資源目錄里展示的全都有預(yù)覽可以查看的噢，，下載就有,,請放心下載，原稿可自行編輯修改=【QQ：11970985 可咨詢交流】====================喜歡就充值下載吧。。。資源目錄里展示的全都有，，下載后全都有,,請放心下載，原稿可自行編輯修改=【QQ：197216396 可咨詢交流】==================== 本科生畢業(yè)論文 姓 名： 學(xué) 號： 學(xué) 院： 機(jī)電工程學(xué)院 專 業(yè)： 機(jī)械工程及自動(dòng)化 論文題目： 汽車ABS系統(tǒng) 指導(dǎo)教師： 職 稱： 副教授  任務(wù)書 學(xué)院 機(jī)電工程學(xué)院 專業(yè)年級 學(xué)生姓名 任務(wù)下達(dá)日期： 畢業(yè)論文日期： 畢業(yè)論文題目：汽車ABS系統(tǒng) 畢業(yè)論文主要內(nèi)容和要求： 本文以轎車為研究對象，展開對汽車ABS的研究。本系統(tǒng)是基于80C196KC單片機(jī)的實(shí)時(shí)控制系統(tǒng)。 本文的基本要求如下: 1.學(xué)會(huì)使用先進(jìn)的文獻(xiàn)檢索工具； 2.了解ABS系統(tǒng)技術(shù)現(xiàn)狀； 3.對基于80C196KC單片機(jī)的ABS系統(tǒng)的設(shè)計(jì)； 4.實(shí)現(xiàn)對ABS系統(tǒng)對汽車制動(dòng)的智能控制。 第 3 頁 參考文獻(xiàn) [01] 張?jiān)孪?趙英君編著，電控汽車ABS培訓(xùn)教程，黑龍江科學(xué)技術(shù)出版社，2007 [02] 馮淵編著，汽車電子控制技術(shù)，機(jī)械工業(yè)出版社，2007 [03] 付百學(xué) 編著，汽車電子控制技術(shù)，機(jī)械工業(yè)出版社，2000 [04] 齊曉杰 趙晨光 李延臣編著，汽車制動(dòng)系統(tǒng)，化學(xué)工業(yè)出版社，2005 [05] 齊曉杰 安永東 王祥之編著，汽車液壓、夜力與氣壓傳動(dòng)，化學(xué)工業(yè)出版社，2007 [06] 李朝青編著，單片機(jī)原理及接口技術(shù)，北京航空航天大學(xué)出版社，2005 [07] A. R. Savkoor. The Relation of the Adhesion Friction of Rubber to the Friction Between Tire and Ground. l Ith FISITA Congress, June 1996 [08] J. L. Harried et al. Measurement of Tire Brake Force Characteristics as Related to Wheel Slip (Antilock) Control. SAE paper 690214, Detroit,USA, 1969 [09] B. Yim, G. R. Olsson, P. G. Fielding. Highway Vehicle Stability in Braking Maneuvers. SAE Trans. 79, 1970, 700515 [10] James P, Cook P. Using rap id p rototyp ing tools for the integration of control system for comp lex technology concep tvehicles [M ].England: Prodrive Ltd, 2001. [11] The Mathworks. Simulink user ’s guide [M ]. Michigan: The Mathworks, 2001. [12] 馬明星,毛務(wù)本,朱錦興. 車輛防抱死制動(dòng)系統(tǒng)(ABS)控制算法的研究[ J ]. 城市車輛, 2002, (2) : 21223. [13] 劉昭度、陳思忠，汽車制動(dòng)系統(tǒng)電子控制技術(shù)的發(fā)展，汽車電子， 1996(8) [14] 司利增，汽車防滑控制系統(tǒng)--ABS與ASR，人民交通出版社，1996 [15] 孟嗣宗、崔艷萍，現(xiàn)代汽車防抱死制動(dòng)系統(tǒng)和驅(qū)動(dòng)力控制系統(tǒng)，北 京理工大學(xué)出版社，1997 [16] 李巖等，汽車ABS和安全氣囊面臨的挑戰(zhàn)和對策，世界汽車，1998 [17] 李巖，ABs信號采集與處理的試驗(yàn)研究與分析，北京理工大學(xué)學(xué)位論文，1999 [18] 余志生主編，汽車?yán)碚?，機(jī)械工業(yè)出版社，1989 [19] 潘旭峰等編著，現(xiàn)代汽車電子技術(shù)，北京理工大學(xué)出版社，1998 [20] (日)ABS株式會(huì)社，汽車制動(dòng)防抱裝置 (ABS)構(gòu)造與原理， 李朝祿、劉榮華譯，機(jī)械工業(yè)出版社，1995 [21] 程軍. 汽車防抱死制動(dòng)系統(tǒng)的理論與實(shí)踐[M ]. 北京:北京理工大學(xué)出版社, 1999. 摘 要 ABS系統(tǒng)可以顯著提高或改善汽車緊急制動(dòng)時(shí)的操控性和穩(wěn)定性，縮短了制動(dòng)距離，是一種新型的汽車電子控制產(chǎn)品，并得到了越來越廣泛的應(yīng)用。 本文以轎車為研究對象，展開對汽車ABS的研究。主要完成了以下的工作： 通過對單個(gè)車輪時(shí)的受力分析確定了影響車輪附著系數(shù)的主要因素； 通過比較電磁感應(yīng)式輪速傳感器和霍爾效應(yīng)傳感器的性能優(yōu)缺點(diǎn)，采用并設(shè)計(jì)了霍爾效應(yīng)式輪速傳感器； 通過對控制結(jié)構(gòu)的分析設(shè)計(jì)了以INTEL公司生產(chǎn)的80C196KC單片機(jī)為核心的實(shí)時(shí)控制系統(tǒng)，包括信號輸入電路、控制輸出電路、驅(qū)動(dòng)電路等硬件部分； 經(jīng)比較各種控制方案，確定了“邏輯門限制法”作為控制方案，并選用加速度和滑移率的組合作為控制參數(shù)。采用事件門限來計(jì)算車輪的轉(zhuǎn)速。 本文通過學(xué)習(xí)比較根據(jù)所學(xué)只是設(shè)計(jì)了ABS控制系統(tǒng)。從理論上實(shí)現(xiàn)了ABS的控制功能，完成了設(shè)計(jì)要求。在設(shè)計(jì)過程中對汽車制動(dòng)理論和制動(dòng)裝置有了較為深入的了解，擴(kuò)大了自己的知識(shí)面，自己解決問題的能力也得到了提高。 