外文翻譯---基于arm與線性ccd的高速數據采集系統(tǒng)

1、<p><b>　　本科生外文文獻翻譯</b></p><p>　　外文題目：High–Speed Data Acquisition System Based on ARM & Linear-CCD</p><p>　　中文題目：基于ARM與線性CCD的高速數據采集系統(tǒng)</p><p>　　學 部 信息科學與工程

2、學部 </p><p>　　學科門類 工學 </p><p>　　專 業(yè) 電子信息工程 </p><p>　　學 號 2008480236 </p><p>　　姓 名 倪啟蒙 </p><p>　　指導教師 王蘭勛 </p>

3、;<p>　　High–Speed Data Acquisition System Based on ARM & Linear-CCD</p><p>　　Abstract : This paper presents a high speed acquisition system of linear-CCD based on ARM, high-speed linear-CCD and hi

4、gh-speed ADC are selected. As the sampling speed of A/D is slower than the working clock frequency of ARM, CPLD and FIFO are used as I/O between A/D and ARM. It makes the circuit works harmonious, simple and easy control

5、ling, and also increases the efficiency of ARM. In order to increase the communication speed, the Universal Serial Bus (USB) technology is adopted to communicate</p><p>　　I. Introduction </p><p>

6、;　　In electrification railways, in order to extend the life of the pantograph on electric locomotives, so that the slider of pantograph wear evenly, the contact-line (electrified railway power feed line) in straight-line

7、 segments is arranged as zigzag route (curve section arranged in the form of polyline). The distance between the contact-line of positioning point and the pantograph centerline track is called out stagger-value, which is

8、 a key indicator of contact-line .</p><p>　　Stagger-value can not be ignored, the value too small will affect the slider of pantograph wear evenly and the purpose of extending using life; otherwise, in some

9、cases (such as caught in a stiff winds), cause a large range of lateral movement of the roof (and the higher the speed, the greater pantograph swing around), some parts of contact-line will be in excess of the effective

10、work length of pantograph, so that the stagger-value of contact-line beyond the standard range, leading to deteriorat</p><p>　　II. System Components </p><p>　　System hardware components are show

11、n in figure 1. </p><p>　　The system consists of the following components: (1) using TOSHIBA Company’s high-speed linear array CCD to achieve the digitization of contact-line images (CCD output the signal of

12、corresponding time sequence of position); (2) using Atmel Company’s AT91RM9200 processor of ARM9 series to realize digital signal acquisition and processing; (3) using PDIUSBD12 USB interface device to complete the data

13、communications between measurement system and the PC. </p><p>　　Due to the characteristics of its improved Harvard structure, special instructions and quick to realize a variety of signal processing, ARM pr

14、ocessor is widely used in image processing, communications, radar, sonar, precision machinery fields, etc. ARM processor is adopted for its arithmetic speed and bus width. As the real-time signal analysis and calculation

15、 require a high speed of computing, Atmel Company’s ARM chip—AT91RM9200 is selected. The chip is ARM920T based, high-performance, low pow</p><p>　　Fig 1 System block diagram</p><p>　　III. Real-t

16、ime processing and transmission of CCD digital image </p><p>　　In order to achieve real-time digital image </p><p>　　transmission, several major factors which affect real-time transmission shoul

17、d be necessary to solve: First, the speed of linear array CCD data acquisition; Second, the transmission speed between linear array CCD and ARM processor; the third is the data transmission speed between ARM processor an

18、d computer. The following will be described in detail. </p><p>　　A. Linear array CCD acquisition speed </p><p>　　Acquisition speed is a critical performance indicator for image sensor, TOSHIBA C

19、ompany’s TCD1209D linear array CCD is used to meet the targets. Its clock pulse frequency can operate as high as 20MHz, especially suitable for high-speed conditions of size measurement and dynamic analysis.</p>&

20、lt;p>　　Fig 2 Linear CCD TCD1209D and its time sequence diagram</p><p>　　Linear array CCD TCD1209D and its time sequence diagram are shown in figure 2. </p><p>　　B.Transmission speed between C

21、CD and ARM processor </p><p>　　In order to improve the speed of CCD data acquisition and reduce conversion time, adopting high speed A/D converter can make it exchange data with ARM processor at high-speed.

