汽車的轉(zhuǎn)向控制外文翻譯

1、<p><b>　　中文4370字</b></p><p><b>　　交通與汽車工程學院</b></p><p>　　本科生畢業(yè)設(shè)計（論文）</p><p><b>　　英文翻譯</b></p><p>　　學生姓名：

2、 </p><p>　　學 號： </p><p>　　專 業(yè)： 汽車服務(wù)工程 </p><p>　　年 級： </p><p>　　指導教師： <

3、;/p><p>　　日 期： 二00九年五月二十日 </p><p><b>　　汽車的轉(zhuǎn)向控制</b></p><p>　　Ashley, Steven</p><p>　　www.encyclopedia.com</p><p>　　摘要：控制系統(tǒng)穩(wěn)定性是針對提高駕駛安全性提出的一系

4、列措施中最新的一個。這個系統(tǒng)能夠在40毫秒內(nèi)實現(xiàn)從制動開始到制動恢復的過程，這個時間比人的反應(yīng)時間快七倍。它們通過調(diào)整汽車扭矩或者通過應(yīng)用汽車左側(cè)或右側(cè)制動，如果需要甚至兩者兼用，來實現(xiàn)準確的行車路線。這個系統(tǒng)已被應(yīng)用于奔馳S600汽車了。穩(wěn)定的機械制動系統(tǒng)能夠在制動時發(fā)現(xiàn)打滑，并且在駕駛?cè)藛T反應(yīng)以前實現(xiàn)車輛的減速。在這篇文章中，我們認識了ESP優(yōu)于ABS防抱死系統(tǒng)和牽引控制系統(tǒng)的地方，同時了解了ESP對轉(zhuǎn)向控制的原理，以及該系統(tǒng)中偏航

5、比率回轉(zhuǎn)儀的工作原理。</p><p>　　關(guān)鍵字：穩(wěn)定控制，ESP，ABS，偏航比率回轉(zhuǎn)儀</p><p>　　安全玻璃，安全帶，撞擊緩沖區(qū)，安全氣囊，ABS系統(tǒng)，牽引力控制系統(tǒng)直到現(xiàn)在的穩(wěn)定調(diào)節(jié)系統(tǒng)，汽車安全系統(tǒng)的連續(xù)升級，已經(jīng)產(chǎn)生了一種為保護汽車所有者安全的設(shè)計模式。穩(wěn)定調(diào)節(jié)系統(tǒng)幫助駕駛員從不可控制的曲線制動中解脫出來，從而避免了汽車的擺動滑行和交通事故。</p>&l

6、t;p>　　利用計算機和一系列傳感器，穩(wěn)定調(diào)節(jié)系統(tǒng)能夠檢測到制動輪的打滑并且比人更快的恢復對汽車的方向控制。系統(tǒng)每百萬分之一秒做出一次快速捕捉，以及判斷汽車是否在按照駕駛員的路線行駛。如果檢測到汽車行駛路線和駕駛員駕駛路線存在一個微小的偏差，系統(tǒng)會在瞬間糾正發(fā)動機扭矩或者應(yīng)用汽車左右制動。該過程的標準反應(yīng)時間是40毫秒----人的平均反應(yīng)時間的七分之一。</p><p>　　羅伯特博世工程系統(tǒng)負責人安東&#

7、183;范·桑特解釋說：“一個穩(wěn)定的控制系統(tǒng)能夠‘感覺到’駕駛員想要運動的方向，通過控制轉(zhuǎn)向角度，油門踏板的位置，制動板的狀態(tài)來確定汽車實際運動路線的偏航比率（汽車偏離方向軸的角度）和橫向加速度”。項目負責人阿明·馬勒領(lǐng)導著范桑特的工作小組和奔馳汽車公司的工程師發(fā)明了第一個完全有效的穩(wěn)定調(diào)節(jié)系統(tǒng)，該系統(tǒng)由發(fā)動機扭矩控制系統(tǒng)、制動系統(tǒng)和牽引控制系統(tǒng)組成以實現(xiàn)理想與現(xiàn)實運動之間的最小差距。</p><