關(guān)鍵詞：防抱死制動(dòng)系統(tǒng) 電子控制單元 門限值滑移率 輪速傳感器  ABSTRCT Anti-lock Braking System (ABS) is an important device to improve the active safety of vehicle. ABS can greatly improve steering control ability during the brake maneuver and shorten stopping distance. Today with the improvement of the vehicle speed, ABS is applied widely. With the car as the research object, the research on ABS has been carried on. And a series of work were finished: The dynamic situation of wheel was analyzed. Then, the model of hydraulic ABS was built and assured main complication affect the wheeler appendiculate coefficient. By comparing the capability of electromagnetism rotate speed sensor with Houer rotate speed sensor, we chose the later, and have designed a sensor of this kind. Via analyse the control system structure, we have designed a real-time system with the singlechip 80c196kc produced by Intel company .It comprises with signal input, singlechip system, output, drive electro circuit and otherwise parts of hardware segment. After comparing the different projects of the controllers, the method of logic rate has been comfirmed, and the combination of acceleration and slippage rate as been chose as control parameters. The time gate method to calculate the wheel rotate speed was adopted. In this paper, based on the knowledge I have mastered, I designed a ABS system and realized the control function in theory, accomplished my assignment. I have gotten a in-depth understand of motorcar trig theory and equipment. It widen my knowledge scope, improved my ability of solving problems. Kyewords: ABS electronic control slippage gate rotate speed sensor 附 錄 附錄A. Car ABS Technology and Development Trend In the car before the emergence of abs, used car is the open loop brake system. Its characteristic is the brake torque only and drivers of the size of the manipulation of the force, braking force distribution regulation and the size of the brakes on and type. With no wheel the motion of feedback signal measurement, can't know during wheel brake speed and holding in death, car you may adjust accordingly wheel cylinder or the gas chamber of the size of the brake pressure. So in an emergency brake, inevitably appear wheel on the ground, holding in death dragged the phenomenon of sliding. When the wheel lock, the ground of the performance was poor, the lateral attached can provide the lateral adhesion is small, car by external force in any minute under the action of will appear direction, easily happened instability problems of traffic accidents. In the wet pavement or snow and ice on the road, the direction of brake the instability of the phenomenon can more serious. towing It is through the basic function of sensors' wheel each transient state of motion, and according to the motion correspondingly adjust the size of the brake torque in to avoid the wheels holding in death, it is a phenomenon of closed-loop brake system. It is the electronic control technology in cars of the most successful application project, one of auto brake antilock brake systems can make the car in the braking maintain stability and shorten the direction braking distance, effectively improve the driving safety. Car ABS can say is the most important car safety history of the three great inventions (the other two are airbag with seat belt), ABS is also other safety device (such as ESP driving dynamic stability system and EBD braking forces based distribution system) Because money spent too big, ABS the practical use of the early railway vehicle or aircraft. 