【機械類畢業(yè)論文中英文對照文獻翻譯】利用只裝有車輪速度傳感器的制動防抱死系統(tǒng)做路面情況鑒定,機械類畢業(yè)論文中英文對照文獻翻譯,機械類,畢業(yè)論文,中英文,對照,對比,比照,文獻,翻譯,利用,應用,裝有,車輪,速度,傳感器,制動,抱死,系統(tǒng),路面,情況,鑒定 ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ 裝 ┊ ┊ ┊ ┊ ┊ 訂 ┊ ┊ ┊ ┊ ┊ 線 ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ ┊ 畢業(yè)設計（論文）報告紙 利用只裝有車輪速度傳感器的制動 防抱死系統(tǒng)做路面情況鑒定 摘要： 制動防抱死系統(tǒng)(ABS),是目前在汽車上得到廣泛使用的設備。 為了降低制造成本，并利用現(xiàn)有可用的技術，標準ABS系統(tǒng)僅使用車輪速度傳感器檢測車輪轉速,這是不能夠直接獲取控制單元需要的車輪滑移率，但可以利用計算所得的車輪角速度和估計的車速間的關系來計算參考滑移率。因此，道路摩擦系數(shù),它決定了車輛在緊急剎車時的減速度, 是一個估算汽車速度的重要參數(shù)。本文分析了在不同路面情況下模擬緊急制動時車輪的加速度，并選擇一對特殊的點來確定車輪加速曲線在每個不同的操縱情況下，比如路面情況,制動扭矩和車輪的垂直載荷。它是建立在每個用試點做出的針對不同路面的曲線明顯不同于其他路面。 因此，不同的路面可以用這些點來區(qū)分，這些點反映了他們所代表的路面情況。分析假設只有車輪速度傳感器是可利用的儀器并且道路附著情況可以在緊急制動的開始初期階段確定。 關鍵字： 制動防抱死系統(tǒng)(ABS)；路面情況鑒定； 車輪角加速； 輪胎特性 介紹 對制動防抱死系統(tǒng)(ABS)來說，道路附著情況是最重要的因素之一。 標準ABS系統(tǒng)可以在制動時確定道路附著情況，并且確定道路摩擦力是高 (瀝青路面)、或低(雪、冰路面)，然后由控制單元激活相應的邏輯控制系統(tǒng)。 只有車輪速度傳感器在標準ABS系統(tǒng)中可以確定路面情況，不需要其他需要傳感器的幫助。 道路情況鑒定是當前汽車控制研究領域的一個熱門主題，但研究人員通常采用額外的除車輪速度傳感器以外的可用的設備來測量汽車運動及其他國家參數(shù)來持續(xù)監(jiān)測道路狀況。但是標準ABS系統(tǒng)只需要在制動初期階段確定道路狀況，并獲得路面信息，以確定其控制單元的必需操作。 顯然，標準ABS系統(tǒng)不要求太精確的鑒定，因此只需要較少的儀器和費用。但是，這種道路情況鑒定方法并不明確。 本文正是研究在標準ABS系統(tǒng)下的道路情況鑒定方法。 分析的依據(jù)是通過測量車輪角速度所得的車輪角加速度。 因為輪胎與路面在不同路面上的磨擦特性不同，所以,，在不同道路表面上車輪制動時的反應也不同，因此車輪制動反應研究必須包括路面附著信息。所以我們模擬車輪制動情況，并在車輪加速曲線上選擇兩個典型數(shù)據(jù)作為標準來區(qū)分不同的路面。并討論了測量中的不確定因素的影響。 1建模 四分之一的汽車模型(表1)使用的是Dugoff輪胎模型。輪胎滑動摩擦力的最大值 (即附著系數(shù))對不同的路面是不同的，如干燥瀝青路面0.8-0.9，濕瀝青路面0.5-0.7，積雪路面約0.2%,冰面0.1。此外，當滑移率從零開始增大時，摩擦系數(shù)隨之增加的速度是不同的。特別是在冰雪路面上的摩擦系數(shù)增加速度遠低于在瀝青路面上。在路面摩擦系數(shù)達到最大前控制單元對路面情況作反映之時，這一特點是很重要的。當摩擦系數(shù)接近最大值時，控制單元開始調節(jié)制動壓力。一般而言,摩擦系數(shù)隨著滑移率增加的速度在瀝青路面上至少是在雪或冰路面上的兩倍。 為了反映此差異，在瀝青路面上的曲線的初始階段的斜率應該為雪地路面上的兩倍。如果此差異更大，以此假設得出的結果將會更加可信。 圖一 四分之一汽車模型 一階制動模型為： dTp/dt=(Tp-Tb)/ て (1) 其中TP是施加的制動扭矩,Tb是.實際的制動扭矩，て是制動常量。 2結果和討論 四分之一汽車模型的滿載重量是400公斤。最大的制動扭矩為1000nm，在理論上可以產生足夠的車輛減速度為1g。 在雪地路面上(0.2)，最大的地面制動扭矩是200nm，所以若施加制動扭矩超過200nm，車輪將抱死。在濕瀝青路面上(0.5)，最大的地面制動扭矩是500nm，所以車路將在施加制動扭矩超過500nm時抱死。圖二表示的是在濕瀝青路面(0.5)和雪地路面(0.2)上不同制動扭矩下的車輪減速度曲線。在每種情況下，施加的制動扭矩都高到足以抱死車輪。在任何路面條件下，增加制動扭矩都導致車輪減速度快速增大，并使滑移率增大。 在雪地路面上，當制動扭矩很大時，車輪速度降低比在瀝青路面上更快。因此當?shù)缆飞嫌醒└采w時，該系統(tǒng)可以很容易判斷出。但是，當制動扭矩不是很高但足以引起車輪抱死時，車輪減速的過程就類似于在瀝青面上，控制單元就不能判斷出遇到的是何種路面。這時需要作進一步分析。 ----------------雪地路面 濕瀝青路面 圖二：在瀝青路面和雪地路面上不同制動扭矩下的車輪減速度。 在圖2上的每一條減速度曲線上都可以用兩個點來描述該曲線。第一個是減速度在0.05s時，另一個是減速度達到– 50 rad/s2時。(制動從0時開始) 我們提到的這些是加速度時間曲線確定的標準用這些點做出曲線定義為加速度時間曲線。圖三是最大地面的制動力矩為900,700,500和200時，在瀝青路面(0.9,0.7和0.5)和雪地路面(0.2)上做出的加速時間曲線 。曲線之間沒有相交表明加速度時間曲線確定的標準符合特殊的路面情況或最大的地面制動力矩。 前面的分析是假設的一輛滿載汽車。如果車輪垂直載荷變化，車輪運動情況也會有所不同,所以會產生不同的加速度時間曲線。 圖四中是半載的車輪在瀝青路面(0.9和0.5)和雪地路面(0.5)上做出的三條加速度時間曲線和滿載時的曲線。他們的最大地面制動力矩為450，250和100Nm。 假設一條加速度時間曲線是在車輪局部負荷即在半載和滿載之間在瀝青路面(0.9)上做出的那么它將位于制動力矩為900NM和450NM的曲線之間，那么部分負荷曲線將與制動力矩700nm和500nm的曲線相似。因此，加速度時間曲線的標準不符合的路面情況但符合最大地面制動力矩。 由此可以看出,車輪反映取決于施加的制動扭矩和道路摩擦潛力(地面制動力矩)。如果車輪負載變化并不大，如轎車,滿載的車重不等于空載車重的兩倍，這時在瀝青路面和雪地路面上的加速度時間曲線無論在任何操作情況下都將不會相交。 在這種情況下,可以用加速度時間曲線的標準來分辨出瀝青路面和雪地路面。 圖三：在四中路面情況下的車輪加速度時間曲線 t: 時間 在0.05s時 a: 加速度 在 -50rad/s2 圖四：滿載和半載情況下的車輪加速度時間曲線 t: 時間 在0.05s時 a: 加速度 在 -50rad/s2 3結論 本文分析了車輪加速度與路面情況以及車輪負荷之間的關系。 建議采用的車輪加速時間標準，可以用一個帶有控制單元的車輪速度傳感器來測出?？梢苑从吵鲇陕访媲闆r和車輪負載決定的道路摩擦潛力。對轎車來說,，標準甚至可以確定路面情況，即確定車輪是與瀝青路面還是雪地路面相接觸。 共 頁 第 頁 Road Identification for Anti-Lock Brake Systems Equipped with Only Wheel Speed Sensors Abstract :Anti-lock brake systems (ABS) are now widely used on motor vehicles .To reduce cost and to use currently available technologies ,standard ABS uses only wheel speed sensors to detect wheel angular velocities ,which is not enough to directly obtain wheel slip rations needed by the control unit ,but can be used to calculate reference slip ratios with measured wheel angular velocities and the estimated vehicle speed .Therefore ,the road friction coefficient, which determines the vehicle deceleration during severe braking , is an important