外文翻譯車輛檢測技術(shù)在交通管理上的應(yīng)用

1、畢業(yè)設(shè)計(jì)(論文)外文資料翻譯院 系電氣學(xué)院專業(yè)電氣工程及其自動化學(xué)生姓名班級學(xué)號外文出處指導(dǎo)教師評語：指導(dǎo)教師簽名：年月日vehicle detector technologies for traffic management applicationspart 1lawrence a. klein consultant ten different detector technologies were recently evaluated as part of the fhwa-sponsored detection technology for ivhs program. the two pr

2、imary goals of the program were: 1. to determine traffic parameters and their corresponding measurement accuracies for future intelligent transportation systems (its) applications, 2. to perform laboratory and field tests with above-the-road mounted, surface, and subsurface detectors to determine th

3、eir performance.detectors representative of all tested technologies were found to satisfy current traffic management requirements. however, improved accuracies and new types of information, such as queue length and vehicle turning or erratic movements, may be required from detectors for future traff

4、ic management applications. the choice of a detector for a specific application is, of course, dependent on many factors, including data required, accuracy, number of lanes monitored, number of detection zones per lane, detector purchase and maintenance costs, vendor support, and compatibility with

5、the current and future traffic management infrastructure. the results of this evaluation project is being presented in two parts. part 1 introduces the theory of operation and the strengths and weaknesses of the various overhead detector technologies. part 2 will provide field evaluation data and so

6、me general conclusions about detector performance and applications. copies of the final report, a set of five compact disks containing the detector evaluation data, and other reports are available from the fhwa by writing to mr. pete mills at hsr-1, 6300 georgetown pike, mclean, va 22101.note: the d

7、etector performance data presented in this article were obtained by dr. klein when he was the projects principal investigator at hughes aircraft company. introductionmaximizing the efficiency and capacity of the existing ground transportation network is made necessary by the continued increase in tr

8、affic volume and the limited construction of new highway facilities in urban, intercity, and rural areas. smart street systems that contain traffic monitoring detectors, real-time adaptive signal control systems, and motorist communications media are being combined with freeway and highway surveilla

9、nce and control systems to create smart corridors that increase the effectiveness of the transportation network. the infrastructure improvements and new technologies are, in turn, being integrated with communications and displays in smart cars and public access areas (such as shopping centers) to fo

10、rm intelligent transportation systems. vehicle detectors are an integral part of these modern traffic control systems. the types of traffic flow data, as well as their reliability, consistency, accuracy, and precision, and the detector response time are some of the critical parameters to be evaluate

11、d when choosing a vehicle detector. these attributes become even more important as the number of detectors proliferate and the real-time control aspects of its put a premium on the quantity and quality of traffic flow data, as well as the ease of data interpretation and integration into the existing

12、 traffic control system. current vehicle detection is based predominantly on inductive loop detectors (ilds) installed in the roadway subsurface. when properly installed and maintained, they can provide real-time data and a historical database against which to compare and evaluate more advanced dete

13、ctor systems. alternative detector technologies being developed provide direct measurement of a wider variety of traffic parameters, such as density (vehicles per mile per lane), travel time, and vehicle turning movement. these advanced detectors supply more accurate data, parameters that are not di

14、rectly measured with previous instruments, inputs to area-wide surveillance and control of signalized intersections and freeways, and support of motorist information services. furthermore, many of the advanced detector systems can be installed and maintained without disrupting traffic flow. the less

15、 obtrusive buried detectors will continue to find applications in the future, as for example, where aesthetic concerns are dominant or procedures are in place to monitor and repair malfunctioning units on a daily basis. newer detectors with serial outputs currently require specific software to be wr

16、itten to interpret the traffic flow parameters embedded in the data stream. since each detector manufacturer generally uses a proprietary serial protocol, each detector with a unique protocol requires corresponding software. this increases the installation cost or the real purchase price of the dete

17、ctor. furthermore, not every detector outputs data on an individual vehicle basis. while some do, others integrate the data and output the results over periods that range from tens of seconds to minutes, producing parameters that are characteristic of macroscopic traffic flow. the traffic management

18、 agency must thus use caution when comparing outputs from dissimilar detectors. in performing the technology evaluations and in analyzing the data, focus was placed on the underlying technology upon which the detectors were based 1,2. it was not the purpose of the program to determine which specific

19、 detectors met a set of requirements, but rather whether the sensing technology they used had merit in measuring and reporting traffic data to the accuracy needed for present and future applications. obviously, there can be many implementations of a technology, some of which may be better exploited