70 s, digital electronic technology and large scale integrated circuit, for the rapid development of ABS system lays a foundation to practical application. Bosch company in 1978 first launched the digital electronic control unit of the brake system, and ABS2 Bosch holding device in the Mercedes Benz, which opened on the modern ABS system development sequence Although the Bosch ABS2 of electronic control device is a separation of the components, but due to the digital electronic control device and analog electronic control device, the reaction speed, compared to the control accuracy and reliability are significantly improved, therefore, Bosch ABS2 control effect already is quite good. From then on, Europe, America and Japan, many professional company and brake car companies have developed a variety of ABS system. According to statistics, the whole world has more than 60% of new cars equipped with ABS device. When the car brake wheel speed and the differences between body speed, can lead to the wheel and the road, when the wheel slippage between produce pure rolling way and the pavement at contact, the slip rate is zero, and wheel lock the slip rate is 100%. When the slip rate between 10% ~ 30%, the largest transfer of power. The basic principle of braking antilock brake system (2, 3] is based on the above research, through the control regulation system in power, braking process, to the wheel in the slip rate control, within the scope of the right to obtain the best braking effect. ABS system hardware mainly by the wheel sensor, electronic control devices, brake pressure regulator three major components, constitute a to the slip rate is the control of the target of the closed-loop control system. The wheel speed sensor and the data transfer to the electronic control device. Control device is a microprocessor, according to the wheel speed sensor signal to calculate the speed of the car. In the braking process, reducing speed and control device of programmed ideal reducing the speed of characteristic curve in comparison. If control device judge the wheel reducing speed too large and the wheel will embrace died, signal to hydraulic regulator, hydraulic regulator is according to the control device of the signal to the brake wheel cylinder of hydraulic control (the boost, the pressure or blood pressure). Brake pressure to adjust the frequency of the cycle up to 6 ~ 20 H z. ABS technology at the core of theproblem is the control algorithm of research. The control car ABS is a complex, essential nonlinear control problem. In recent years, domestic and foreign scholars in the control of ABS calculate Method on the many theoretical research, mainly in the following several control methods. Now automotive ABS system most of the products are the addition, subtraction speed control, and additional threshold some auxiliary threshold, not involve specific mathematical model. Threshold control for nonlinear systems is an effective control method. In the