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编号无锡太湖学院毕业设计（论文）相关资料题目： 汽车防抱死制动系统的控制方法 仿真研究 信机 系 机械工程及自动化专业学 号： 0923084学生姓名： 蒋 耀 指导教师： 陈炎冬（职称：讲师 ） （职称： ）2013年5月25日目 录一、毕业设计（论文）开题报告二、毕业设计（论文）外文资料翻译及原文三、学生“毕业论文（论文）计划、进度、检查及落实表”四、实习鉴定表无锡太湖学院毕业设计（论文）开题报告题目： 汽车防抱死制动系统的控制方法 仿真研究 信机 系 机械工程及自动化 专业学 号： 0923084 学生姓名： 蒋 耀 指导教师： 陈炎冬 （职称：讲师 ） （职称： ）2012年11月28日 课题来源生活实践科学依据（包括课题的科学意义；国内外研究概况、水平和发展趋势；应用前景等）（1）课题科学意义通过对本专业相关知识的学习以及通过对课内外科技学术的了解，我们知道，随着科学技术的飞速发展，汽车制造和设计者将智能化与信息化技术融入汽车安全控制系统中，人们对汽车的安全操控性能要求也越来越高，都在运用现代科技及大量的人力物力为汽车安全驾驶开发先进装置，使得汽车制造向更加安全、舒适，更加人性化方向发展而作为汽车安全驾驶的重要装置 ABS（制动防抱死装置） ，极大地提高了汽车在各种路面紧急制动的安全性，并且在此基础上又开发出了ASR（驱动防滑转控制系统） 、EBS（电子控制制动系统）等技术这些新技术、新装置的运用，对于改善车辆的操纵性、稳定性、安全性和舒适性等都有重大意义。（2）ABS的研究状况及其发展前景目前，车辆防抱制动控制系统(ABS)已发展成为成熟的产品，并在各种车辆上得到了广泛的应用，但是这些产品基本都是基于车轮加、减速门限及参考滑移率方法设计的。方法虽然简单实用，但是其调试比较困难，不同的车辆需要不同的匹配技术，在许多不同的道路上加以验证；从理论上来说，整个控制过程车轮滑移率不是保持在最佳滑移率上，并未达到最佳的制动效果。随着现代电子技术的飞速发展，ABS 的核心部件ECU也在不断地成熟，把多种功能电路集成于一块芯片，越来越多的ABS 系统已经选用功能强、速度快、集成度高的16 位微处理器，提高了ECU 的处理速度、控制精度和可靠性，扩大了ABS 的控制范围但是ABSASR并不能解决汽车制动中的所有问题因此由ABSASR 进一步发展演变成电子控制制动系统（EBS） ，它将是控制系统发展的一个重要的方向。EBS 系统比ABS 系统增加了各种传感器，包括三维力传感器、制动器摩擦片磨损传感器等该系统用电子控制取代机械传动，减少制动系统机械传动的滞后时，缩短制动距离。在低强度时，使摩擦片磨损最小；中等强度时，利用ABS 达到最佳的道路附着系数利用率；高强度时，施加最大的制动压力，从而获得最佳的控制制动力。研究内容 熟悉ABS在制动过程中的工作原理； 对单轮模型进行分析并建立动力学模型； 对轮胎进行分型并建立轮胎模型； 对ABS的控制系统进行分析，确定控制方法； 能够熟练使用MATLAB/Simulink，搭建框图并进行仿真。通过调整参数，对系统进行分析； 比较不同控制系统方法下的ABS工作的稳定性与准确性。拟采取的研究方法、技术路线、实验方案及可行性分析（1）实验方案 对汽车制动系统进行动力学分析，建立动力学模型，列出相应的动力学方程。根据动力学方程，用MATLAB/Simulink，搭建框图并进行仿真。通过调整参数，对系统进行分析，着重研究基于PID控制，开关控制。最后比较两种控制系统下的稳定性、快速性和准确性。（2）研究方法 分析有ABS和无ABS的情况下对系统的影响。 在不同的控制系统下，对同一个参数，分析对不同系统的影响，改变同一个参数，分析对ABS系统的影响。研究计划及预期成果研究计划：2012年11月12日-2012年12月2日：按照任务书要求查阅论文相关参考资料，填写毕业设计开题报告书。2012年12月3日-2013年1月20日：专业实训。2013年1月21日-2013年3月1日：毕业实习。2013年3月2日-2010年3月8日：学习并翻译一篇与毕业设计相关的英文材料。2013年3月9日-2013年3月29日：ABS的动力学建模与分析。2013年3月30日-2013年4月26日：用MATLAB/Simulink，搭建框图并进行仿真。2013年4月27日-2013年5月25日：毕业论文撰写和修改工作。预期成果：通过对开关控制、PID控制等方法的研究对其进行进一步的了解和探索，将它们的最新成果应用于ABS系统，使其更加完善的工作于车辆中。特色或创新之处 使用MATLAB编程仿真，效果明显，方便改变参量，能够直观判断实验结果。 采用固定某些参量、改变某些参量来研究问题的方法，思路清晰，简洁明了，行之有效。已具备的条件和尚需解决的问题 实验方案思路已经非常明确，已经具备使用MATLAB编程仿真的能力和图像处理方面的知识。 使用MATLAB编程的能力尚需加强。指导教师意见 指导教师签名：年 月 日教研室（学科组、研究所）意见 教研室主任签名： 年 月 日系意见 主管领导签名： 年 月 日英文原文Brake systemsWe all know that pushing down on the brake pedal slows a car to a stop. But how does this happen? How does your car transmit the force from your leg to its wheels? How does it multiply the force so that it is enough to stop something as big as a car?When you depress your brake pedal, your car transmits the force from your foot to its brakes through a fluid. Since the actual brakes require a much greater force than you could apply with your leg, your car must also multiply the force of your foot. It does this in two ways: Mechanical advantage (leverage) Hydraulic force multiplication The brakes transmit the force to the tires using friction, and the tires transmit that force to the road using friction also. Before we begin our discussion on the components of the brake system, well cover these three principles: Leverage Hydraulics Friction Leverage and HydraulicsIn the figure below, a force F is being applied to the left end of the lever. The left end of the lever is twice as long (2X) as the right end (X). Therefore, on the right end of the lever a force of 2F is available, but it acts through half of the distance (Y) that the left end moves (2Y). Changing the relative lengths of the left and right ends of the lever changes the multipliers. The basic idea behind any hydraulic system is very simple: Force applied at one point is transmitted to another point using an incompressible fluid, almost always an oil of some sort. Most brake systems also multiply the force in the process. Here you can see the simplest possible hydraulic system: Your browser does not support JavaScript or it is disabled. Simple hydraulic system In the figure above, two pistons (shown in red) are fit into two glass cylinders filled with oil (shown in light blue) and connected to one another with an oil-filled pipe. If you apply a downward force to one piston (the left one, in this drawing), then the force is transmitted to the second piston through the oil in the pipe. Since oil is incompressible, the efficiency is very good - almost all of the applied force appears at the second piston. The great thing about hydraulic systems is that the pipe connecting the two cylinders can be