20、than others at any time. thus, a technology may show promise for future applications, but the state-of-the-art of current hardware or software may be hampering its present deployment. the detectors that were used in the technology evaluations during the field tests are listed in table 1.not all dete

21、ctors were available at all sites as shown in the footnotes to the table. a summary of the advantages and disadvantages of the detector technologies is given in table 2. some of them are application specific, implying that a particular technology may be suitable for some but not all applications. a

22、factor not addressed in this table is detector cost. this issue is again application specific. for example, a higher cost detector may be appropriate for an application requiring specific data or multiple detection zones (suitable for multiple lane coverage) that are incorporated into the more expen

23、sive detector. table 3 shows examples of overhead detector technology compatibility with several traffic management applications. the assumptions shown concerning the application dictate, in part, the appropriateness of the technology. theory of overhead detector operationthe following paragraphs gi

24、ve a brief explanation of the underlying operating principles for microwave, passive infrared, active infrared, ultrasonic, passive acoustic, and video image processor detectors. microwave radar microwave radars used in the u.s. for vehicle detection transmit energy at 10.525 ghz, a frequency alloca

25、ted by the fcc for this purpose. their output power is regulated by the fcc and certified by the manufacturer to meet fcc requirements. no further certification is required of the transportation agencies for their deployment. two types of microwave radar detectors are used in traffic management appl

26、ications. the first transmits electromagnetic energy at a constant frequency. it measures the speed of vehicles within its field of view using the doppler principle, where the difference in frequency between the transmitted and received signals is proportional to the vehicle speed. thus, the detecti

27、on of a frequency shift denotes the passage of a vehicle. this type of detector cannot detect stopped vehicles and is, therefore, not suitable for applications that require vehicle presence such as at a signal light or stop bar. the second type of microwave radar detector transmits a sawtooth wavefo

28、rm, also called a frequency-modulated continuous wave (fmcw), that varies the transmitted frequency continuously with time. it permits stationary vehicles to be detected by measuring the range from the detector to the vehicle and also calculates vehicle speed by measuring the time it takes for the v

29、ehicle to travel between two internal markers (range bins) that represent known distances from the radar. vehicle speed is then simply calculated as the distance between the two range bins divided by the time it takes the vehicle to travel that distance. since this detector can sense stopped vehicle

30、s, it is sometimes referred to as a true-presence microwave radar. passive infrared detectors passive infrared detectors can supply vehicle passage and presence data, but not speed. they use an energy sensitive photon detector located at the optical focal plane to measure the infrared energy emitted

31、 by objects in the detectors field of view. passive detectors do not transmit energy of their own. when a vehicle enters the detection zone, it produces a change in the energy normally measured from the road surface in the absence of a vehicle. the change in energy is proportional to the absolute te

32、mperature of the vehicle and the emissivity of the vehicles metal surface (emissivity is equal to the ratio of the energy actually emitted by a material to the energy emitted by a perfect radiator of energy at the same temperature). the difference in energy that reaches the detector is reduced when

33、there is water vapor, rain, snow, or fog in the atmosphere. for the approximately 20 ft (6.1 m) distances typical of traffic monitoring applications with this type of detector, these atmospheric constituents may not produce significant performance degradation. active infrared detectors active i

34、nfrared detectors function similarly to microwave radar detectors. the most prevalent types use a laser diode to transmit energy in the near infrared spectrum (approximately 0.9 micrometer wavelength), a portion of which is reflected back into the receiver of the detector from a vehicle in its field

35、 of view. laser radars can supply vehicle passage, presence, and speed information. speed is measured by noting the time it takes a vehicle to cross two infrared beams that are scanned across the road surface a known distance apart. some laser radar models also have the ability to classify vehicles

36、by measuring and identifying their profiles. other types of active infrared detectors use light emitting diodes (leds) as the signal source. ultrasonic detectors ultrasonic vehicle detectors can be designed to receive range and doppler speed data. however, the most prevalent and low-cost ultrasonic

37、detectors are those that measure range to provide vehicle passage and presence data only. the ultrasonic doppler detector that also measures vehicle speed is an order of magnitude more expensive than the presence detector. ultrasonic detectors transmit sound at 25 khz to 50 khz (depending on the man

38、ufacturer). these frequencies lie above the audible region. a portion of the transmitted energy is reflected from the road or vehicle surface into the receiver portion of the instrument and is processed to give vehicle passage and presence. a typical ultrasonic presence detector transmits ultrasonic