braking process, can be a primary angular velocity threshold, when actual angular velocity over the threshold, the controller order to release, the wheel brake pressure to rotate faster; A Angle acceleration, when the threshold of angular velocity to reach this threshold, controller and issue commands to control moment, increased, and the wheel as slow movement. Can use a wheel angular velocity sensor as a single wheel signal, and electronic controller in set reasonable add, subtract speed threshold method, can come true to the embrace of the brake cycle. Logic threshold control the fault is that control system of the various threshold and the holding time is from repeated test that experience, and no sufficient data the theoretical basis of the stability of the system and the quality is difficult to evaluation. The optimal control method is based on state space method of modern control theory method. The optimal control method and threshold control method is different, it is a kind of based on the analysis of the model control method. The idea is based on the abs all the control requirements, according to the principle of optimization for brake antilock brake system optimal control goals. This control method is considered the control process of state changes course and make the control process smoothly; Defect is the control effect of quality mainly depends on the mathematical model of the system, quality control is difficult to accurately. The classic of PID control parameters setting is set up on the basis of gather together in try, as long as the scene setting PID parameters, you can get right better control effect. In the ABS in a definition of the expected sliding rate S and actual sliding rate for the input of the difference of the PID, the PID control algorithm is calculate control air pressure value feedback to brake system, a typical feedback control. Its defect is control effect quality depends on the accuracy of the parameter setting. Fuzzy control is based on experience of the rules of the control, and have not rely on the mathematical model of the object, easy to use the experience, knowledge is robust and simple practical. Control rules to the law of thinking. Defect is no effective general calculation method, can only rely on industrial automation instrument and a plan of the device experience and repeated test. By automobile braking antilock brake the basic principle of the braking process, it is known that the nature of the problem is to the wheel the slip rate control adhesion coefficient in the peaks of the Sk, the sliding mode variable structure according to the system of the state, and deviation and at that time, in different derivative value area, in order to control the ideal switch mode switch control the amount of and symbols, in order to ensure that the system in sliding area is small, within the scope of the state trajectory S sliding in the pitch curve sliding into a control target tsinghua university song jian and other car braking process according to the physical nature of international proposed first to brake dissipation power as the target of the control method. Considering the car of the deceleration