外文翻譯----非線性pid控制在一系列卡車abs問題中的應用

1、<p>　　An Application of Nonlinear PID Control to a Class of Truck ABS Problems</p><p>　　Fangjun Jiang</p><p>　　Ford Motor Company, Product Development Center, GB-E65, MD</p><p>

2、;　　19920901 Oakwood Blvd. Dearborn, MI 48124</p><p>　　Zhiqiang Gao</p><p>　　The Applied Control Research LaboratoryDepartment of </p><p>　　Electrical and Computer Engineering</p&

3、gt;<p>　　Cleveland State University, Cleveland, Oh 44115</p><p>　　Abstract: A new NPID (Nonlinear Proportional-Integral-Differential) control algorithm is applied to a class of truck ABS (Anti-lock Br

4、ake System) problems. The NPID algorithm combines the advantages of robust control and easy tuning. Simulation results at various situations using TruckSim show that NPID controller has shorter stopping distance and bett

5、er velocity performance than the conventional PID controller and a loop-shaping controller.</p><p>　　Keywords: Nonlinear, PID, ABS.</p><p>　　1. Introduction</p><p>　　ABS for commerc

6、ial vehicles appeared on the market in 1960s and began to grow fast in 1970s with the technologies of microcomputers and electronics [1]. ABS is recognized as an important contribution to road safety. It is now available

7、 in almost all types of vehicles. The automotive industry is continuously developing new generations of ABS. The technologies of ABS are also applied in TCS (Traction Control System) and VDSC (Vehicle Dynamic Stability C

8、ontrol) It is well known that wheels will sli</p><p>　　The wheel slip is defined as:</p><p><b>　?。?.1）</b></p><p>　　where S, ω, R and V denote the wheel slip, the wheel

9、angular velocity, the wheel rolling radius, and the vehicle forward velocity, respectively.</p><p>　　In normal driving conditions, V ≈ ωR therefore S ≈ 0. In severe braking, it is common to have ω = 0 while

10、 V ≠ 0 , or S = 1, which is called wheel lockup. Wheel lockup is undesirable since it prolongs the stopping distance and causes the loss of direction control.</p><p>　　1.1 A Class of Truck ABS Problems</p

11、><p>　　The objective of ABS is to manipulate the wheel slip so that a maximum friction force is obtained and the steering stability (also known as the lateral stability) is maintained. That is, to make the vehi

12、cle stop in the shortest distance possible while maintaining the directional control. It is well known that the friction coefficient, μ, is a nonlinear function of the slip, S. The ideal goal for the control design is to

13、 regulate the wheel velocity, ω, such that an optimal slip, which corresponds</p><p>　　In this paper, the control design is focused on a class of truck ABS problems, which pose a few unique challenges, diffe

14、rent from passenger cars.</p><p>　　1. The actuator of the truck ABS is a pneumatic brake system, which is typically slower in response and harder to control than a hydraulic brake system. The control action

15、of the brake system is discrete. The brake pressure is controlled by discrete valves (open or close). The brake pressure can be controlled to increase, hold constant or decrease. Through PWM (Pulse Width Modulation), the

16、 actions of the discrete valves are mapped into a continues analog control signal ranging from –1 to +1, whe</p><p>　　pressure and 0 means holding pressure as constant.</p><p>　　2. The measureme

17、nt of the brake pressure is not available, which makes the control of the pneumatic brake system even more difficult. The ABS controller must deal with the brake dynamics and the wheel dynamics as a whole plant.</p>

18、;<p>　　3. The measurement of the vehicle velocity or vehicle acceleration is not available. The only feedback signals are two or four channels of wheel angular velocity. It poses a challenging problem for the vehi

19、cle velocity estimation since the vehicle velocity is necessary to set the wheel reference velocity. A separate study was carried out to resolve this issue in [2].</p><p>　　4. The complex dynamics of the tra

20、ctor/trailer system and the large variations of the truck operation condition set a very stringent requirement for the ABS controller. The tuning and testing of a truck ABS are also much more difficult than an ABS for pa

21、ssenger cars.</p><p>　　1.2 Current Technology</p><p>　　Various control strategies have been implemented in real ABS products or discussed in publications. Since the technologies used in commerci

22、al ABS products are usually kept as trade secrets, it is very difficult to determine their detailed control algorithms. From the literature available [3, 4, 5, 6], a few algorithms use an approach similar to "bang-b

23、ang" control. They usually have two or more threshold values for the wheel deceleration or the wheel slip. Once the calculated wheel deceleration </p><p>　　Finite state machine methods are also widely a

24、pplied in the industry. Based upon the measured signals such s wheel velocity, vehicle deceleration and/or brake pressure, the operation of the vehicle is characterized by a set of different states, such as normal drivin

25、g, lockup, free rolling ,etc. The rake pressure is then controlled to increase, hold constant or decrease based on the state the vehicle is in and other design logic.</p><p>　　These two methods heavily rely

26、on the experience of the designers and drivers. It is fairly difficult to analyze the controller’s performance during the design stage. The tuning of the controller is done purely on trial and error basis. The needs for

