外文翻譯--車(chē)輛檢測(cè)技術(shù)在交通管理上的應(yīng)用-交通線路(已改無(wú)錯(cuò)字)
2023-07-06 05:49:36 本頁(yè)面
【正文】 ot produce significant performance degradation. Active Infrared Detectors Active infrared detectors function similarly to microwave radar detectors. The most prevalent types use a laser diode to transmit energy in the near infrared spectrum (approximately micrometer wavelength), a portion of which is reflected back into the receiver of the detector from a vehicle in its field 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 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 lowcost ultrasonic 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 manufacturer). 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 energy in the form of pulses. The measurement of the roundtrip 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 inhibit 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 Vehicular traffic produces acoustic energy or audible sound from a variety of sources within the vehicle and from the interaction of the vehicle’s 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 passes through the detection zone, the signalprocessing 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(chē)輛檢測(cè)技術(shù) 在 交通管理 上的 應(yīng)用 第 1 部分 勞倫斯克萊因 顧問(wèn) 10 種 不同的檢測(cè)技術(shù)最近為聯(lián)邦公路管理局贊助的智能車(chē)輛公路系統(tǒng) 節(jié)目的 一 部分 而被評(píng)估了 。這個(gè) 節(jié)目 的 兩個(gè) 主要目標(biāo)是： 1. 以確定未來(lái)的智能交通系統(tǒng)（ ITS）應(yīng)用的交通參數(shù)和相應(yīng)的測(cè)量精度， 2. 為了執(zhí)行實(shí)驗(yàn)室和 現(xiàn)場(chǎng)測(cè)試的道路 上的 安裝，地表和地下 檢測(cè)器 ，以確定 它 們的 性能 。 所有測(cè)試技術(shù) 的代表性檢測(cè)器 被發(fā)現(xiàn)滿足當(dāng)前交通管理的要求。但無(wú)論怎樣 ,，提高精度和新的信息類(lèi)型 ， 如隊(duì)列長(zhǎng)度和車(chē)輛轉(zhuǎn)彎或不穩(wěn)定的運(yùn)動(dòng)，在未來(lái)的交通管理應(yīng)用 中 可能需要 使用檢測(cè)器 。一個(gè)特定的應(yīng)用程序的 檢測(cè)器 的選擇，當(dāng)然，依賴(lài)于許多因素，包括所需的數(shù)據(jù)，精度，監(jiān)測(cè)車(chē)道的數(shù)量，每通道的檢測(cè)區(qū)域， 檢測(cè)器 采購(gòu)和維護(hù)成本，供應(yīng)商的支持，并與當(dāng)前和未來(lái)的交通管理基礎(chǔ)設(shè)施 的 兼容性。 本評(píng)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(cè)技術(shù)的優(yōu)勢(shì)和弱點(diǎn)。第二部 分將提供現(xiàn)場(chǎng)評(píng)價(jià)數(shù)據(jù)和一些 檢測(cè)器 的性能和應(yīng)用 的 一般性結(jié)論?？?
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