process, in fact, is the average kinetic energy of the car into other forms of energy dissipation process. Accordingly, if you take the reasoning brake friction power (or says dissipation power) maximum control targets of ABS, have the potential to give consideration to the braking stability and brake performance. This method than the threshold method has good stability, high efficiency of braking, strong adaptability and control of road surface features obvious etc. Characteristics. Research shows that the control method can have a good application prospect. Drive torque system (hereinafter referred to the ASR) is perfect and added. ABS ASR system can improve the car is in the most slippery road stability and acceleration of the electronic device. Its role is mainly through the control engine torque and a car braking system means to control the driving force, to prevent the wheels idling sliding, maintain the best driving force. ABS guarantee The car braking process, the stability of the direction is guaranteed the car ASR process (beginning, the direction of the acceleration) stability and handling. Many of the cars, the modern electronic control device equipped with ABS ASR electronic control signal devices to exchange interface. And ASR and a major part of the ABS (such as electronic controller, wheel sensor, brake pressure regulators) can be used with or Shared with the car with the ABS ASR system, just the premise, differential control valves and engine control cylinder engine can. This shows, ABS and ASR combination, can make full use of the relevant parts of the car, and active safety will be more assured. Vehicle stability control device (hereinafter referred to as VSC) use two sensors were sensor car yaw-rate and lateral acceleration, and car will shift to Angle and the actual direction are compared. When it found the car is not according to the intention of motorists road, immediately sent to the ASR and ABS correction signal, indicating they take measures to make the car to the correct direction. These system although functions and the structure is different, but the work is similar to the process is sensor signal, she is calculated, the execution processing ECU institutions take corresponding actions. In the system composition, pick the accuracy of the sensor signal directly influence the results of ECU, additional, wheel sensor most is installed in the bad environment, especially near to heat resistant, vibrationresistant sex, the magnetic, corrosion resistance has high request, to the improvement of the performance of the sensor is very important. ABS and electronic throttle control system, electronic all control type (or half controlled) suspension, electronic control four-wheel steering, electronic control hydraulic turn To the electronic control, automatic transmission, cruise control system, global positioning system, etc. Various kinds of electronic control system, can make the combined use of car movement remains in the best state. Along with the electronic control units in car has more and more application, vehicle electronic equipment of the data communication between becomes more and more important, the