8、p>　　汽車安全專家相信穩(wěn)定調(diào)節(jié)系統(tǒng)能夠減少交通事故的發(fā)生，至少是在傷亡嚴重的事故方面。安全統(tǒng)計表明，多數(shù)的單車撞擊事故傷亡（占傷亡事故發(fā)生的4%）事故能夠通過應(yīng)用這項新技術(shù)避免。這項新系統(tǒng)的額外費用主要用于目前汽車日益普遍應(yīng)用的制動/牽引控制鎖組件。</p><p>　　穩(wěn)定調(diào)節(jié)系統(tǒng)技術(shù)首次應(yīng)用于歐洲的奔馳S600汽車，是由德國斯圖加特市的羅伯特博世公司和奔馳公司在過去幾年共同研制的。該系統(tǒng)在博世公司被稱

9、為汽車動力控制（VDC），而默西迪稱它為穩(wěn)定電控系統(tǒng)（ESP），作用就是在任何狀況下維持車輛的穩(wěn)定性。博世公司開發(fā)了這項系統(tǒng)，奔馳公司把它應(yīng)用于車輛。工程師默西迪絲在柏林應(yīng)用戴姆勒奔馳汽車虛擬駕駛模擬器在極限情況下對系統(tǒng)進行評估，例如極強的側(cè)風。然后他們在瑞典的安杰普勞附近的后娜瓦安湖的冰面上進行性能測試。工作通常是在公路上進行以適用于公共汽車和大卡車，例如避免的折合問題。</p><p>　　穩(wěn)定調(diào)節(jié)系統(tǒng)在19

10、95年中應(yīng)用于歐洲S系列產(chǎn)品上，隨后在1996年進入美國市場。用戶可以選擇750美元的系統(tǒng)，就像應(yīng)用于默西迪絲的試驗用的V8發(fā)動機上的，也可以選擇價格為2400美元的應(yīng)用于六缸發(fā)動機汽車的系統(tǒng)。后者的系統(tǒng)中差不多有1650美元是用于牽引控制系統(tǒng)，該系統(tǒng)是穩(wěn)定性系統(tǒng)的先決條件。</p><p>　　并不是只有博世公司一家在開發(fā)這樣的安全系統(tǒng)，美國密歇根州的ITT（美國國際電信公司）汽車公司的奧伯恩·希爾，

11、在1995年1月底特律北美國際汽車展覽會上展示用戶管理系統(tǒng)（ASMS），“車輛控制器應(yīng)該像空對地導彈的控制器那樣，比較而言，事實上那已經(jīng)實現(xiàn)了，不同的是兩者的費用不同”，美國國際電信公司駐歐洲空對地導彈控制工程負責人約翰尼斯·格雷得說。北美ITT公司“汽車制動和底盤工程”主管湯姆·麥茲指出，在未來十年美國國際電信公司的系統(tǒng)要首先出現(xiàn)在車輛上。很多工程師正在六輛特殊制造的精密車輛模型上調(diào)試這種系統(tǒng)。</p>

12、<p>　　一個比較簡單和較低效率的博世的穩(wěn)定調(diào)節(jié)系統(tǒng)也在1995年出現(xiàn)在慕尼黑寶馬公司的AG系列750iL和850Ci V-12兩款車上。寶馬公司的穩(wěn)定調(diào)節(jié)系統(tǒng)（DSC）運用的車輪速度傳感器同牽引控制系統(tǒng)和標準ABS防抱死系統(tǒng)一樣能夠識別外部情況，使車輛更容易實現(xiàn)曲線行駛和轉(zhuǎn)彎。為了檢測出車輛轉(zhuǎn)彎時潛在的危險，DSC系統(tǒng)檢測的是兩前輪在轉(zhuǎn)彎時的速度差，DSC系統(tǒng)添加了一個更高級的角度傳感器利用現(xiàn)有的一個車輛速度，并且引入

13、了它自身帶有的關(guān)于完全抱死系統(tǒng)，牽引控制系統(tǒng)，穩(wěn)定調(diào)節(jié)系統(tǒng)軟件控制原理。</p><p>　　新的博世和ITT自動穩(wěn)定調(diào)節(jié)系統(tǒng)得益于航空工業(yè)高級技術(shù)的發(fā)展，就像超音速發(fā)動機。汽車的穩(wěn)定調(diào)節(jié)單元運用一個基于計算機系統(tǒng)的傳感器來調(diào)和人與系統(tǒng)之間的，還有輪胎與地面之間差異。另外，系統(tǒng)采用了用于導彈制導系統(tǒng)的回旋傳感器。</p><p>　　優(yōu)于ABS防抱死系統(tǒng)和牽引控制系統(tǒng)之處:</p&g