parameter in estimating vehicle speed .This paper analyzes wheel acceleration responses in simulations of severe braking on different road surfaces and selects a pair of specific points to identify the wheel acceleration curve for each operating condition ,such as road surface , pedal-braking torque and wheel vertical load .It was found that the curve using the selected points for each road surface clearly differs from that of the other road surface. Therefore, different road surfaces can be distinguished with these selected points which represent their corresponding road surfaces. The analysis assumes that only wheel speed sensors are available as hardware and that the road cohesion condition can be determined in the initial part of the severe braking process. Key words: anti-lock brake systems (ABS); road identification; wheel angular acceleration; tire characteristics Introduction For anti-lock brake systems(ABS),the road cohesion condition is one of the most important factors .Standard ABS can identify road cohesion conditions while braking and decide whether the road friction is high (asphalt) or low (snow , ice),so that the control unit activates the corresponding control logic . Only wheel speed sensors are available in standard ABS to identify the road conditions, with no other sensors needed. Road identification research is currently a popular topic in automotive control, but researchers usually assume extra equipment is available for measuring vehicle motion and other state parameters besides wheel speed sensors, to continuously monitor the road condition. But standard ABS only needs to identify road conditions during the initial braking period, and then obtain road information to ensure necessary operations of the control unit. Obviously, the standard ABS demands less strict identification, therefore less hardware and cost. However, the method to identify the conditions is not obvious. This paper investigates the road identification method for the standard ABS configuration. The analysis is based on the wheel angular acceleration, which is acquired from the measured wheel angular speed. Since tire-road friction characteristics differ on different road surfaces, the wheel responses while braking on different surfaces are also different, so the wheel responses must contain road cohesion information. Therefore, we simulated braking situations and then chose two typical values on the wheel acceleration curve as criteria to distinguish between different road surfaces. Influence of uncertainties in the measurements is also discussed. 1 Modeling A one quarter vehicle model (Fig.1) is used with the Dugoff tire model. The peak values of the tire slip-friction curve (i.e., cohesion coefficient) are different for different road surfaces, such as dry asphalt 0.8-0.9, wet asphalt 0.5-0.7, snow about 0.2 and ice about 0.1.Furthermore, when the slip ratio increases above zero, the friction coefficient increases at a different rate. This is especially true for the increase of the friction coefficients on snow or ice which are much lower than on asphalt. This feature is important since the control unit makes decisions about road conditions before the friction coefficient reaches a maximum .Once the friction coefficient is close to the maximum, the control unit starts to regulate the braking pressure. Generally, the friction coefficient rate of increase with the increasing slip ratio on asphalt is at least double that on snow or ice. To reflect this difference, the initial slope of the characteristic curve on asphalt was assumed to be twice that of snow. If the difference is even greater, the results using the assumption will be even more effective. Fig.1 one quarter vehicle model A first-order braking model is given by: dTp/dt=(Tp-Tb)/ て (1) where Tp is the pedal-braking torque, Tb is the actual braking torque, and てis the brake constant. 