiyuan 030051,Shanxi,China;2.National Key Laboratory of Eletronic Measurement Technology,North University of China,Taiyuan 030051,Shanxi,China)
As regards the problems of stationary position of communication equipment,inconvenient operation and inferior reliability of data transmission existed in the communication ways of current storage test system,wireless missile-borne testing system based on projectile rotating speed-muzzle velocity was designed.The system made use of CC430as the main control chip,integrated the MCU and RF module into one chip,and thus improved the system integration degree.The antenna was chosen and the antenna matching circuit was designed so as to acquire the functions of wirelessly receiving and transmitting data.Projectile rotating speed was calculated by use of the geomagnetic coil cutting magnetic line to generate inductive electromotive force,and the projective muzzle velocity was calculated based on data of rotating speed and twist.The live ammunition test demonstrated that this system can operate at 433MHz and the communication rate can reach 250kbps,the system can achieve complete data reception and transmission within 200meters and the measuring results of projectile rotating speed and muzzle velocity are accurate,the measurement error of muzzle velocity in the system is within±1.2%.
storage test;CC430;radio frequency;rotating speed;muzzle velocity
TJ760.6
A
1673-6524(2014)01-0071-04
2013-05-08;
2013-09-02
岳晗(1988-),女,碩士研究生,主要從事動(dòng)態(tài)測試與智能儀器研究。E-mail:18734137263@163.com