14、t;<p>　　根據(jù)范·桑特和博世公司的瑞娜·伊哈德，杰瑞·帕夫在《汽車工程師》雜志所提到的，穩(wěn)定調(diào)節(jié)系統(tǒng)是ABS防抱死系統(tǒng)和牽引控制系統(tǒng)的合理擴展。但是ABS系統(tǒng)的作用發(fā)生在制動時車輪轉(zhuǎn)向?qū)⒈绘i死時，牽引控制是預(yù)防加速時的車輪滑動，穩(wěn)定系統(tǒng)是當汽車自由轉(zhuǎn)向時能獨立于駕駛員作出操作。依靠不同的駕駛狀況，系統(tǒng)可以使每個車輪制動或者迅速使四個輪轉(zhuǎn)速適合于發(fā)動機的扭矩，從而使車輛穩(wěn)定和減少由于制動失

15、控帶來的危險。新系統(tǒng)不僅僅控制完全制動還可以作用于部分制動、行車路線、加速度、車輪與發(fā)動機動作的滯后等，這些是ABS防抱死系統(tǒng)和牽引控制系統(tǒng)所遠遠不能達到的。</p><p>　　三種主動的安全系統(tǒng)的作用時刻是一致的，那就是一個車輪被鎖死或者車輪漸漸失去方向穩(wěn)定性或者車輪使得行駛更加困難。如果一輛車必須在較低摩擦系數(shù)的路面制動，必須避免車輪抱死以保持行駛穩(wěn)定性和可駕駛性。</p><p>

16、　　ABS防抱死系統(tǒng)和牽引控制系統(tǒng)能夠預(yù)防側(cè)滑，而穩(wěn)定性系統(tǒng)采取減少側(cè)面受力的穩(wěn)定措施。如果行駛車輛的側(cè)力不再適當?shù)胤峙湓谝粋€或者更多輪上，車輛就會失穩(wěn)，尤其是車輛沿曲線行駛時。駕駛員感覺到的“搖擺”起初是轉(zhuǎn)彎或者與車的軸線形成一個紡錘形時。必須有一個獨立的傳感器能夠識別這個“紡錘”，因為ABS防抱死系統(tǒng)和牽引控制系統(tǒng)通過車輪的轉(zhuǎn)速不能檢測車輛的橫向運動。</p><p><b>　　轉(zhuǎn)向操作</

17、b></p><p>　　該系統(tǒng)檢測微小的汽車不足轉(zhuǎn)向（當車輛對于方向盤操作反應(yīng)遲緩）和方向盤的“過敏”反應(yīng)（后輪發(fā)生來回擺動）。當車輛在轉(zhuǎn)向時如果發(fā)生不足轉(zhuǎn)向和過度轉(zhuǎn)向運動時，穩(wěn)定調(diào)節(jié)系統(tǒng)能夠通過后輪進行內(nèi)部制動（針對曲線）糾正錯誤。這種情況是駕駛員不能感覺類似于ABS防抱死系統(tǒng)接近于抱死極限，而使車輛不失去控制。穩(wěn)定調(diào)節(jié)系統(tǒng)能夠通過發(fā)動機降速或者單輪制動來減小推動力。</p><p&

18、gt;　　博世公司的研究員解釋說：“側(cè)面偏離角度表明此時車輛的偏航靈敏性，并反映為轉(zhuǎn)向角度，轉(zhuǎn)向角度隨著車輛偏離角度的增大而減小。一旦偏離角度超過某一限度，駕駛員就很難重新進行操作。在干燥的路面偏離角度不能夠超過10度，而在積雪路面上極限偏離角度為4度。</p><p>　　多數(shù)司機都沒有從制動中恢復行駛的經(jīng)驗。他們不知道輪胎和地面之間的摩擦系數(shù)，更不知道他們的車的側(cè)緣穩(wěn)定邊界。當極限被沖破時，駕駛員通常會很緊張

19、以至于做出錯誤的反應(yīng)。ITT的格雷柏解釋說：“過度轉(zhuǎn)向引起車輛擺尾，使汽車更快的失控。ASMS傳感器能夠快速的檢測到制動開始時各個車輪的活動情況，從而使車輛恢復到穩(wěn)定行駛軌道。</p><p>　　對于穩(wěn)定調(diào)節(jié)系統(tǒng)界面的可操作性是很重要的，這樣可以預(yù)示帶有穩(wěn)定系統(tǒng)的駕駛和普通駕駛給人的感覺沒有什么區(qū)別。</p><p>　　穩(wěn)定系統(tǒng)最大的優(yōu)點在于反應(yīng)速度，它不僅可以對制動作出快速反應(yīng)，還可