distributed control system for infrastructure automobile vehicle electronic network system is very necessary. Large amounts of data exchange, high reliability and rapid sex is cheap to automobile electronic network system requirements. The network system, the processor independent operation, the control to improve the performance of the car on something, and in the other processors need to provide according to service. When The structure of the network inside the car relies mainly on the bus transmission technology. Car through a kind of communication is bus transfers of agreement will car electronic control units (engine, ABS, automatic transmission, etc.), intelligent sensor, intelligent instrument, and link up a car interior network. Its advantages are: reduced the number of cable and wire harness in volume, improve the electronic system reliability and maintainability; The general sensors, achieve the purpose of sharing data; Improve the flexibility of the system, that is, through the system software can realize the change of system function. Car ABS technology has been acknowledged as the world, ABS change Good the car brake performance, and the shorter the braking distance. Avoid the wheel lock so as to avoid the loss of car to ability, lose the direction stability of the phenomenon. It would be expected that the recent all kinds of vehicles will be equipped with the technology. Of course, ABS technology is still have defects, such as the stability of system still need to improve, control algorithm of further research and improvement. Through the simulation shows, in the design of fuzzy controller, through the adjustment of the fuzzy controller membership functions, the error in the basic fuzzy subsets of domain non-uniform distribution and ZO interval of the retreat to small enough, without any increase in the control strategy of the case, make the steady-state error of the fuzzy controller is greatly reduced, has the good control effect, short setting time, no overshoot, the improved fuzzy controller in steady precision at the same time, continued to parameter time-variance and fuzzy controller of interference has strong adaptability. All in all, this method improves the fuzzy control the system steady control precision, to improve the system dynamic and static quality. Due to the adjustment of the fuzzy controller membership function is very convenient, and therefore, this method is simple and useful for the fuzzy controller is widely used, provide an easy method. 附錄B. 汽車ABS技術(shù)及其發(fā)展趨勢 在汽車防抱死制動(dòng)系統(tǒng)出現(xiàn)之前, 汽車所用的都是開環(huán)制動(dòng)系統(tǒng)。其特點(diǎn)[ 1, 2] 是制動(dòng)器制動(dòng)力矩的大小僅與駕駛員的操縱力、制動(dòng)力的分配調(diào)節(jié)以及制動(dòng)器的尺寸和型式有關(guān)。由于沒有車輪運(yùn)動(dòng)狀態(tài)的反饋信號, 無法測知制動(dòng)過程中車輪的速度和抱死情況, 汽車就不可能據(jù)此調(diào)節(jié)輪缸或氣室制動(dòng)壓力的大小。因此在緊急制動(dòng)時(shí), 不可避免地出現(xiàn)車輪在地面上抱死拖滑的現(xiàn)象。當(dāng)車輪抱死時(shí), 地面的側(cè)向附著性能很差, 所能提供的側(cè)向附著力很小, 汽車在受到任何微小外力的作用下就會(huì)出現(xiàn)方向失穩(wěn)問題, 極易發(fā)生交通事故。在潮濕路面或冰雪路面上制動(dòng)時(shí), 這種方向失穩(wěn)的現(xiàn)象會(huì)更加嚴(yán)重。汽車防抱死制動(dòng)系統(tǒng)( Anti􀀁lock Braking System簡稱ABS)的出現(xiàn)從根本上解決了汽車在制動(dòng)過程中的車輪抱死問題。