22、ADC08200, Analog Company's nanosecond conversion device is adopted. It’s a single-channel, 8-bit A/D converter, which operates over a wide range of temperature, converts fast, operates at conversion rates up to 230 M

23、SPS, thus achieving entire signal acquisition of linear array CCD. ADC08200 is shown in figure 3.</p><p>　　Fig 3 High-speed A/D converter ADC080200</p><p>　　FIFO is used as a data buffer to co-o

24、rdinate the rate of ARM processor and ADC. It is a two-port (input and output port) memory for temporary storage of first in first out data. Due to the time to write data to FIFO is far less than the A/D conversion time,

25、 therefore, the acquisition speed depends on the A/D conversion speed. </p><p>　　In order to improve the speed of the entire measurement system, the time sequence of entire circuit is precisely controlled by

26、 the CPLD to make the circuit works harmonious. CCD driving signal, integration time control, address decoding, A/D conversion control, data buffer and data acquisition logic functions integrate in the CPLD, so that the

27、entire circuit structure is simple and reliable. </p><p>　　In order to further enhance the system speed, when the system starts, system programs are transferred to high-speed SRAM for running and SDRAM for d

28、ata storage; SRAM, SDRAM should be placed as close as possible to ARM processors, and the signal lines the shortest possible. </p><p>　　ARM processor (AT91RM9200), the signal processing core of the entire ha

29、rdware system, read the CCD light intensity signal from FIFO, calculate the distribution of contact-line image in the CCD with corresponding algorithm, and transfer the result to the slave computer through USB. </p>

30、;<p>　　C. Transmission speed between ARM processor and computer </p><p>　　In order to increase the speed of data transmission and reduce transmission delay, USB interface is used for data transmission

31、. USB1.1 interface support low-speed and full-speed transmission, data transfer rates has reached 1.5Mbps in low-speed mode, the transmission speed up to 12Mbps in full speed mode. Philips Company’s PDIUSBD12 is adopted.

32、 </p><p>　　When a USB device inserted into the PC, PC enumerates USB device automatically. When detecting equipment to insert, PC send query request. USB devices respond to the request and send equipment Ven

33、dor ID and Product ID; PC loads the corresponding device driver with these two ID to complete the enumeration process. </p><p>　　PC-side USB device driver is completed by WinDriver. Data communication betwee

34、n PC and USB equipment mainly includes two aspects: first, read the sample data; second, send control commands to the acquisition system. </p><p>　　IV. CCD image recognition algorithm </p><p>　　

35、ARM processor is mainly responsible for the solution of stagger-value; it’s the process of image identification, including background separation and feature extraction of the image data. Identification of the image is fo

36、r image gray only; the standard deviation threshold tracking method is adopted. The image is composed of black-and-white texture, and gray-scale varies greatly, with a larger standard deviation; and background gray distr

37、ibution is relatively flat, with small standard deviation. T</p><p>　　This system not only measures the contact-line instant position, but also calculates the abrasion state of the contact-line to evaluate i

38、ts life span. System support by associated PC software, through subsequent playback of the data collected, to check the situation of stagger-value, as well as the abrasion of contact-line, and decide whether to adjust an

39、d replace or not</p><p>　　V. Measures of improving system reliability </p><p>　　High-speed data acquisition system is inevitably affected by interference from the external environment. As the co

40、mplex environment around the measurement system, many factors interfere with the system. Electromagnetic interference around 27.5KV high-voltage catenary affects great; the pantograph detaching will be accompanied by the

41、 emergence of arc sparks, this phenomenon interfere with communication line along the lines, accompanied by high-frequency electromagnetic waves, therefore, necessary</p><p>　　基于ARM與線性CCD的高速數據采集系統(tǒng)</p>

42、<p>　　摘要：本文介紹了一個基于ARM的線性CCD高速采集系統(tǒng)，系統(tǒng)中選擇了高速線性CCD和高速ADC。因為ADC的采樣速度相對ARM的工作時鐘頻率較慢，所以使用CPLD和FIFO作為A/D和ARM之間的I/O接口。它使電路工作在更加平穩(wěn)、簡潔而易于控制，同時也提高了ARM的工作效率。為了提高通信速度，這里采用通用串行總線（USB）技術來與PC進行通信。 ARM是用來控制主處理器的數據采集，數據的計算和數據傳輸。結果證明