20、以對車輛狀況（例如車重變化，輪胎磨損），路面質(zhì)量作出快速反應(yīng)統(tǒng)，因此能夠通過改變側(cè)面受力平橫處理，達到最好的駕駛穩(wěn)定性。</p><p>　　穩(wěn)定系統(tǒng)識別駕駛員想達到的（理想路線）和車輛實際行駛路線（實際路線）的不同，目前的汽車需要一套高效的傳感器和一臺高效處理信息的處理器。</p><p>　　博世公司的VDC/ESP電子控制單元是一個由兩個48兆的ROM組成的傳統(tǒng)實驗電路板。范桑特說：

21、“48KB的內(nèi)存容量是用以完成設(shè)計任務(wù)的‘智能’的基本要求”。他在SAE中指出。ABS防抱死系統(tǒng)是獨立的，只提供四分之一的這樣的容量，而ABS和牽引控制系統(tǒng)組合在一起的容量只有這個軟件容量的一半。</p><p>　　除了ABS防抱死系統(tǒng)和牽引控制系統(tǒng)所具有的關(guān)系傳感器外，VDC/ESP運用了偏航比率傳感器，橫向加速度傳感器，轉(zhuǎn)向角傳感器，制動壓力傳感器來獲取汽車的加速，搖擺或者剎車的信息。系統(tǒng)通過汽車網(wǎng)關(guān)獲得所

22、需的通常的路面信息。方向盤上的傳感器由一組安裝在方向盤上的發(fā)光二極管和光敏二極管組成。一只硅壓力傳感器通過控制前輪剎車內(nèi)壓力油的壓力控制制動壓力（因為制車壓力來源于駕駛員）。</p><p>　　確定車輛實際的行駛路線是一項非常復雜的工作。通過縱向滑動車輪速度傳感器提供給反向制動或者牽引控制系統(tǒng)的車輪轉(zhuǎn)速信號，以便系統(tǒng)對可能發(fā)生的動作作出精確的分析。同時側(cè)向難預(yù)料的運動分析是必須的，所以系統(tǒng)必須再拓展兩個額外的傳

23、感器---偏航比率傳感器和側(cè)向加速度傳感器。</p><p>　　橫向加速度表檢測沿曲線行駛時所帶來的受力狀況。這種類似的傳感器通過一臺直線霍爾發(fā)電機把彈簧的直線運動轉(zhuǎn)變成電信號來實現(xiàn)對彈簧機構(gòu)的控制。這種傳感器必須很靈敏，它的控制角為±1.4g。</p><p><b>　　偏航比率回轉(zhuǎn)儀</b></p><p>　　最新的穩(wěn)定調(diào)節(jié)

24、系統(tǒng)的核心在于類似于陀螺儀的偏航比率回轉(zhuǎn)儀。傳感器測量車輛對豎直軸的旋轉(zhuǎn)。這個測量原理來源于航空工業(yè)，并且被博施公司大規(guī)模的應(yīng)用于汽車工業(yè)?，F(xiàn)有的回轉(zhuǎn)儀市場提供兩種選擇，一種是應(yīng)用與航空航天業(yè)的價值6000美元（由位于英國羅徹斯特的美國通用電器公司航空股份有限公司提供），另一種是用于照相機的價值160美元。由SAE報得知博施公司采取一種圓柱形設(shè)計方案以實現(xiàn)低成本下的高性能。這種傳感器需要一項更大的投資以應(yīng)對汽車所處的極端環(huán)境狀態(tài)。同時偏

25、航比率回轉(zhuǎn)儀的價格必須降低，這樣才能充分應(yīng)用與汽車。</p><p>　　偏航比率回轉(zhuǎn)儀有一個復雜的內(nèi)部結(jié)構(gòu)，其內(nèi)部是有一個很小的圓柱形鋼管伺服測量元件。圓柱的薄壁上有壓電元件能夠在15千赫茲的頻率下震動。四對這樣的感應(yīng)器安放在圓柱體的周圍，一對元件的位置與另一對的位置相對。其中的一對通過應(yīng)用正弦電壓引起柱體在其固有頻率下產(chǎn)生共振，并將振動傳送給變頻器。在每一對傳感器之間，振顫節(jié)點繞著汽車的垂直軸作細微的運動。這