27、a systematic design approach for the development are quite evident in this industry. Such needs motivated the research efforts that result in [9].</p><p>　　In particular, the truck ABS problems are reformula

28、ted as a closed-loop control problem. A cascade loop structure, as shown in Figure 1, as well as various control algorithms are proposed. The outer loop, which includes the vehicle velocity estimation and desired slip ca

29、lculation, provides the command signal, Vwd , for the inner wheel velocity loop. The separation of the outer and inner loop designs, similar to the separation principle in linear system theory, are only made possible in

30、the frame</p><p>　　Figure 1: A Cascade Structure for ABS</p><p>　　The vehicle velocity estimation and the wheel velocity controller are the key design issues. A nonlinear filter approach, based

31、on the work in [10], to vehicle velocity estimation problems was developed and proved to be quite effective [2,9]. For inner loop control, three methods were explored in [9], including the PID, the loop-shaping, and the

32、NPID algorithms. The PID is easy to design and tune but is also limited in performance. The loop-shaping controller, designed based on the linear model </p><p>　　Similar tuning difficulties can also be seen

33、in various other advanced control strategies such as fuzzy logic control, model reference control and neural network, which were also extensively discussed as possible candidates for ABS.</p><p>　　In the dev

34、elopment of an ABS controller, one of the major issues is testing. The ABS controller needs to go through a series of software and hardware tests. Due to the complexity of the truck system and the large variations of ope

35、ration conditions, on-site calibration or tuning of the controller is necessary. This requires the new control methods to be not only more powerful, but also easily tunable. The tuning of a fuzzy logic controller or mode

36、l reference controller involves multiple rules or </p><p>　　Based on the above discussion, we propose a NPID control design strategy, based on the work of J. Han [11,12], that combines the advantages of robu

37、st performance and the ease of tuning. It is proved to be an effective controller for truck ABS.</p><p><b>　　英語翻譯</b></p><p>　　· 非線性PID控制在一系列卡車ABS問題中的應用</p><

38、p><b>　　蔣方軍</b></p><p>　　福特汽車公司產(chǎn)品開發(fā)中心，GB-E65,MD 19920901</p><p>　　OAKWOOD BLVD.DEARBORN,MI 48124</p><p><b>　　高志強</b></p><p>　　克利夫蘭州立大學電子與計算機工程

39、應用控制</p><p>　　研究實驗室，克利夫蘭，OH44115</p><p>　　摘要：一種新型的NPID（非線性比例-積分-微分）控制算法正應用于一系列卡車的ABS（制動防抱死系統(tǒng)）問題中。NPID算法不僅魯棒性強，而且參數(shù)便于整定。使用仿真軟件TRUCKSIM在各種情況下的仿真結果顯示，相對于常規(guī)的PID控制器和回路整形控制器，NPID控制器具有更短的制動距離和更好的速度表現(xiàn)性。

40、</p><p>　　關鍵詞：非線性，PID,ABS.</p><p><b>　　1.引言</b></p><p>　　商用車上配置ABS系統(tǒng)出現(xiàn)于上世紀60年代，隨著微型計算機和電子技術的發(fā)展，ABS系統(tǒng)在70年代進入了一個高速發(fā)展的時期。ABS對于公路交通安全做出了巨大貢獻，幾乎所有的汽車都配備了ABS系統(tǒng)。汽車工業(yè)也正在不斷的開發(fā)更新一

41、代的ABS系統(tǒng)，同時ABS技術也正被應用于TCS(牽引控制系統(tǒng))和VDSC（車輛動態(tài)穩(wěn)定性控制系統(tǒng)）。</p><p>　　眾所周知，車輛在緊急制動或在一些濕滑、結冰的路面上制動時，車輪將會滑動并鎖死。這通常會導致一個較長的制動距離，某些時候汽車還將喪失轉向穩(wěn)定性。ABS的功能就是在汽車制動時防止車輪鎖死，在保持較好的轉向穩(wěn)定性的同時獲得最短的制動距離。</p><p>　　車輪滑移率為：

42、 （1.1）</p><p>　　式中S,w,R和V分別代表車輪的滑移率、角速度、滾動半徑和車輛前進速度。在正常的駕駛狀態(tài)下，V≈wR,因此S≈0。在緊急制動的情況下，w=0而V≠0,即S=1,這種情況稱為車輪鎖死。我們不期望車輪鎖死的情況發(fā)生，因為它延長了停車距離并將導致轉向控制作用的喪失。</p><p>　　1.1 卡車AB

43、S的一系列問題</p><p>　　ABS的目標是通過控制車輪滑移率以獲得最大的摩擦力，并且能夠維持轉向穩(wěn)定性，以使汽車在盡可能短的距離內(nèi)停車，同時維持轉向控制。大家知道，摩擦系數(shù)是滑移率S的非線性函數(shù)，控制器設計的理想目標是通過調(diào)節(jié)車輪轉速w得到與最大摩擦力相對應的最優(yōu)滑移率。為簡化起見，工業(yè)上通常設定期望滑移率為0.2.給定汽車速度V和車輪半徑R,ABS控制問題就轉化成為通過調(diào)節(jié)車輪轉速w以使得（1.1）式中

