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1、附录附录1Automobile anti-lock braking system (ABS)Abstract: This article introduced briefly the automobile anti-lock braking system (Anti-lock Braking System, is called ABS) the control principle, the control technology which used in the present automobile anti-lock braking system has carried on the sum
2、mary, and has carried on the forecast to its trend of development.Key word: Automobile anti-lock braking system control technology1. outlineAlong with automobile industrys rapid development and highways unceasing construction, automobiles travel security more and more takes seriously for the people.
3、 To satisfy in comprehensively the brake process the automobile to the brake request, causes the brake braking force assignment to hasten reasonably. The automobile anti-lock braking system (i.e. ABS) more and more has applied on the automobile.“ABS” Chinese translates is “against deadlocks the brak
4、e system”. It is one kind has the skid prevention, against to deadlock and so on merit auto safety control systems. ABS is in the convention brake system foundation advanced version technology, separable mechanical and electronic formula two kinds.On the modern automobile installs the anti-lock brak
5、ing system massively, ABS both has the ordinary braking systems brake function, and could prevent the wheel to deadlock, enables the automobile still to change under the stopping, guaranteed that automobiles brake yawing stability, prevented to have the side-slipping and to run, was on the present a
6、utomobile is most advanced, the brake effect best arresting gear.The ordinary braking system applies the brake in the slippery road surface, or in emergency brake, because the wheel is easy the braking force to surpass the tire and the ground friction force hugs safely dies.The automobile anti-lock
7、braking system is refers to the automobile in the brake process to be able the real-time determination wheels glide rate, the automatic control function on wheels braking moment, prevents the wheel to hug dies. Thus obtains the best brake potency the electronic installation. It can wheels glide rate
8、 control in certain scope, use fully between the tire and the road surface adhesion, reduces the stopping distance effectively, obviously enhances when the car braking controllability and stability, when each kind of traffic accident which has avoided the wheel hugs dies easy to appear. along with b
9、rake intensitys increase, the wheel rolling ingredient are getting fewer and fewer, but skids the ingredient to be getting more and more, generally explains in the brake process with glide rate S to skid ingredient how many. The glide rate is bigger, the glide ingredient are less.And: u- wheel cente
10、r speed; r- does not have time the ground braking force wheel rolling radius; w- wheels angular speed.Longitudinal and the lateral adhesion coefficient may express for the wheel slip rate function (e.g. Figure 1). The most greatly longitudinal coefficient of adhesion corresponds the glide rate is ca
11、lled critical point of fixity SK. Grips fast the pace according to the control theory is smaller than the SK region is called the stable brake area, what SK later has custom-made unstable moves the area. ABS is precisely uses between the path and tires relations, compulsory wheel slip rate control n
12、earby critical point of fixity SK, enables the road surface adhesion property to obtain the fullest display, thus achieves the best brake effect.Figure 1 coefficient of adhesion - glide rate curveAt present uses ABS mainly by a round fast sensor, the electronic control unit, appendices and so on pre
13、ssure control valve and group of lines, pipeline is composed. The ABS development is mainly studies the design optimization operation and the control procedure software, realizes the real-time precise brake adjustment technology, simultaneously raises hardwares level.2. Control technology used by AB
14、S nowThe ABS control effect is decided control technology 4 which to a great extent uses in the system. At present uses is mainly the logical threshold value control technology. To further enhance ABS the performance, but also proposed some based on the glide rate control technology, like the PID co
15、ntrol, the glide modality change the structure controls, fuzzy control and so on. Each kind of control approaches the expectation by the different control rule the spot. 2.1 PID controlsThe definition expects glide rate S0 and difference of the actual glide rate S for ning error e=S-S0, then the PID
16、 control rule may be represented as:Therefore, the ABS controllers design sums up finally as, according to the ABS dynamic system, determined group of best parameter Kp, Ki and Kd, enable wheels glide rate to approach hypothesis goal S0 by the quickest way.2.2 The glide modality changes the structur
17、e controlAgainst holds the dead brake by the automobile the basic principle to be possible to know, its brake processs essential question is wheels glide rate control in coefficient of adhesion peak point Sk, then the glide modality changed structure basis system condition, the deviation and the der
18、ivative value then, in the different controlled area, by perfect switchs way hand-off control quantitys size and the mark, the guarantee system in the glide region very small scope, the state point locus (S,S) along moved the festival curve to slide slippery to the control objective (Sk,0). usually
19、takes the braking moment for controlled variable U, the cut condition is:And Mb-, Mb+ represent the braking moment which decided by the governing system to reduce, to increase two different conditions separately.For the cut function, e=S-Sk is the actual glide rate relative target point deviation.2.
