【作者】 王勇；

【导师】 傅星；

【作者基本信息】 天津大学 ， 测试计量技术及仪器， 2005， 硕士

【摘要】 铁路运输在我国的交通运输系统中占据着非常重要的地位,因此如何保证铁路运输的安全是一个非常重要的课题。其中对铁路钢轨的定期检测是保证铁路运行安全的重要保障之一。便携式的钢轨超声探伤仪是我国目前铁路钢轨检测的主要手段。本文在认真调研和深入分析的基础上,对现有的钢轨超声探伤仪所存在的难以准确判断伤损的问题,研究开发了以DSP为核心的数字式钢轨超声探伤仪。它相比较旧式模拟探伤仪有很多优点:伤损判断更加准确;具有自动报警功能,可以防止操作人员的人为失误;检测的结果可通过USB口或RS232口转存到计算机中或其它的存储设备中,便于日后的进一步分析;可以在检测的过程中对采集到的数据实时进行各种算法处理,实现更加强大的功能,使检测更加准确;用液晶屏显示代替传统的示波管显示,操作界面更加友好,显示内容更加丰富。从而降低了人工劳动强度,大大提高检测的效率和准确性。具体完成的工作有:(1)本论文对超声检测理论与技术进行了仔细地研究,自行设计开发了以DSP和MCU为核心的数字式钢轨超声探伤仪。系统由模拟电路和数字电路组成,模拟电路完成超声的发射接收及信号的调理,数字电路完成信号处理和波形显示等功能。(2)对超声波与钢轨中伤损的相互作用的机理进行了研究,对超声回波信号进行了认真的分析,设计了回波抑制及增益补偿模型,并编制了软件,实验表明模型对提高对伤损的判断准确度有重要的作用。(3)设计了一种新的数据采集压缩算法,将数据的采集和压缩有机的融合到一起,在采集率为14M时,实现1～6倍的压缩率,提高了有效信号的捕捉能力,从而提高了检测的准确度。(4)最后对超声探伤仪的各项基本功能进行了验证,并且对整机进行了实验,并且对实验结果及误差进行了分析。更多还原

【Abstract】 Railage takes a very important role in the system of traffic, so regularly testing therail is one of main methods to guarantee the safe of railage. A portable instrumentwith ultrasonic to detect the rail is the main means used for testing the railroad inChina nowadays. This type of instrument is based on analog technology. It can onlyprocess the collected ultrasonic signal simplely and is not easy to use. The incorrectresult is easily got because operators can only estimate the flaw in the rail by watchingthe ultrasonic waveform on the screen. Moreover the function of processing the dataof this instrument is not very good.This dissertation brings forward a new project to resolve the disadvantages of theold type of instrument. Its main idea is to develop a new type of instrument based onsignal processing technology. It will have many advantages contrast to the old ones,such as detection is more precision, can give an alarm automatically when find theflaw and can prevent the mistake made by operators, the data can be recorded tocomputer or other memory for future analyse, can realize the more complicatedfunction when detect the rail, use LCD to enrich the content displayed, so it is easy touse and raise the efficiency of detection.Main works having been achieved are following:1. In this dissertation the theory and technology of detection used ultrasonic wasdetail studied, and a kind of digital Portable Rail Detector mainly based on DSP andMCU was developed. The system was made up of analog circuit and digital circuit.The function of analog circuit was to emit and receive the ultrasonic, adjust thereceived signal;the function of digital circuit was to process the received signal anddisplay waveform.2. The interaction between ultrasonic and flaw in rail was researched, the ultrasonicecho was analyzed. The model of echo restraining and gain compensation wasdesigned;the software on the basis of this model was programmed. This model wasproved very effective for accurate detecting the flaw in the rail with experiments.3. A new kind of collect and compress algorithm was designed combining collectwith compress. Up to six times compressing ratio was realized when the collectionratio was 14M. The ability of capturing the effective signal and the accuracy ofdetection was raised.4. The basic functions of the Digital Flaw Detector with ultrasonic was verified byexperiments, the result of experiments and error were analyzed.更多还原