43、，整個系統(tǒng)能高效運作。該系統(tǒng)可應用于高速數據采集及多路模擬信號的工作環(huán)境下。</p><p><b>　　1 引言</b></p><p>　　在電氣化鐵路，為了擴大對電力機車受電弓的壽命，所以要使受電弓滑塊磨損均勻，接觸線的直線段（電氣化鐵路供電線）排列為曲折路線（彎段被安排成折線的形式）。之間的接觸線的定位點和受電弓軌道中心線距離稱為錯開值，這是一種接觸線的關鍵

44、指標。</p><p>　　錯開值是不可忽視的，這個值過小會影響到受電弓滑塊磨損的均勻性，從而影響到延長使用壽命的目的，然而，在某些情況下（比如陷入了激烈的風中），造成大范圍的在屋部的橫向運動（并且速度越快，受電弓的左右擺動越劇烈），接觸線將在某些部分將會超過受電弓的有效工作長度，從而使錯開，接觸線值超出標準范圍的錯開值，導致了當前連接的破壞，甚至導致了會產生受電弓事故的錯誤運行。受電弓與滑觸線發(fā)生故障，將導致列

45、車正常運行的中斷，從而對鐵路運輸產生嚴重的影響。為了避免這些情況，錯開值及其變化應經常性地予以測試。因此，一個機車的接觸線式在線監(jiān)測系統(tǒng)，及與其配套的數據采集系統(tǒng)被開發(fā)出來，它的工作是實時地、迅速地計算錯開值。</p><p><b>　　2 系統(tǒng)組件</b></p><p>　　系統(tǒng)硬件組成如圖1所示。</p><p>　　該系統(tǒng)由下列部分

46、組成：（1）采用東芝公司的高速線陣CCD實現接觸線影像的數字化（CCD輸出對應的時間序列位置的信號），（2）采用Atmel公司ARM9系列處理器中的AT91RM9200，實現了數字信號的采集和處理；（3）采用PDIUSBD12的USB接口設備，完成測量系統(tǒng)與PC機之間的數據通訊。</p><p>　　由于它改進型的哈佛結構，特殊的指令系統(tǒng)以及迅速實現各種信號處理的特點，ARM處理器被廣泛應用于圖像處理，通信，雷達

47、，聲納，精密機械等領域。ARM處理器正因其算術速度和總線寬度而被采用。隨著實時信號分析和計算都需要很快運算速度，所以系統(tǒng)選擇了ATMEL公司的ARM芯片AT91RM9200。該芯片是基于ARM920T的，高性能，低功耗的16/32位RISC（精簡指令集計算機）微控制器，它集成了一套豐富的外圍設備的應用，并在那些需要一大批外圍設備，并能在低功耗的外設和嚴格穩(wěn)定工作的工業(yè)控制應用中，提供了一個單芯片的解決方案。</p><

48、;p>　　圖1 系統(tǒng)硬件組成</p><p>　　3 CCD數字圖像的實時處理與傳輸</p><p>　　為了實現實時的數字圖像的傳輸，幾大影響實時傳輸的因素應該予以解決：第一，線陣CCD的數據采集速度；二是線陣CCD和ARM處理器之間的傳輸速度；第三是ARM處理器和計算機之間的數據傳輸速度。下面將給以詳細描述。</p><p>　　線陣CCD的采集速度&

49、lt;/p><p>　　采集速度對于圖像傳感器來說，是一個關鍵的性能指標，這里采用東芝公司的TCD1209D線陣CCD來滿足目標要求。它可工作在可高達20MHz的時鐘脈沖頻率下，所以對高速條件下的尺寸測量和動態(tài)分析特別適合。</p><p>　　圖2 TCD1209D及它的時序</p><p>　　線陣CCD TCD1209D，以及它的時序圖如圖2所示。</p&