26、時如果沒有偏航輸入，震動曲線就是一條穩(wěn)定的曲線。如果有信號輸入，節(jié)點的位置和曲線的波谷就會在相對的防線繞著圓筒壁做旋轉(zhuǎn)運動（科里奧利加速度）。這個輕微的位移就會成為汽車偏航比率的度量標準。</p><p>　　許多司機都相互宣稱他們的車輛在光滑轉(zhuǎn)彎處，車尾部將要被甩出去的時候，新系統(tǒng)會把車輛“推”回到正確的軌跡上方面的經(jīng)驗。 </p><p>　　許多觀察員指出，穩(wěn)定調(diào)節(jié)系統(tǒng)可能會使司機在

27、較低摩擦力的路面上過分自信，盡管他們占少數(shù)?；蛟S需要指導司機如何恰當?shù)氖褂密囕v穩(wěn)定調(diào)節(jié)系統(tǒng)，就像當初讓司機學習不能向防抱死制動系統(tǒng)里泵油一樣。</p><p>　　雖然只介紹了很少的關(guān)于為未來汽車研制的新一代主動安全系統(tǒng)（遠遠超過了雷達掃描儀類似的系統(tǒng)），但避免交通事故仍然是汽車安全工程的主題。美國國際電信公司負責人指出“當穩(wěn)定調(diào)節(jié)技術(shù)伴隨著汽車結(jié)構(gòu)全面性能穩(wěn)步提高的時候，多數(shù)可避免的事故將不再發(fā)生了”。新一代的

28、安全系統(tǒng)也會起到同樣的效果。</p><p>　　學 生：孔祥龍 簽字： 年 月 日</p><p>　　指導教師：唐 嵐 簽字： 年 月 日</p><p>　　Spin control for cars</p><p>　　

29、Stability control systems are the latest in a string of technologies focusing on improved driving safety. Such systems detect the initial phases of a skid and restore directional control in 40 milliseconds, seven times f

30、aster than the reaction time of the average human. They correct vehicle paths by adjusting engine torque or applying the left- or-right-side brakes, or both, as needed. The technology has already been applied to the Merc

31、edes-Benz S600 coupe.</p><p>　　Automatic stability systems can detect the onset of a skid and bring a fishtailing vehicle back on course even before its driver can react. </p><p>　　Safety glass,

32、 seat belts, crumples zones, air bags, antilock brakes, traction control, and now stability control. The continuing progression of safety systems for cars has yielded yet another device designed to keep occupants from in

33、jury. Stability control systems help drivers recover from uncontrolled skids in curves, thus avoiding spinouts and accidents. </p><p>　　Using computers and an array of sensors, a stability control system det

34、ects the onset of a skid and restores directional control more quickly than a human driver can. Every microsecond, the system takes a "snapshot," calculating whether a car is going exactly in the direction it i

35、s being steered. If there is the slightest difference between where the driver is steering and where the vehicle is going, the system corrects its path in a split-second by adjusting engine torque and/or applying the ca&

36、lt;/p><p>　　A stability control system senses the driver's desired motion from the steering angle, the accelerator pedal position, and the brake pressure while determining the vehicle's actual motion fr

37、om the yaw rate (vehicle rotation about its vertical axis) and lateral acceleration, explained Anton van Zanten, project leader of the Robert Bosch engineering team. Van Zanten's group and a team of engineers from Me

38、rcedes-Benz, led by project manager Armin Muller, developed the first fully effective stabilit</p><p>　　Automotive safety experts believe that stability control systems will reduce the number of accidents, o

39、r at least the severity of damage. Safety statistics say that most of the deadly accidents in which a single car spins out (accounting for four percent of all deadly collisions) could be avoided using the new technology.