44、的滑移率S達到期望值0.2.</p><p>　　本文中設計的控制器主要是針對卡車的ABS問題，這類問題不同于小型汽車，具有一定的特殊性。</p><p>　　（1）卡車ABS執(zhí)行器通常是氣動系統(tǒng)，這類系統(tǒng)比液壓制動系統(tǒng)響應更慢，更難以控制。制動壓力的控制是通過離心閥的開啟與關閉來完成的，受控的制動壓力可以增大、保持或減小。通過PWM（脈寬調(diào)制），離心閥的輸出可以用一個連續(xù)的模擬控制信號描

45、述，其取值范圍在-1～+1之間，-1表示完全卸除壓力，+1表示施加最大壓力，0表示將壓力維持在一個恒定的數(shù)值。</p><p>　?。?）制動壓力的檢測通常是不能實現(xiàn)的，這將使得氣動制動系統(tǒng)的控制更加困難。ABS控制器必須將制動動態(tài)過程和車輪動態(tài)過程看做一個整體的被控對象來處理。</p><p>　?。?）汽車速度或加速度的測量也不能實現(xiàn)，僅有的反饋信號是兩路或四路車輪的角速度。估算汽車速

46、度將是一個具有挑戰(zhàn)性的問題，因為汽車速度對于設定車輪參考轉速非常必要。一項解決這種問題的獨立研究已經(jīng)實現(xiàn)。</p><p>　?。?）拖動系統(tǒng)復雜的動態(tài)過程和卡車工作條件的多變性對ABS控制器提出了十分苛刻的要求?？ㄜ嘇BS系統(tǒng)整定與調(diào)試過程比小汽車的相應過程更加困難。</p><p><b>　　1.2 技術現(xiàn)狀</b></p><p>　

47、　在實際的ABS產(chǎn)品中使用了各種各樣的控制策略，很多的著作論文中也談到了這些控制策略。由于商業(yè)ABS產(chǎn)品所使用的技術通常作為行業(yè)秘密，很難搞清這些產(chǎn)品的詳細控制算法。從已有的參考文獻可以看出，一部分算法使用的方法類似于“棒-棒”控制。對于車輪的減速或滑移率，這些算法通常設定兩個或兩個以上的極限值，制動壓力受控于增加、保持或減少狀態(tài)。這些算法將會在-S曲線上導致峰值搜尋策略，或者強迫車輪的減速/滑移率在一個特定的范圍內(nèi)。</p>

48、;<p>　　有限狀態(tài)機構法在工業(yè)中被廣泛應用?；谥T如車輪轉速、車輛減速或制動壓力這些被測信號，車輛的操控以一系列不同的狀態(tài)為特征，如正常駕駛、鎖死和空擋滑行?；谲囕v所處的狀態(tài)和其他的控制邏輯，受控的制動壓力可以增大、保持或減小。</p><p>　　這兩種方法在很大程度上依賴于設計者和駕駛者的經(jīng)驗。在設計階段，分析控制器的性能是非常困難的，控制器參數(shù)的整定完全是以試湊法為基礎的。</p&

49、gt;<p>　　實際上，卡車ABS問題可以歸咎為一個閉環(huán)控制問題。正如各種各樣的控制算法所提出的一樣，它是一個串級回環(huán)結構，如圖1所示。外環(huán)包括車輛速度估算和期望滑移率計算，為內(nèi)環(huán)車輪轉速提供了命令信號。將系統(tǒng)分為外環(huán)和內(nèi)環(huán)的設計方法與線性系統(tǒng)的分割原理類似，只適用于框圖化的理論分析。</p><p>　　圖1..ABS的串級結構</p><p>　　車輪速度估算與車輪速度

50、控制器是設計的關鍵?；谖墨I【10】的工作所開發(fā)出的一種非線性濾波器方法對于車輛的速度估算是十分有效的。對于內(nèi)環(huán)控制，文獻【9】提供了三種方法，分別是PID算法、回路整形算法和NPID算法。PID算法容易設計、便于整定，但性能上受約束；基于被控對象和所設計的回路整形控制器的回路整形算法，在仿真時功能較為強大，但在真正的工業(yè)仿真器上，這樣的控制器難以整定，因為控制器調(diào)整時必須面對模型中為數(shù)眾多的非線性和干擾因素。</p>&

51、lt;p>　　相似的整定困難問題也出現(xiàn)在了各種各樣的先進的控制策略中，如模糊邏輯、參考模型和神經(jīng)網(wǎng)絡控制算法等，這些都曾作為ABS系統(tǒng)的控制算法在很多文獻中都有討論。</p><p>　　ABS控制器開發(fā)面臨的一個主要問題是測試的問題，它需要通過一系列的軟硬件測試。由于卡車系統(tǒng)的復雜性和工作環(huán)境的多變性，需要現(xiàn)場的控制器校準或整定，這就要求新的控制方案不僅要功能強大，而且便于整定。模糊邏輯控制器和參考模型控