50、gt;<p>　　B.CCD和ARM處理器之間的傳輸速度</p><p>　　為了提高CCD的數據采集速度，減少轉換時間，現使用高速A/D轉換器，以使它在高速環(huán)境下與ARM處理器進行數據交換。這里選擇ADC08200，Analog公司的一個納秒級轉換器。這是一個單通道，8位的A/D轉換器，它可以在一較寬的溫度范圍內工作，轉換速度快，工作時的轉換速率高達230 MSPS，從而實現整個線陣CCD的信號采

51、集。ADC08200如圖3所示。</p><p>　　圖3 ADC08200</p><p>　　FIFO用于作為數據緩沖區(qū)，協(xié)調了ARM處理器和ADC的速率。這是一個兩端口（輸入和輸出端口）的，臨時性存儲的，先入先出的數據存儲器。由于向FIFO中寫入數據的時間遠遠小于A/D轉換的時間，因此，數據采集的速度取決于A/D轉換的速度。</p><p>　　為了提高整個

52、測量系統(tǒng)的速率，整個電路的時序是由CPLD的精確控制，以使電路協(xié)調地工作。 CCD驅動信號，積分時間控制，地址譯碼，A/D轉換控制，數據緩沖和數據采集邏輯功能都集成在CPLD上，使得整個電路結構簡單，功能可靠。</p><p>　　為了進一步提高系統(tǒng)的速度，當系統(tǒng)啟動時，系統(tǒng)程序被傳送到高速SRAM去運行，并且使用高速SRAM來存儲數據；SRAM，SDRAM應盡量靠近ARM處理器放置，而信號線應盡可能地最短。&l

53、t;/p><p>　　ARM處理器（AT91RM9200）作為整個硬件系統(tǒng)的信號處理內核，需要讀取存儲在FIFO中的CCD光強信號，應用相應的算法計算CCD中接觸線圖像的分布，并通過USB把結果傳送給從屬計算機。</p><p>　　C.ARM處理器和計算機之間的傳輸速度</p><p>　　為了提高數據傳輸速度，減少傳輸延遲，USB接口用于數據傳輸。 USB1.1接口

54、支持低速和全速傳輸，數據傳輸速率在低速模式下已經達到了1.5Mbps，全速模式下傳輸速率可達12Mbps。這里采用飛利浦公司的PDIUSBD12。</p><p>　　當一個USB設備插入到PC，PC機會自動枚舉USB設備。當檢測設備插入時，電腦發(fā)送查詢請求。 USB設備便響應請求并發(fā)送設備供應商的ID和產品的ID；電腦根據這兩個ID加載相應的設備驅動程序以完成枚舉過程。</p><p>

55、　　PC端的USB設備驅動程序由WinDriver完成編寫。 PC與USB設備之間的數據通信主要包括兩個方面：首先，閱讀樣本數據；第二，發(fā)送控制命令到數據采集系統(tǒng)。</p><p>　　4 CCD圖像識別算法</p><p>　　ARM處理器主要負責錯開值的解決；這是個圖像識別的過程，包括背景的分離和圖像數據中特征的提取。圖像識別只在于圖像的灰度；這里采用標準差閾值法進行跟蹤。該圖像是由

56、黑色和白色紋理組成的，并且灰度變化較大，有很大的標準偏差；還有背景灰度分布較為平滑，有較小的標準偏差。因此，把每個點作為它那一組像素點的中心，計算出它的標準偏差，得出值超過一定的閾值的點確定為前臺點，或作為背景。</p><p>　　該系統(tǒng)不僅是測量接觸線的即時位置，還計算了接觸線的磨損程度，以評估它的使用壽命。通過隨后對采集到數據的回放，相關的PC軟件支持著系統(tǒng)來檢查錯開值的情況，以及接觸線磨損，并且決定是否予

57、以調整和更換。</p><p>　　5 提高系統(tǒng)可靠性的措施</p><p>　　高速數據采集系統(tǒng)會不可避免地受到外部環(huán)境的干擾。由于測量系統(tǒng)周圍復雜的環(huán)境，許多因素會干擾到系統(tǒng)。27.5KV的高壓滑觸線周圍的電磁干擾所產生的影響很大；受電弓的分離將帶來電弧火花，這種現象會干擾通訊線路沿線的高頻電磁波，因此，需要采取一些必要的抗干擾措施。為了提高抗干擾能力，這里采用的抗干擾措施如下：采取