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1、外文文獻(xiàn)翻譯在導(dǎo)盲應(yīng)用中的超聲波動(dòng)態(tài)距離修正系統(tǒng) Robert X.Gao,Member,IEEE and Chuan Li Institute for micromanufacturing Louisiana Tech University P.O.Box 10348 Ruston,LA 71272 USA摘要：一個(gè)基于以微處理器為基礎(chǔ)的超聲波距離修正系統(tǒng)已被設(shè)計(jì)出來(lái)，它的兩個(gè)管腳之間用類似PVC管來(lái)封裝。此系統(tǒng)，作為盲人導(dǎo)盲應(yīng)用，它管腳里面包含四個(gè)超聲波傳感器做為一個(gè)整體，外加一個(gè)微處理器從而構(gòu)成了這個(gè)系統(tǒng)。它可以實(shí)時(shí)提供使用者前進(jìn)的道路上最大大約5米的距離內(nèi)所遇到的障礙物的距離和高度信息

2、。在實(shí)驗(yàn)室進(jìn)行各種移動(dòng)模式的測(cè)試中，在5米的范圍內(nèi)最大的相關(guān)測(cè)量誤差低于14%。當(dāng)測(cè)量范圍為3米時(shí)，這個(gè)誤差還會(huì)降低到5%。把此系統(tǒng)整體小型化后，可以做為盲人的日常導(dǎo)盲的應(yīng)用。關(guān)鍵詞：盲人導(dǎo)盲，導(dǎo)盲棒，傳感器集成，設(shè)備小型化1 緒論過(guò)去的十年表明，醫(yī)學(xué)工程已經(jīng)取得了巨大的進(jìn)步。醫(yī)療設(shè)備的商業(yè)化有著寬廣的前景，它能為殘疾人充分的提供一個(gè)更為舒適的生活環(huán)境。然后，科技的進(jìn)步，似乎還沒對(duì)電子導(dǎo)盲（ETAs）領(lǐng)域產(chǎn)生太多的影響。雖然一個(gè)ETAs產(chǎn)品可以造就一個(gè)行業(yè)，但是，盲人群體可以接受的費(fèi)用是低的令人吃驚。即使是現(xiàn)在，大部分的盲人還是在選用傳統(tǒng)的拐杖來(lái)作為自己首選的出行輔助工具，它可以提供給使用者一

3、個(gè)半徑約為1米的弧形的延伸空間來(lái)感覺是否有障礙物。但是，使用拐杖來(lái)作為盲人的輔助工具，它有有不可克服的局限性，它不能為使用者提供腰至頭部的保護(hù)。因此，使用拐杖作為盲人的出行輔助工具，它潛在的危險(xiǎn)非常的高。近年來(lái)，微電子電路的高速發(fā)展，這為拐杖植入嵌入式微傳感器提供了機(jī)會(huì)，它可以在傳統(tǒng)的外觀和功能上，再增加額外的功能，使基于傳統(tǒng)的拐杖上，功能變的更為完善，它可以為使用者提供更為寬廣的障礙物提示報(bào)警功能。在這篇論文中，將呈現(xiàn)出上述盲人導(dǎo)盲棒的設(shè)計(jì)和測(cè)試。實(shí)驗(yàn)室的測(cè)試實(shí)驗(yàn)包含有不同的典型的障礙物和導(dǎo)盲棒不同的移動(dòng)方式測(cè)試，用于提高傳感器整體化導(dǎo)盲棒的適用性，以求能為盲人的日常出行提供方便。盲人行走中

4、所產(chǎn)生的不足之處仍然很多。目前并沒廣泛接受ETA可能是因?yàn)闆]有在心理上接受TEA設(shè)計(jì)者組織和制造商，缺乏吸引潛在用戶，或者是因?yàn)槟壳鞍l(fā)展的現(xiàn)有技術(shù)還不能實(shí)現(xiàn)一個(gè)復(fù)雜并且有成本效益，可依賴的人類環(huán)境改造學(xué)產(chǎn)品。2 原理障礙物的測(cè)量是基于超聲波的回聲測(cè)量。如下圖1是障礙物與四個(gè)（Tr1Tr4）一體化超聲波變換器的的方位模型。傳感器Trl，工作頻率40KHz，是配置一個(gè)發(fā)射器和一個(gè)接收器，Trl僅作為一個(gè)接收器。障礙物與手杖持有人的水平距離（D），以及手杖的垂直高度（H）可以由下面式子得到：信號(hào)傳輸路徑L1和L2都取決于測(cè)量周期的開始到接收到Tr1和Tr2的回聲的傳播時(shí)間，參數(shù)1-4通過(guò)變換器設(shè)置決