它基本功能就是通過傳感器感知車輪每一瞬時(shí)的運(yùn)動(dòng)狀態(tài), 并根據(jù)其運(yùn)動(dòng)狀態(tài)相應(yīng)地調(diào)節(jié)制動(dòng)器制動(dòng)力矩的大小以避免出現(xiàn)車輪的抱死現(xiàn)象, 因而是一個(gè)閉環(huán)制動(dòng)系統(tǒng)。它是電子控制技術(shù)在汽車上最有成就的應(yīng)用項(xiàng)目之一, 汽車制動(dòng)防抱死系統(tǒng)可使汽車在制動(dòng)時(shí)維持方向穩(wěn)定性和縮短制動(dòng)距離, 有效提高行車的安全性。 汽車ABS可以說是汽車安全歷史上最重要的三大發(fā)明之一(另外兩個(gè)是安全氣囊與安全帶),ABS也是其他安全裝置(如ESP行車動(dòng)態(tài)穩(wěn)定系統(tǒng)與EBD剎車力分配系統(tǒng))的基礎(chǔ)。精于汽車電子技術(shù)的德國博世( Bosch)公司研發(fā)ABS系統(tǒng)的起源要追溯到1936年, 當(dāng)年博世申請了機(jī)動(dòng)車輛防止剎車抱死裝置􀀁的專利。1964年(集成電路誕生)博世公司再度開始ABS的研發(fā), 最后有了􀀁 通過電子裝工業(yè)儀表與自動(dòng)化裝置置控制來防止車輪抱死是可行的􀀁結(jié)論, 這是ABS名詞在歷史上第一次出現(xiàn)。世界上第一具ABS原型機(jī)于1966年出現(xiàn), 向世人證明􀀁縮短剎車距離􀀁并非不可能。因?yàn)橥度氲馁Y金過于龐大, ABS 初期的應(yīng)用僅限于鐵路車輛或航空器。70年代后期, 數(shù)字式電子技術(shù)和大規(guī)模集成電路的迅速發(fā)展, 為ABS系統(tǒng)向?qū)嵱没l(fā)展奠定了基礎(chǔ)。博世公司在1978年首先推出了采用數(shù)字式電子控制裝置的制動(dòng)防抱系統(tǒng)博世ABS2, 并且裝置在奔馳轎車上, 由此揭開了現(xiàn)代ABS 系統(tǒng)發(fā)展的序 幕。盡管博世ABS2的電子控制裝置是由分離元件組成的, 但由于數(shù)字式電子控制裝置與模擬式電子控制裝置相比, 其反應(yīng)速度、控制精度和可靠性都顯著提高, 因此, 博世ABS2的控制效果已相當(dāng)理想。從此以后, 歐、美、日的許多制動(dòng)器專業(yè)公司和汽車公司相繼研制了形式多樣的ABS系統(tǒng)。據(jù)統(tǒng)計(jì), 目前全世界已有超過60%的新車裝有ABS裝置。 汽車制動(dòng)時(shí)由于車輪速度與車身速度之間存在著差異, 會(huì)導(dǎo)致車輪與路面之間產(chǎn)生滑移, 當(dāng)車輪以純滾動(dòng)方式與路面接觸時(shí), 滑移率為零, 而車輪抱死時(shí)其滑移率為100% 。當(dāng)滑移率在10% ~ 30% 之間時(shí), 傳遞最大的制動(dòng)力。制動(dòng)防抱死系統(tǒng)的基本原理[ 2, 3] 就是依據(jù)上述研究成果, 通過控制調(diào)節(jié)制動(dòng)力, 在制動(dòng)過程中, 把車輪滑移率控制在合適的范圍內(nèi), 取得最佳的制動(dòng)效果。ABS系統(tǒng)硬件構(gòu)成主要由輪速傳感器、電子控制裝置、制動(dòng)壓力調(diào)節(jié)器3大部分組成, 構(gòu)成一個(gè)以滑移率為控制目標(biāo)的閉環(huán)控制系統(tǒng)。傳感器測量車輪轉(zhuǎn)速并這一數(shù)據(jù)傳送至電子控制裝置上?？刂蒲b置是一個(gè)微處理器, 根據(jù)車輪轉(zhuǎn)速傳感器信號來計(jì)算車速。在制動(dòng)過程中,減速度與控制裝置中預(yù)先編制的理想減速度的特性曲線相比較。如果控制裝置判斷出車輪減速度太大和車輪即將抱死時(shí), 就發(fā)出信號給液壓調(diào)節(jié)器, 液壓調(diào)節(jié)器就根據(jù)控制裝置的信號對制動(dòng)輪缸的油壓進(jìn)行控制(升壓、保壓或降壓)。制動(dòng)壓力調(diào)節(jié)循環(huán)的頻率可達(dá)6~ 20H z。ABS技術(shù)的一個(gè)核心問題就是控制算法的研究。汽車ABS的控制是一個(gè)復(fù)雜的、本質(zhì)非線性的控制問題。近年來, 國內(nèi)外學(xué)者對ABS 的控制算 法進(jìn)行了很多理論研究, 主要有以下幾種控制方法。目前汽車ABS系統(tǒng)絕大多數(shù)產(chǎn)品都是采用加、減速度門限值控制, 并附加一些輔助的門限值, 并不涉及具體的數(shù)學(xué)模型。門限控制是對非線性系統(tǒng)的一種有效控制方法。在制動(dòng)過程中, 可以預(yù)選一個(gè)角速度門限值, 當(dāng)實(shí)際的角速度超過此門限值時(shí), 控制器發(fā)出指令, 開始釋放制動(dòng)壓力使車輪得以加速旋轉(zhuǎn); 一個(gè)角加速度門限值, 當(dāng)車輪的角速度達(dá)到此門限值時(shí), 控制器又發(fā)出指令, 使控制力矩增大, 車輪作減速運(yùn)動(dòng)?？梢圆捎靡粋€(gè)車輪角速度傳感器作為單輪信號, 同時(shí)在電子控制器中設(shè)置合理的加、減速度門限值, 就可以實(shí)現(xiàn)防抱制動(dòng)的循環(huán)。邏輯門限控制的缺點(diǎn)在于控制系統(tǒng)中的各種門限及保壓時(shí)間都是從反復(fù)試驗(yàn)中得出的經(jīng)驗(yàn)數(shù)據(jù), 而無充分的理論依據(jù), 系統(tǒng)的穩(wěn)定性等品質(zhì)難以評價(jià)。最優(yōu)控制方法是基于狀態(tài)空間法的現(xiàn)代控制理論方法。它可以根據(jù)車輛􀀁 地面系統(tǒng)的數(shù)學(xué)模型,采用狀態(tài)空間的概念, 在時(shí)間域內(nèi)研究汽車防抱死制動(dòng)系統(tǒng)。最優(yōu)控制方法和門限值控制方法不同,它是一種基于模型分析的控制方法。其思路是根據(jù)防抱死制動(dòng)系統(tǒng)的各項(xiàng)控制要求, 按照最優(yōu)化的原理來求得制動(dòng)防抱死系統(tǒng)的最優(yōu)控制目標(biāo)。這種控制方法的優(yōu)點(diǎn)是考慮了控制過程中狀態(tài)變化的歷程而使控制過程平穩(wěn); 缺點(diǎn)是控制效果的優(yōu)劣主要依賴于系統(tǒng)的數(shù)學(xué)模型, 控制質(zhì)量難以準(zhǔn)確把握。經(jīng)典PID 控制的參數(shù)整定是建立在試湊基礎(chǔ)上的, 只要現(xiàn)場整定PID參數(shù)合適, 就會(huì)得到較好的控制效果。 在ABS中定義期望的滑移率S 與實(shí)際滑移率之差為PID 的輸入, 由PID 控制算法算出控制氣壓值反饋給制動(dòng)系統(tǒng), 構(gòu)成典型的反饋控制。其缺點(diǎn)是控制效果的好壞依賴于參數(shù)整定的準(zhǔn)確度。模糊控制是基于經(jīng)驗(yàn)規(guī)則的控制, 具有不依賴對象的數(shù)學(xué)模型, 便于利用人的經(jīng)驗(yàn)知識(shí), 具有魯棒性強(qiáng)和簡單實(shí)用等優(yōu)點(diǎn)?？