毕业论文外文翻译基于ARM与线性CCD的高速数据采集系统.docx

1、毕业论文外文翻译基于ARM与线性CCD的高速数据采集系统 毕业设计中英文翻译 机电工程学院 学生姓名： 学号： 探测制导与控制技术学 院： 专 业： 指导教师： 2012年 6月HighSpeed Data Acquisition System Based on ARM & Linear-CCDDong Jianjun Zhao XiaojinDept. Four, The First Aeronautical Technical College of the Air Force Xinyang 464000.China.Abstract : This paper presents a hig

2、h speed acquisition system of linear-CCD based on ARM, high-speed linear-CCD and high-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 cont

3、rolling, and also increases the efficiency of ARM. In order to increase the communication speed, the Universal Serial Bus (USB) technology is adopted to communicate with the PC. ARM is the key processor utilized to control the data sampling, data compute and data transfer. As a result, the whole sys

4、tem works effective. The system can be applied to the high speed data acquisition and operation situations from multi-channel analog signals. Key Words : ARM; Linear CCD; Contact-line; Pantograph; Stagger value I. Introduction In electrification railways, in order to extend the life of the pantograp

5、h on electric locomotives, so that the slider of pantograph wear evenly, the contact-line (electrified railway power feed line) in straight-line 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 p

6、antograph centerline track is called out stagger-value, which is a key indicator of contact-line .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 cases (such as caught in a stiff winds)

7、, 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 work length of pantograph, so that the stagger-value of contact-line beyond the standard range, leading to deterioratio

8、n of the current collection, and even cause incorrect running of the pantograph accident. Pantograph-catenary malfunction will result in interruption of train operation, which impact on rail transport seriously. In order to avoid these phenomena, the stagger-value and its changes should be tested re

9、gularly.Therefore, a locomotive contact-line monitoring system and its mating data acquisition system were developed, which calculate the instant stagger-value quickly.II. System Components System hardware components are shown in figure 1. The system consists of the following components: (1) using T

10、OSHIBA Companys high-speed linear array CCD to achieve the digitization of contact-line images (CCD output the signal of corresponding time sequence of position); (2) using Atmel Companys AT91RM9200 processor of ARM9 series to realize digital signal acquisition and processing; (3) using PDIUSBD12 US

11、B interface device to complete the data communications between measurement system and the PC. Due to the characteristics of its improved Harvard structure, special instructions and quick to realize a variety of signal processing, ARM processor is widely used in image processing, communications, rada

12、r, sonar, precision machinery fields, etc. ARM processor is adopted for its arithmetic speed and bus width. As the real-time signal analysis and calculation require a high speed of computing, Atmel Companys ARM chipAT91RM9200 is selected. The chip is ARM920T based, high-performance, low power consum

13、ption 16/32-bit RISC(reduced instruction set computer) microcontroller, which incorporates a rich set of application peripherals and provide a single-chip solution for industrial control applications that require a wide range of peripherals at low power consumption and strictly stable working. Fig 1

14、 System block diagram. Real-time processing and transmission of CCD digital image In order to achieve real-time digital image transmission, several major factors which affect real-time transmission should be necessary to solve: First, the speed of linear array CCD data acquisition; Second, the trans

15、mission speed between linear array CCD and ARM processor; the third is the data transmission speed between ARM processor and computer. The following will be described in detail. A. Linear array CCD acquisition speed Acquisition speed is a critical performance indicator for image sensor, TOSHIBA Comp

16、anys 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.Fig 2 Linear CCD TCD1209D and its time sequence diagramLinear array CCD TCD1209D and its time seq

17、uence diagram are shown in figure 2. B.Transmission speed between CCD and ARM processor 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. ADC08200, Analog Companys nanosecond

18、 conversion device is adopted. Its 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 MSPS, thus achieving entire signal acquisition of linear array CCD. ADC08200 is shown in figure 3.Fig 3 High-speed A/D conv

19、erter ADC080200FIFO is used as a data buffer to co-ordinate 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, therefore, the acquisition

20、speed depends on the A/D conversion speed. In order to improve the speed of the entire measurement system, the time sequence of entire circuit is precisely controlled by the CPLD to make the circuit works harmonious. CCD driving signal, integration time control, address decoding, A/D conversion cont

21、rol, data buffer and data acquisition logic functions integrate in the CPLD, so that the entire circuit structure is simple and reliable. 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 data storage; S

22、RAM, SDRAM should be placed as close as possible to ARM processors, and the signal lines the shortest possible. ARM processor (AT91RM9200), the signal processing core of the entire hardware system, read the CCD light intensity signal from FIFO, calculate the distribution of contact-line image in the

23、 CCD with corresponding algorithm, and transfer the result to the slave computer through USB. C. Transmission speed between ARM processor and computer In order to increase the speed of data transmission and reduce transmission delay, USB interface is used for data transmission. USB1.1 interface supp

24、ort 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 Companys PDIUSBD12 is adopted. When a USB device inserted into the PC, PC enumerates USB device automatically. When detecting equipmen

25、t to insert, PC send query request. USB devices respond to the request and send equipment Vendor ID and Product ID; PC loads the corresponding device driver with these two ID to complete the enumeration process. PC-side USB device driver is completed by WinDriver. Data communication between PC and U

26、SB equipment mainly includes two aspects: first, read the sample data; second, send control commands to the acquisition system. IV. CCD image recognition algorithm ARM processor is mainly responsible for the solution of stagger-value; its the process of image identification, including background sep

27、aration and feature extraction of the image data. Identification of the image is for 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 di

28、stribution is relatively flat, with small standard deviation. Therefore, the standard deviation of each point as the center of a group of pixels is calculated, the value greater than a certain threshold determine the point in the foreground, or as the background. This system not only measures the co

29、ntact-line instant position, but also calculates the abrasion state of the contact-line to evaluate its 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

30、 whether to adjust and replace or notV. Measures of improving system reliability High-speed data acquisition system is inevitably affected by interference from the external environment. As the complex environment around the measurement system, many factors interfere with the system. Electromagnetic

31、interference around 27.5KV high-voltage catenary affects great; the pantograph detaching will be accompanied by the emergence of arc sparks, this phenomenon interfere with communication line along the lines, accompanied by high-frequency electromagnetic waves, therefore, necessary anti-interference

32、measures should be taken.In order to improve the ability of anti-interference, anti-jamming measures taken are as follows: take anti-interference design of PCB circuit to reduce the external interference on system; all cables adopt shielded cable with wave-proof sleeve; equipment shell adopts shielding material and detection window of the shell use gauze to isolate the interference. VI. Results We have used this highspeed data acquisition system in Wuhan south locomotive-depot to measure the contact-line instant position, and the test result shows that the whole