5、定。手杖與地之間的角度和手杖頂端到地面的距離L4，考慮由于手杖在實(shí)際中運(yùn)動(dòng)情況造成的測(cè)量誤差，由輔助傳感器Tr3和Tr4決定。圖1 障礙物的識(shí)別3 試驗(yàn)為了證明傳感器集成技術(shù)，實(shí)驗(yàn)室用三個(gè)典型的對(duì)象來(lái)引證：1）直徑為20cm的無(wú)形花盆，2）截面為10mm10mm桿長(zhǎng)為1.7m的木桿和3）一個(gè)40毫米的鋼球。這些對(duì)象被掛在一個(gè)離地面高度約1.7米，到手杖的距離為5米內(nèi)。兩個(gè)超聲波測(cè)距模塊用作Tr1和Tr2。對(duì)于Tr3和Tr4，兩個(gè)模塊在馬薩產(chǎn)品中得到應(yīng)用。這些與1.5長(zhǎng)PVC管和5厘米的二步格成為一體。數(shù)據(jù)的采集和處理協(xié)調(diào)由摩托羅拉的微處理器M68HC711E9控制（圖2）。高度和距離信息是通過(guò)

6、從5米每遠(yuǎn)漸漸移動(dòng)手杖到掛著的對(duì)象獲得的，每25厘米采集一次數(shù)據(jù)。為了模擬手杖的實(shí)際使用，手杖作為接近的對(duì)象，它經(jīng)歷了三種類型的議案：手杖末端放到地面時(shí)，離末端15厘米左右的電弧，離末端5厘米的助聽器，兩個(gè)成為一個(gè)組合。所獲得的數(shù)據(jù)再與用工業(yè)尺進(jìn)行比較。如圖3所示，高度測(cè)量的最大的相對(duì)誤差小于14%；對(duì)于遠(yuǎn)距離的測(cè)量，測(cè)量誤差在12%以內(nèi)。測(cè)量精度隨著用戶接近障礙而迅速提高：在3米以內(nèi)的距離，誤差迅速下降到小于5%，這意味著一個(gè)更好的保護(hù)。圖2 系統(tǒng)構(gòu)造圖3遠(yuǎn)距測(cè)量和高度測(cè)量的誤差4 結(jié)論手杖用戶面前，超聲波傳感器陣列在局部移動(dòng)的路徑障礙里是有效的。測(cè)量精度的提高可以通過(guò)系統(tǒng)的修改和應(yīng)用誤差補(bǔ)

7、償技術(shù)。今后的工作包括硬件和軟件的優(yōu)化，包括其他對(duì)象的領(lǐng)域測(cè)試和使用微制造技術(shù)的最小化系統(tǒng)。A DYNAMIC ULTRASONIC RANGING SYSTEMAS A MOBILITY AID FOR THE BLINDRobert X. Gao, Member, IEEE and Chum LiInstitute for MicromanufacturingLouisiana Tech UniversityP.O. Box 10348Ruston, LA 71272 USAAbstract - A microprocessor-based ultrasonic ranging syste

8、m, configured around a PVC tube resembling the form of a long cane, has been designed. The system, intended to serve as a mobility aid for the blind, consists of four ultrasonic sensors integrated into the cane, and a microcontroller.It is able to provide real-time information on the distance and he

9、ight of over-hanging obstacles within 5 meters along the travel path ahead of the user. Lab experiments under various cane motion patterns have shown that at 5 meters, the maximum relative error of the measurement is below 14%. This drops to less than 5%, when the measurement range is within 3 meter

10、s. Uponminiaturization, the system can be integrated into a conventional long cane for practical daily use by the blind.(Keywords: mobility aid for the blind, long cane, sensorintegration, device miniaturization)I. INTRODUCTIONThe past decades have witnessed tremendous technological progress in biom

11、edical engineering. A wide range of rehabilitation equipments have been commercialized, contributing Substantially to creating a more comfortable living environment for the disabled. Nevertheless, in the field of electronic travel aids (ETAs) for the blind, the research efforts seem to have made les

12、s impact. Although a variety of ETAs have been made commercially available l-31, their acceptance rate by the blind community remains surprisingly low 4. Up until now, the majority of blind are still using the traditional long cane as their primary travel aid, which provides an extended spatial sens