20、3 Fuzzy controlRegarding take the glide rate as controlled members anti-lock braking system, its input value takes the expectation glide rate and wheel actual glide rate deviation E as well as deviations rate of change EC, the output for the brake line flowing tubing head pressure. Uses the belt mod
21、ification factor the fuzzy controller, uses the control list summary which the fuzzy reasoning algorithm forms is an analysis formula:U = E + (1-)ECAnd Alpha is the modification factor, Alpha the value size has reflected directly to the deviation and the deviation rate of change weighting degree. Th
22、rough the adjustment modification factor Alpha, may change the control rule. When Alpha is big, indicated that is big to deviations weighting, the step response is quick, the control energy mainly uses in reducing the deviation, but easy to present the over modulation; When Alpha is small, the contr
23、ol goal reduces the over modulation, but the response process is slow. Usually uses the belt two Alpha values the modification factor expressions to be able to request on the satisfiability, namely:And, modification factor 1, 2 (0,1), and 12.4 Logical threshold value controlThis method establishes s
24、ome control limit in advance to certain controlled variable (threshold) the value, when applies the brake, according to the computation real-time parameter value and the corresponding threshold values size relations, determines wheels state of motion, thus the control adjustment brake pressure, gain
25、s enough big brake intensity and the good yawing stability. Often includes as the ABS controlled variable: Wheel skidding rate S, the wheel rotates the angle adds (reduces) the speed Omega and the rate of change . and so on three kind of description wheel movement situation or dynamics condition par
26、ameter. Because only uses a controlled variable difficulty with to guarantee that ABS has the good performance under each kind of travel condition, therefore, the logical threshold value control method usually rotates at present the wheel the angle adds (reduces) the speed to take the primary contro
27、l parameter, but takes wheels glide rate S the secondary control parameter. And the glide rate is from each wheel fast signal after certain logic determined automobiles reference velocity, calculates the reference glide rate, has the difference with the actual glide rate.2.5 Double parameter control
28、Double parameter controls ABS, by the vehicle speed sensor (velocity radar), a round fast sensor, the control device (computer) and the implementing agency is composed.Its principle of work is the vehicle speed sensor and a round fast sensor, separately signal input the vehicle speed and round fast
29、the computer, calculates the actual slipping rate based on the computer, and 15% one 20% does with the ideal slipping rate compares, fluctuates brakes braking force again through the solenoid valve. this kind tows the fast sensor commonly used Doppler velocity radar. When the automobile goes, the Do
30、ppler radar antenna by certain frequency to the earth launching electromagnetic wave, simultaneously receives the electromagnetic wave which unceasingly reflects, surveys the automobile radar launch and the receive differential value, then may calculate the automobile vehicle speed accurately. But t
31、urns the fast sensor to install in the transmission gearbox outer covering, actuates by the transmission gearbox output shaft, it is a pulse electrical machinery, produces frequency and round intensive direct proportion. The implementing agency and so on is composed of the solenoid valve and the rel
32、ay. Solenoid valve adjustment braking force, with the aim of maintaining the ideal slipping rate. This kind of ABS may guarantee that the slipping rate ideal control, against holds the braking quality to be good, but because increased a velocity radar, therefore the structure is complex, the cost is
33、 also high.2.6 Single parameter controlIt take controls wheels angle retarded velocity as the object, controls wheels braking force, realizes against holds the dead brake, its structure mainly by a round fast sensor, the controller (computer) and the solenoid valve is composed. For accurate meter wh
34、eel fast, the sensing and between the wheel tooth ring should leave leeway the 1mm gap. In order to avoid the water, the putty, the dust to the sensor the influence, before the installment, should the sensor replenishment butter. The solenoid valve uses in wheel brakes pressure control. Regarding fo