any length and shape, allowing it to snake through all sorts of things separating the two pistons. The pipe can also fork, so that one master cylinder can drive more than one slave cylinder if desired, as shown in here: Your browser does not support JavaScript or it is disabled. Master cylinder with two slaves The other neat thing about a hydraulic system is that it makes force multiplication (or division) fairly easy. If you have read How a Block and Tackle Works or How Gear Ratios Work, then you know that trading force for distance is very common in mechanical systems. In a hydraulic system, all you have to do is change the size of one piston and cylinder relative to the other, as shown here: Your browser does not support JavaScript or it is disabled. Hydraulic multiplication To determine the multiplication factor in the figure above, start by looking at the size of the pistons. Assume that the piston on the left is 2 inches (5.08 cm) in diameter (1-inch / 2.54 cm radius), while the piston on the right is 6 inches (15.24 cm) in diameter (3-inch / 7.62 cm radius). The area of the two pistons is Pi * r2. The area of the left piston is therefore 3.14, while the area of the piston on the right is 28.26. The piston on the right is nine times larger than the piston on the left. This means that any force applied to the left-hand piston will come out nine times greater on the right-hand piston. So, if you apply a 100-pound downward force to the left piston, a 900-pound upward force will appear on the right. The only catch is that you will have to depress the left piston 9 inches (22.86 cm) to raise the right piston 1 inch (2.54 cm).A Simple Brake SystemBefore we get into all the parts of an actual car brake system, lets look at a simplified system:Your browser does not support JavaScript or it is disabled. A simple brake system You can see that the distance from the pedal to the pivot is four times the distance from the cylinder to the pivot, so the force at the pedal will be increased by a factor of four before it is transmitted to the cylinder. You can also see that the diameter of the brake cylinder is three times the diameter of the pedal cylinder. This further multiplies the force by nine. All together, this system increases the force of your foot by a factor of 36. If you put 10 pounds of force on the pedal, 360 pounds (162 kg) will be generated at the wheel squeezing the brake pads. There are a couple of problems with this simple system. What if we have a leak? If it is a slow leak, eventually there will not be enough fluid left to fill the brake cylinder, and the brakes will not function. If it is a major leak, then the first time you apply the brakes all of the fluid will squirt out the leak and you will have complete brake failure. Drum brakes work on the same principle as disc brakes: Shoes press against a spinning surface. In this system, that surface is called a drum.Figure 1. Location of drum brakes. See more drum brake pictures.Many cars have drum brakes on the rear wheels and disc brakes on the front. Drum brakes have more parts than disc brakes and are harder to service, but they are less expensive to manufacture, and they easily incorporate an emergency brake mechanism. In this edition of HowStuffWorks, we will learn exactly how a drum brake system works, examine the emergency brake setup and find out what kind of servicing drum brakes need. Figure 2. Drum brake with drum in placeFigure 3. Drum brake without drum in placeLets start with the basics. The Drum BrakeThe drum brake may look complicated, and it can be pretty intimidating when you open one up. Lets break it down and explain what each piece does. Figure 4. Parts of a drum brakeLike the disc brake, the drum brake has two brake shoes and a piston. But the drum brake also has an adjuster mechanism, an emergency brake mechanism and lots of springs. First, the basics: Figure 5 shows only the parts that provide stopping power. Your browser does not support JavaScript or it is disabled. Figure 5. Drum brake in operation When you hit the brake pedal, the piston pushes the brake shoes against the drum. Thats pretty straightforward, but why do we need all of those springs? This is where it gets a little more complicated. Many drum brakes are self-actuating. Figure 5 shows that as the brake shoes contact the drum, there is a kind of wedging action, which