40、 The additional cost of the new systems is on the order of the increasingly popular antilock brake/traction control units now available for cars. </p><p>　　The debut of stability control technology took plac

41、e in Europe on the Mercedes-Benz S600 coupe this spring. Developed jointly during the past few years by Robert Bosch GmbH and Mercedes-Benz AG, both of Stuttgart, Germany, Vehicle Dynamics Control (VDC). in Bosch termino

42、logy, or the Electronic Stability Program (ESP), as Mercedes calls it, maintains vehicle stability in most driving situations. Bosch developed the system, and Mercedes-Benz integrated it into the vehicle. Mercedes engine

43、ers used </p><p>　　Stability control systems will first appear in mid-1995 on some European S-Class models and will reach the U.S. market during the 1996 model year (November 1995 introduction). It will be a

44、vailable as a $750 option on Mercedes models with V8 engines, the following year it will be a $2400 option on six-cylinder system. And $1650 of the latter price is for the traction control system, a prerequisite for stab

45、ility control.</p><p>　　Bosch is not alone in developing such a safety system. ITT Automotive of Auburn Hills, Mich., introduced its Automotive Stability Management System (ASMS) in January at the 1995 North

46、 American International Auto Show in Detroit. "ASMS is a quantum leap in the evolution of antilock brake systems, combining the best attributes of ABS and traction control into a total vehicle dynamics management sy

47、stem," said Timothy D. Leuliette, ITT Automotive's president and chief executive officer. </p><p>　　"ASMS monitors what the vehicle controls indicate should be happening, compares that to what

48、is actually happening, then works to compensate for the difference," said Johannes Graber, ASMS program manager at ITT Automotive Europe. ITT's system should begin appearing on vehicles worldwide near the end of

49、 the decade, according to Tom Mathues, director of engineering of Brake & Chassis Systems at ITT Automotive North America. Company engineers are now adapting the system to specific car models from</p><p>

50、;　　A less-sophisticated and less-effective Bosch stability control system already appears on the 1995 750iL and 850Ci V-12 models from Munich-based BMW AG. The BMW Dynamic Stability Control (DSC) system uses the same whe

51、el-speed sensors as traction control and standard anti-lock brake (ABS) systems to recognize conditions that can destabilize a vehicle in curves and corners. To detect such potentially dangerous cornering situations, DSC

52、 measures differences in rotational speed between the two front</p><p>　　The new Bosch and ITT Automotive stability control systems benefit from advanced technology developed for the aerospace industry. Just

53、 as in a supersonic fighter, the automotive stability control units use a sensor-based computer system to mediate between the human controller and the environment - in this case, the interface between tire and road. In a

54、ddition, the system is built around a gyroscope like sensor design used for missile guidance. </p><p>　　BEYOND ABS AND TRACTION CONTROL:</p><p>　　Stability control is the logical extension of AB

55、S and traction control, according to a Society of Automotive Engineers paper written by van Zanten and Bosch colleagues Rainer Erhardt and Georg Pfaff. Whereas ABS intervenes when wheel lock is imminent during braking, a

56、nd traction control prevents wheel slippage when accelerating, stability control operates independently of the driver's actions even when the car is free-rolling. Depending on the particular driving situation, the sy

57、stem may activat</p><p>　　The idea behind the three active safety systems is the same: One wheel locking or slipping significantly decreases directional stability or makes steering a vehicle more difficult.

58、If a car must brake on a low-friction surface, locking its wheels should be avoided to maintain stability and steer ability. </p><p>　　Whereas ABS and traction control prevent undesired longitudinal slip, st

59、ability control reduces loss of lateral stability. If the lateral forces of a moving vehicle are no longer adequate at one or more wheels, the vehicle may lose stability, particularly in curves. What the drive “fishtaili

60、ng" is primarily a turning or spinning around the vehicle's axis. A separate sensor must recognize this spinning, because unlike ABS and traction control, a car's lateral movement cannot be calculated from i

61、t</p><p>　　SPIN HANDLERS:</p><p>　　The new systems measure any tendency toward understeer (when a car responds slowly to steering changes), or over-steer (when the rear wheels try to swing aroun

62、d). If a car understeers and swerves off course when driven in a curve, the stability control system will correct the error by breaking the inner (with respect to the curve) rear wheel. This enables the driver, as in the

63、 case of ABS, to approach the locking limit of the road-tire interface without losing control of the vehicle. The stabili</p><p>　　The influence of side slip angle on maneuverability, the Bosch researchers e

64、xplained, shows that the sensitivity of the yaw moment on the vehicle, with respect to changes in the steering angle, decreases rapidly as the slip angle of the vehicle increases. Once the slip angle grows beyond a certa

65、in limit, the driver has a much harder time recovering by steering. On dry surfaces, maneuverability is lost at slip-angle values larger than approximately 10 degrees, and on packed snow at approximately </p><