2 Results and Discussion Full load for the quarter-vehicle model is 400 kg. The maximum pedal-braking torque is 1000Nm, which is theoretically enough to produce a vehicle deceleration of 1g. On snow (0.2), the maximum ground-braking torque is 200Nm so if the pedal-braking torque is over 200Nm, the wheel will lock. On wet asphalt (0.5), the maximum ground-braking torque is 500Nm so the wheel will lock at a pedal-braking torque higher than 500Nm.Wheel acceleration curves are shown in Fig.2 for braking on wet asphalt (0.5) and snow (0.2) using different pedal-braking torques. In each case, the pedal-braking torque is high enough to lock the wheel. On either road surface, increasing the pedal-braking torque cause the wheel to decelerate more rapidly and the slip ratio to increase. On snow, when the pedal-braking torque is very, the wheel decelerate much more rapidly than on asphalt, so the system can easily judge when the road is covered with snow. However, when the pedal-braking torque is not very high but enough to cause lockup, the wheel deceleration process may resemble that on asphalt, the control unit may not be able to decide which type of road surface has been encountered. This case needs further analysis. ---------- Snow Wet asphalt Fig.2 Wheel acceleration for different pedal braking torques on wet asphalt and snow Each acceleration curve in Fig.2 can be described with two points on the curve. One is the acceleration at the time 0.05s, and the other is the time when the acceleration reaches – 50 rad/s2. (Braking starts at time 0.) We refer to these as the acceleration-time criteria and the curve defined by these points is referred to as the acceleration-time curve. Acceleration-time curves for asphalt (0.9, 0.7, and 0.5) and snow (0.2) are drawn in Fig.3 for maximum ground-braking torques of 900, 700, 500, and 200 Nm. None of the curves intersect which means the acceleration –time criteria corresponds to a particular road surface or maximum ground braking torque. The previous analysis assumed a fully-loaded vehicle. If the wheel vertical load changes, the wheel will behave differently which will result in different acceleration-time curves. Three acceleration-time curves for a half-loaded wheel on asphalt (0.9 and 0.5) and snow (0.5) are shown in Fig.4 with the full-load curves. Their maximum ground braking torque are 450, 250, and 100 Nm. Assuming that the acceleration-time curve for a wheel with a partial load between “full” and “half” on asphalt (0.9) will be located between the curves for braking torque of 900 Nm and 450Nm, then a partial load curve would be similar to the curve for braking torque of 700Nm and 500Nm. Therefore, the acceleration-time criteria do not correspond to the road surface, but to the maximum ground braking torque. It is physically reasonable that the wheel response depends on the difference between the pedal-braking torque and the road friction potential (ground-braking Torque), In cases where the wheel load does not vary greatly, such as in passenger cars, the full load of a car may not be double the load of empty car, then the acceleration-time curves for asphalt and snow will always be separated for any operating conditions. In such cases, asphalt and snow can be distinguished by the acceleration-time criterion. 3 Conclusions This paper analyzes the relationships between the wheel load. The proposed wheel acceleration-time criteria, which can be measured by a control unit with wheel speed sensors, can reflect the road friction potential resulting from the road surface and wheel load. For passenger cars, the criteria can even determine the road conditions, whether the wheel is in contact with asphalt or snow.