39、 energy in the form of pulses. the measurement of the round-trip time it takes for the pulse to leave the detector, bounce off a surface, and return to the detector is proportional to the range from the detector to the surface. a detection gate is set to identify the range to the road surface and in

40、hibit a detection signal from the road itself. when a vehicle enters the field of view, the range from the detector to the top of the vehicle is sensed, and being less than the range from the detector to the road, causes the detector to produce a vehicle detection signal.passive acoustic detectors v

41、ehicular traffic produces acoustic energy or audible sound from a variety of sources within the vehicle and from the interaction of the vehicles tires with the road surface. arrays of acoustic microphones are used to pickup these sounds from a focused area within a lane on a roadway. when a vehicle

42、passes through the detection zone, the signal-processing algorithm detects an increase in sound energy and a vehicle presence signal is generated. when the vehicle leaves the detection zone, the sound energy decreases below the detection threshold and the vehicle presence signal is terminated. 車輛檢測技

43、術(shù)在交通管理上的應(yīng)用第1部分勞倫斯·克萊因顧問10種不同的檢測技術(shù)最近為聯(lián)邦公路管理局贊助的智能車輛公路系統(tǒng)節(jié)目的一部分而被評估了。這個(gè)節(jié)目的兩個(gè)主要目標(biāo)是：1. 以確定未來的智能交通系統(tǒng)（its）應(yīng)用的交通參數(shù)和相應(yīng)的測量精度，2. 為了執(zhí)行實(shí)驗(yàn)室和現(xiàn)場測試的道路上的安裝，地表和地下檢測器，以確定它們的性能。所有測試技術(shù)的代表性檢測器被發(fā)現(xiàn)滿足當(dāng)前交通管理的要求。但無論怎樣,，提高精度和新的信息類型，如隊(duì)列長度和車輛轉(zhuǎn)彎或不穩(wěn)定的運(yùn)動，在未來的交通管理應(yīng)用中可能需要使用檢測器。一個(gè)特定的應(yīng)用程序的檢測器的選擇，當(dāng)然，依賴于許多因素，包括所需的數(shù)據(jù)，精度，監(jiān)測車道的數(shù)量，每通道的檢測

44、區(qū)域，檢測器采購和維護(hù)成本，供應(yīng)商的支持，并與當(dāng)前和未來的交通管理基礎(chǔ)設(shè)施的兼容性。本評估節(jié)目的結(jié)果被分為兩部分。第1部分介紹了工作原理和各種檢測技術(shù)的優(yōu)勢和弱點(diǎn)。第二部分將提供現(xiàn)場評價(jià)數(shù)據(jù)和一些檢測器的性能和應(yīng)用的一般性結(jié)論?？偨Y(jié)報(bào)告的副本中，包含了一組5個(gè)檢測器的評價(jià)數(shù)據(jù)光盤，其他的皮特·米爾斯先生在弗吉尼亞州22101麥克萊恩的6300喬治敦派克的高鐵1號線上寫的報(bào)告可從聯(lián)邦公路管理局里得到。注：在這篇文章中提出的檢測器性能數(shù)據(jù)，是克萊因博士他在休斯飛機(jī)公司作為該項(xiàng)目的首席研究員時(shí)獲得的。引言在交通量的不斷增加和有限的建設(shè)新的城市，城際，農(nóng)村的公路設(shè)施，最大限度地發(fā)揮現(xiàn)有的地面

45、交通網(wǎng)絡(luò)的效率和能力是有必要的。街道智能系統(tǒng)，包含流量監(jiān)控檢測器，實(shí)時(shí)自適應(yīng)信號控制系統(tǒng)，駕車通信媒體正在與高速公路和公路的監(jiān)測和控制系統(tǒng)相結(jié)合，以創(chuàng)建智能走廊，增加的交通運(yùn)輸網(wǎng)絡(luò)的有效性。反過來，基礎(chǔ)設(shè)施的改善和新技術(shù)與通信工具和智能汽車和公共接入領(lǐng)域（如商場）的集成顯示，形成智能交通系統(tǒng)。車輛檢測器是這些現(xiàn)代化的交通控制系統(tǒng)的基本組成部分。當(dāng)選擇一個(gè)車輛檢測器對交通數(shù)據(jù)流，以及它們的可靠性，一致性，準(zhǔn)確性和精確度，和檢測器響應(yīng)時(shí)間等一些關(guān)鍵參數(shù)進(jìn)行評估。隨著檢測器數(shù)量的激增，這些屬性變得更加重要和把流量數(shù)據(jù)的數(shù)量和質(zhì)量，以及對數(shù)據(jù)的解釋的智能交通系統(tǒng)的實(shí)時(shí)控制方面，集成到現(xiàn)有的交通控制系統(tǒng)