66、p>　　Most drivers have little experience recovering from skids. They aren't aware of the coefficient of friction between the tires and the road and have no idea of their vehicle's lateral stability margin. When

67、 the limit of adhesion is reached, the driver is usually caught by surprise and very often reacts in the wrong way, steering too much. Over steering, ITT's Graber explained causes the car to fishtail, throwing the ve

68、hicle even further out of control. ASMS sensors, he said, can quickly detect th</p><p>　　It is important that stability control systems be user-friendly at the limit of adhesion - that is, to act predictably

69、 in a way similar to normal driving. </p><p>　　The biggest advantage of stability control is its speed - it can respond immediately not only to skids but also to shifting vehicle conditions (such as changes

70、in weight or tire wear) and road quality. Thus, the systems achieve optimum driving stability by changing the lateral stabilizing forces. </p><p>　　For a stability control system to recognize the difference

71、between what the driver wants (desired course) and the actual movement of the vehicle (actual course), current cars require an efficient set of sensors and a greater computer capacity for processing information. </p&g

72、t;<p>　　The Bosch VDC/ESP electronic control unit contains a conventional circuit board with two partly redundant microcontrollers using 48 kilobytes of ROM each. The 48-kB memory capacity is representative of the

73、 large amount of "intelligence" required to perform the design task, van Zanten said. ABS alone, he wrote in the SAE paper, would require one-quarter of this capacity, while ABS and traction control together re

74、quire only one half of this software capacity. </p><p>　　In addition to ABS and traction control systems and related sensors, VDC/ESP uses sensors for yaw rate, lateral acceleration, steering angle, and brak

75、ing pressure as well as information on whether the car is accelerating, freely rolling, or braking. It obtains the necessary information on the current load condition of the engine from the engine controller. The steerin

76、g-wheel angle sensor is based on a set of LED and photodiodes mounted in the steering wheel. A silicon-micro machine pressure sens</p><p>　　Determining the actual course of the vehicle is a more complicated

77、task. Wheel speed signals, which are provided for antilock brakes/traction control by inductive wheel speed sensors, are required to derive longitudinal slip. For an exact analysis of possible movement, however, variable

78、s describing lateral motion are needed, so the system must be expanded with two additional sensors - yaw rate sensors and lateral acceleration sensors. </p><p>　　A lateral accelerometer monitors the forces o

79、ccurring in curves. This analog sensor operates according to a damped spring-mass mechanism, by which a linear Hall generator transforms the spring displacement into an electrical signal. The sensor must be very sensitiv

80、e, with an operating range of plus or minus 1.4 g. </p><p>　　YAW RATE GYRO:</p><p>　　At the heart of the latest stability control system type is the yaw rate sensor, which is similar in function

81、 to a gyroscope. The sensor measures the speed at which the car rotates about its vertical axis. This measuring principle originated in the aviation industry and was further developed by Bosch for large-scale vehicle pro

82、duction. The existing gyro market offers two widely different categories of devices: $6000 units for aerospace and navigation systems (supplied by firms such as GEC Marcon</p><p>　　The yaw rate sensor has a

83、complex internal structure centered around a small hollow steel cylinder that serves as the measuring element. The thin wall of the cylinder is excited with piezoelectric elements that vibrate at a frequency of 15 kilohe

84、rtz. Four pairs of these piezo elements are arranged on the circumference of the cylinder, with paired elements positioned opposite each other. One of these pairs brings the open cylinder into resonance vibration by appl

85、ying a sinusoidal voltage at its n</p><p>　　Several drivers who have had hands-on experience with the new systems in slippery cornering conditions speak of their cars being suddenly nudged back onto the righ

86、t track just before it seems that their back ends might break away. </p><p>　　Some observers warn that stability controls might lure some drivers into overconfidence in low-friction driving situations, thoug

87、h they are in the minority. It may, however, be necessary to instruct drivers as to how to use the new capability properly. Recall that drivers had to learn not to "pump" antilock brake systems. </p><

88、;p>　　Although little detail has been reported regarding next-generation active safety systems for future cars (beyond various types of costly radar proximity scanners and other similar systems), it is clear that accid

89、ent-avoidance is the theme for automotive safety engineers. "The most survivable accident is the one that never happens," said ITT's Graber. "Stability control technology dovetails nicely with the trem