35、ur channel braking system, a vehicle rim has a solenoid valve; Three channel braking system, each front wheel has one, two trailing wheels use in common one. The solenoid valve has three hydraulic pressure holes, separately applies the brake with the brake master cylinder and the wheel to divide the
36、 cylinder to be connected, and can realize pressure lifting, pressure maintenance, the pressure drop accent to press the function. The principle of work is as follows:1) Pressure-rise when the solenoid valve does not work, the brake master cylinder connection and applies the brake to divide the cyli
37、nder connection respectively to go nonstop. Because the main spring intensity is big, makes charging valve opening, the brake pressure to increase. 2) pressure maintenance, when wheels brake divides in cylinders pressure grows to certain value, charging valve cut-off closure. The support maintains a
38、t the compound state, three panels seal, maintain the brake pressures mutually. 3) voltage dropping, when the solenoid valve works, the support overcomes two springs tension, opens the discharge meat to cause to apply the brake to divide cylinder pressure drop. Once the pressure reduces, the solenoi
39、d valve transforms to the pressure maintenance condition, or pressure-rise ready condition.The control device ECU primary mission is the signal which passes on various wheels sensor carries on the computation, the analysis, the enlargement and the distinction, outputs again from the output stage the
40、 command signal the solenoid valve, carries out the brake pressure adjustment task. The electronic control, by four major part is composed, input level A, controller B, output stage C, constant voltage and protective device D. Electronic controller by 4 101tz frequency actuation solenoid valves, thi
41、s is the pilot is unable to achieve. This kind of single parameter control mode ABS, because the structure is simple, the cost is low, therefore the present use is broad.Mostly has provided this kind of single parameter control mode ABS in the American Chrysler custom car. It is loaded with a round
42、fast sensor on passenger vehicles four wheels. The installment has 45 teeth or 100 tooths tooth rings on the axle tree, turns a fast sensors sensing attire to go against in the tooth ring. When the wheel rotates, causes the sensor to produce the voltage signal unceasingly, and inputs the computer, t
43、he ideal speed compares with RoM, figures out wheels speed-up or the deceleration, issues pressure-rise or the release of pressure instruction to the solenoid valve, controls applies the brake to divide the cylinder braking force.3. The problems by used the ABS system(1) replaces the brake or the re
44、placement hydraulic pressure braking system part, should arrange only in brake lines air, in order to avoid influence braking systems normal work. (2) is loaded with the ABS automobile, every year should replace a brake fluid. Otherwise, the brake fluid water absorbability is very strong, after the
45、watery, not only will reduce the boiling point, will have the corrosion, will also create the brake potency decline. (3) inspects the ABS anti-lock braking system, to cramp out the power source first. 4. Trend of developmentUses the logical threshold value control algorithm, may avoid a series of nu
46、merous and diverse theoretical analysis and to some element of certainty quota measurement. Simplified controllers design, because moreover only need determine wheels angular speed, is advantageous realizes, therefore the load cost is low. This algorithm already drew close maturely, for current auto
47、mobile ABS system universal use, but it by no means best control algorithm. Because under the different state of roads each kind of threshold value and guarantees presses the time is the empirical value which obtains after the repeated test, does not have the very explicit theory basis, therefore th
48、e ABS developments cycle is long, and the control quality guaranteed with difficulty.Easy to realize the stepless control based on the glide rate control algorithm, and has the very explicit theory to instruct, but present restricts the cost question which its development the bottleneck is mainly re
49、alizes, believed according to ours research, from now on ABS control algorithm development direction in the following several aspects.(1) aims at current widely uses the logical threshold value control algorithm which exists, the research can track the road surface characteristic change, causes the ABS each performance index to be at the optimum condition throughout the control algorithm. And the predictive control technolo