46、中。目前的車輛檢測器主要是安裝在地下巷道的感應(yīng)線圈檢測器（ilds）。當(dāng)正確安裝和維護(hù)時(shí)，它們可以提供實(shí)時(shí)數(shù)據(jù)和歷史數(shù)據(jù)庫作比較可以評估更先進(jìn)的檢測系統(tǒng)。替代檢測技術(shù)正在開發(fā)提供一個(gè)更廣泛的交通參數(shù)，如密度（每公里每車道的車輛），旅行時(shí)間，車輛轉(zhuǎn)向運(yùn)動等的直接測量。這些先進(jìn)的檢測器提供更準(zhǔn)確的數(shù)據(jù)，參數(shù)不是原來的儀器投入到大面積的監(jiān)測和控制信號的路口和高速公路直接測量的，以及駕駛者的信息服務(wù)的支持。此外，許多先進(jìn)的檢測系統(tǒng)可以安裝并保持不中斷交通流。一些稀少的地埋檢測器將繼續(xù)尋找在未來的應(yīng)用，例如，在審美方面的問題上主導(dǎo)或程序地方監(jiān)測和修復(fù)故障單元在日常基礎(chǔ)。目前較新的串行輸出的檢測器需要特定

47、的軟件，要寫入解釋嵌入在數(shù)據(jù)流中的交通流參數(shù)。由于每個(gè)檢測器制造商普遍采用了專有的串行協(xié)議，每個(gè)擁有一個(gè)獨(dú)特的協(xié)議的檢測器需要相應(yīng)的軟件。這增加了安裝成本或檢測器的實(shí)際購買價(jià)格。此外，并不是每個(gè)檢測器都輸出個(gè)別車輛的基礎(chǔ)數(shù)據(jù)。雖然有些在做，有些在整合從幾十秒鐘到幾分鐘期間該范圍內(nèi)的數(shù)據(jù)和輸出結(jié)果，生產(chǎn)參數(shù)是宏觀交通流的特點(diǎn)。因此，當(dāng)比較不同的檢測器輸出的時(shí)候，交通管理機(jī)構(gòu)必須謹(jǐn)慎使用。在執(zhí)行技術(shù)評估和分析數(shù)據(jù)時(shí)，重點(diǎn)是放在基于底層技術(shù)1,2的該檢測器上。這不是確定滿足一系列要求的具體檢測器的用途，而是在于他們是否使用傳感技術(shù)測量交通數(shù)據(jù)并報(bào)告流量數(shù)據(jù)，為現(xiàn)在和未來的應(yīng)用提供準(zhǔn)確的需要。明然，可

48、以有許多實(shí)現(xiàn)技術(shù)的裝置，其中一些在任何時(shí)候可能比另外一些更好地被利用。因此，這種技術(shù)可能會在未來的應(yīng)用中被實(shí)現(xiàn)，但當(dāng)前的硬件或軟件的狀態(tài)可能會阻礙其目前的發(fā)展。在技術(shù)評估過程中實(shí)地測試使用的檢測器，在表1中列出。并非在表格的所有注腳中顯示的所有的檢測器可以使用。表2給出了檢測技術(shù)的優(yōu)點(diǎn)和缺點(diǎn)的一個(gè)總結(jié)。其中一些有著特定的用途，這意味著一個(gè)特定的技術(shù)可能適合一些，但并非所有的應(yīng)用。本表中未涉及的一個(gè)因素是檢測器的成本。這個(gè)問題也是具體的應(yīng)用。例如，較高的成本檢測器可能需要具體的數(shù)據(jù)的應(yīng)用或多個(gè)檢測區(qū)域（適用于多車道覆蓋）被歸納入更昂貴的檢測器是適當(dāng)?shù)?。?顯示了以上提到的檢測技術(shù)在幾個(gè)交通管理應(yīng)用方面的兼容性的例子。假設(shè)顯示有關(guān)應(yīng)用的要求，部分的，適當(dāng)?shù)募夹g(shù)。以上檢測器的操作理論以下