刂埔?guī)則符合人的思維規(guī)律。缺點(diǎn)是沒有有效通用的計(jì)算方法, 只能依靠設(shè)工業(yè)儀表與自動(dòng)化裝置計(jì)者的經(jīng)驗(yàn)和反復(fù)調(diào)試。由汽車防抱死制動(dòng)的基本原理可知, 其制動(dòng)過程的本質(zhì)問題是把車輪的滑移率控制在附著系數(shù)的峰值點(diǎn)Sk, 則滑動(dòng)模態(tài)變結(jié)構(gòu)根據(jù)系統(tǒng)當(dāng)時(shí)的狀態(tài)、偏差及其導(dǎo)數(shù)值, 在不同的控制區(qū)域, 以理想開關(guān)的方式切換控制量的大小和符號, 以保證系統(tǒng)在滑動(dòng)區(qū)域很小的范圍內(nèi), 狀態(tài)軌跡S 沿滑動(dòng)換節(jié)曲線滑向控制目標(biāo)清華大學(xué)宋健等根據(jù)汽車制動(dòng)過程的物理本質(zhì)在國際上首次提出了一種以制動(dòng)器耗散功率最大為目標(biāo)的控制方法?？紤]到汽車減速制動(dòng)的過程, 實(shí)際上是將汽車的平均動(dòng)能轉(zhuǎn)化為其他形式能量的耗散過程。據(jù)此推理, 如果取制動(dòng)器的摩擦功率(或稱耗散功率)最大為ABS的控制目標(biāo), 則有可能兼顧制動(dòng)穩(wěn)定性和制動(dòng)效能。該方法較之門限值方法具有制動(dòng)穩(wěn)定性好、效能高、對路面適應(yīng)性強(qiáng)和控制特征明顯等特點(diǎn)。研究表明, 這種控制方法會(huì)有良好的應(yīng)用前景。驅(qū)動(dòng)防滑系統(tǒng)(簡稱ASR)是對ABS的完善和補(bǔ)充。ASR系統(tǒng)是能提高汽車在易滑路面上的穩(wěn)定性和加速性的電子裝置。其作用主要是通過控制發(fā)動(dòng)機(jī)扭矩和汽車的制動(dòng)系統(tǒng)等手段來控制驅(qū)動(dòng)力, 防止車輪空轉(zhuǎn)打滑, 保持最佳驅(qū)動(dòng)力。ABS保證 了汽車制動(dòng)過程中方向的穩(wěn)定性, ASR 則保證了汽車行駛過程中(起步、加速時(shí))的方向穩(wěn)定性和操縱性?，F(xiàn)代的很多轎車中, ABS電子控制裝置設(shè)有與ASR 電子控制裝置交換信號的接口。并且ASR 和ABS的主要部件(如電子控制器、輪速傳感器、制動(dòng)壓力調(diào)節(jié)器)可以通用或共用, 裝有ABS的汽車在裝用ASR 系統(tǒng)時(shí), 只需加裝差速制動(dòng)閥、發(fā)動(dòng)機(jī)控制閥和發(fā)動(dòng)機(jī)控制缸即可。由此可見, ABS與ASR結(jié)合使用, 可以充分利用有關(guān)部件, 并且汽車的主動(dòng)安全性將更有保證。車輛穩(wěn)定性控制裝置(簡稱VSC ) 利用兩個(gè)傳感器分別感測汽車橫擺角速度和汽車側(cè)向加速度,并將轉(zhuǎn)向角與實(shí)際方向進(jìn)行比較。當(dāng)它發(fā)現(xiàn)汽車并不按駕車人的意圖行駛時(shí), 就立即向ASR和ABS發(fā)出修正信號, 指示它們采取措施使汽車駛向正確的方向。這些系統(tǒng)盡管功能和結(jié)構(gòu)各異, 但工作過程很相似, 都是傳感器拾取信號, ECU 進(jìn)行計(jì)算處理,執(zhí)行機(jī)構(gòu)采取相應(yīng)動(dòng)作。在這些系統(tǒng)組成中, 傳感器拾取信號的準(zhǔn)確程度直接影響ECU 的計(jì)算結(jié)果,另外, 輪速傳感器大多數(shù)是安裝在車輪附近, 環(huán)境惡劣, 特別是對耐熱性、耐振性、防磁性、耐腐蝕性有很高的要求, 對傳感器這些方面性能的改進(jìn)十分重要。ABS與電子油門控制系統(tǒng)、電子全控式(或半控式) 懸掛、電子控制四輪轉(zhuǎn)向、電子控制液壓轉(zhuǎn) 向、電子控制自動(dòng)變速器、巡航控制系統(tǒng)、全球定位系統(tǒng)等各種電子控制系統(tǒng)的組合使用, 可以使汽車的運(yùn)動(dòng)始終保持在最佳狀態(tài)。隨著電控單元在汽車中的應(yīng)用越來越多, 車載電子設(shè)備間的數(shù)據(jù)通信變得越來越重要, 以分布式控制系統(tǒng)為基礎(chǔ)構(gòu)造汽車車載電子網(wǎng)絡(luò)系統(tǒng)是很有必要的。大量數(shù)據(jù)的快速交換、高可靠性及廉價(jià)性是對汽車電子網(wǎng)絡(luò)系統(tǒng)的要求。網(wǎng)絡(luò)系統(tǒng)中,各處理機(jī)獨(dú)立運(yùn)行, 控制改善汽車某一方面的性能,同時(shí)在其他處理機(jī)需要時(shí)提供據(jù)服務(wù)。汽車內(nèi)部網(wǎng)絡(luò)的構(gòu)成主要依靠總線傳輸技術(shù)。汽車總線傳輸是通過某種通訊協(xié)議將汽車中各種電控單元(發(fā)動(dòng)機(jī)、ABS、自動(dòng)變速器等)、智能傳感器、智能儀表等聯(lián)接起來, 而構(gòu)成的汽車內(nèi)部網(wǎng)絡(luò)。其優(yōu)點(diǎn)有: 減少了線束的數(shù)量和線束的容積, 提高了電子系統(tǒng)的可靠性和可維護(hù)性; 采用通用傳感器, 達(dá)到數(shù)據(jù)共享的目的; 改善了系統(tǒng)的靈活性, 即通過系統(tǒng)的軟件可以實(shí)現(xiàn)系統(tǒng)功能的變化。 汽車ABS技術(shù)已經(jīng)得到了全球的公認(rèn), ABS改善了汽車的制動(dòng)效能, 縮短了制動(dòng)距離。避免了車輪抱死, 從而避免了汽車喪失轉(zhuǎn)向能力、失去方向穩(wěn)定性的現(xiàn)象發(fā)生。可以預(yù)計(jì), 近期各種車輛都必將裝備這種技術(shù)。當(dāng)然, ABS技術(shù)仍有缺陷, 比如系統(tǒng)的穩(wěn)定性還需提高, 控制算法還需進(jìn)一步的研究和改善。通過仿真可見, 在設(shè)計(jì)模糊控制器時(shí), 通過調(diào)整模糊控制器的隸屬度函數(shù), 使誤差的基本模糊子集在論域上不均勻分布且ZO 的區(qū)間縮到足夠小, 在不增加控制策略的情況下, 使得模糊控制器的穩(wěn)態(tài)誤差大大減小, 具有良好的控制效果, 調(diào)節(jié)時(shí)間短、無超調(diào), 在提高模糊控制器的穩(wěn)態(tài)精度的同時(shí), 仍保持著模糊控制器對參數(shù)時(shí)變和對干擾具有較強(qiáng)的適應(yīng)能力?？傊? 該方法提高了模糊控制系統(tǒng)的穩(wěn)態(tài)控制精度, 改善了系統(tǒng)的動(dòng)、靜態(tài)品質(zhì)。由于調(diào)整模糊控制器的隸屬度函數(shù)非常方便, 因此, 該方法簡便實(shí)用, 為模糊控制器廣泛應(yīng)用, 提供了一種簡便方法。