13、ing within an arc of the shoulders width about 1 m ahead of the user. However, due to its inherent limitation, the use of a long cane does not provide protection for the user between hisher waist and head. Thus, the potential for injuries arising from blind walking remains very high. The lack of a w

14、idely acceptable ETA so far may either be due to the lack of understanding of the psychological aspects of the blind community from the ETA designers and manufacturers and subsequently, the lack of appeal of the products to the potential users, or its because the technology available at the time of

15、the development was not suflicient to enable a sophisticated yet cost-effective, reliabde and ergonomic product.The rapid development of the emerging microelectromechanical systems (MEMS) technologies in recent years has opened up opportunities for introducing a new type of microsensor-embedded long

16、 cane which, while maintaining the same appearance and function %1s its Wtional counterpart, is capable of perceiving overhangiig obstacles outside the detectable range ofthe conventional canes, thus providing a substantiallybetter protection of its users. In this paper, the design and performance t

17、ests of aprototype of such a system is presented. Laboratory experiments; involving different representative obstacles and various cane motion patterns have verified the applicability of such a sensor-integrated long cane for thepractical daily use by the blind people.11. PRINCIPLEThe obstacle detec

18、tion is based on the echo-time measurement. Schematically shown in Fig. l is an instantaneous position of the prototype cane with four integrated ultrasonic transducers T, - T,. Transducer Trl, working at 40 1Hz, is configured both as a transmitter and a receiver whereas Tfl works only as a receiver

19、. The horizontal distance (D) of an obstacle (OBJ) to the cane holder and its vertical height 0 can be given as:The signal trave1,pziths L, and L, are determined by the time elapsed between the start of the measurement cycle and the receipt of the echos from T, and Ta. Parameters 6, - S, are given b

20、y the transducer setup. The angle ct between the cane and the ground and the distance L, from the cane tip to the ground take into account the measurement errors caused by the cane motion in a realistic situation, and are determined by the auxiliary transducers Tr3 and T,.III. EXPERIMENTSTo veri the

21、 sensor-integration technique, lab experiments were conducted using three representative objects: 1) aplastic flowerpot about 20 cm in diameter, 2) a 1.7 m long wood rod with a cross section of 10 mm x 10 mm, and 3) a 40 mm steel ball. These objects were hung at a height of about 1.7 meters above th

22、e ground, within a distance of about 5 m from the cane. Two Polaroid ultrasonicrsfnging modules were used for T, and Ta. For TI:,a nd TF(t,w o modules from the Massa Products were applied. These were integrated into a PVC tube about 1.5 m long and 5 cm in dimeter. The coordination of the data acquis

23、ition and processing were controlled by a Motorolamicroprocessor M68HC711E9 (Fig. 2). The height and distance information were obtained by moving the cane from a 5 m distance gradually to the hanging object, with the data taken at an interval of every 25 cm. To simulate the realistic cane use, as th

24、e cane approached to the object, it underwent three types of motions: arcing of the cane tip of about 15 cm to the left and right, tapping of the cane tip on the ground, with the tip lift being about 5 cm, and a combination of the two. The data obtained were then compared with the measurements using

25、 an industrial ruler. As shown in Fig. 3, the maximum relative error of the height measurement is less than 14%; for the distance measurement, its within 12%.The measurement accuracy increases rapidly as the user moves closer to the obstacle: within a range of 3 meters, the error drops quickly to le

26、ss than 5%, meaning a better protection.IV. CONCLUSIONSThe ultrasonic sensor array is effective in localizing obstacles within the travel path in front ofthe cane user. The measurement accuracy can be increased through system modification and applying error compensation techniques. Future work inclu

27、de hardware and software optimization, field tests involving othere objects, and system miniaturiration using various micromanufacturing techniques.ACKNOWLEDGEMENTThis research was supported by the National Science Foundation under grant BES-9402818. The authors thank M. Rasbury and J. Cook for fabr

28、icating the test devices.REFERENCES1 L. Kay, Electronic Aids for Blind Persons: An InterdisciplinarySubject, IEE Proceedings, Vol. 131, No. 7, pp. 559-576, 1984.2 A. Dodds, J. Armstrong, and C. Shingledecker, The Nottingham Obstacle Detector: Development and Eevaluation, J. of Visual and Blindness, Vol. 75, pp.203-206, May, 1981.3 A. Heyes, The Sonic Pathfinder A New Electronic Travel Aid, J; of Visual Impairment and Blindness, Vol. 78,No. 5, pp. 200-202, May, 1984.4 M. Sanders and E. McComick, Human Factors in Engineering and Design, 7th edition, McGraw-Hill, Inc.,1993.9