has the effect of pressing the shoes into the drum with more force. The extra braking force provided by the wedging action allows drum brakes to use a smaller piston than disc brakes. But, because of the wedging action, the shoes must be pulled away from the drum when the brakes are released. This is the reason for some of the springs. Other springs help hold the brake shoes in place and return the adjuster arm after it actuates. Brake AdjusterFor the drum brakes to function correctly, the brake shoes must remain close to the drum without touching it. If they get too far away from the drum (as the shoes wear down, for instance), the piston will require more fluid to travel that distance, and your brake pedal will sink closer to the floor when you apply the brakes. This is why most drum brakes have an automatic adjuster. Figure 6. Adjuster mechanismNow lets add in the parts of the adjuster mechanism. The adjuster uses the self-actuation principle we discussed above. Your browser does not support JavaScript or it is disabled. Figure 7. Drum brake adjuster in operation In Figure 7, you can see that as the pad wears down, more space will form between the shoe and the drum. Each time the car stops while in reverse, the shoe is pulled tight against the drum. When the gap gets big enough, the adjusting lever rocks enough to advance the adjuster gear by one tooth. The adjuster has threads on it, like a bolt, so that it unscrews a little bit when it turns, lengthening to fill in the gap. When the brake shoes wear a little more, the adjuster can advance again, so it always keeps the shoes close to the drum. Some cars have an adjuster that is actuated when the emergency brake is applied. This type of adjuster can come out of adjustment if the emergency brake is not used for long periods of time. So if you have this type of adjuster, you should apply your emergency brake at least once a week. ServicingThe most common service required for drum brakes is changing the brake shoes. Some drum brakes provide an inspection hole on the back side, where you can see how much material is left on the shoe. Brake shoes should be replaced when the friction material has worn down to within 1/32 inch (0.8 mm) of the rivets. If the friction material is bonded to the backing plate (no rivets), then the shoes should be replaced when they have only 1/16 inch (1.6 mm) of material left. Photo courtesy of a local AutoZone storeFigure 9. Brake shoeJust as in disc brakes, deep scores sometimes get worn into brake drums. If a worn-out brake shoe is used for too long, the rivets that hold the friction material to the backing can wear grooves into the drum. A badly scored drum can sometimes be repaired by refinishing. Where disc brakes have a minimum allowable thickness, drum brakes have a maximum allowable diameter. Since the contact surface is the inside of the drum, as you remove material from the drum brake the diameter gets bigger. The current Bosch component Anti-lock Braking System (ABS), is a second generation design wildly used by European automakers such as BWM, Mercedes-Benz and Porsche. ABS system consists of : four wheel speed sensor, electronic control unit and modulator assembly. A speed sensor is fitted at each wheel sends signals about wheel rotation to control unit. Each speed sensor consists of a sensor unit and a gear wheel. The front sensor mounts to the steering knuckle and its gear wheel is pressed onto the stub axle that rotates with the wheel. The rear sensor mounts the rear suspension member and its gear wheel is pressed onto the axle. The sensor itself is a winding with a magnetic core. The core creates a magnetic field around the winding, and as the teeth of the gear wheel move through this field, an alternating current is induced in the winding. The control unit monitors the rate o change in this frequency to determine impending brake lockup. The control units function can be divided into three parts: signal processing, logic and safety circuitry. The signal processing section is the converter that receives the alternating current signals form the speed sensors and converts them into digital form for the logic section. The logic section then analyzes the digitized signals to calculate any brake pressure changes needed. If impending lockup is sensed, the logic section sends commands to the modulator assembly. The hydraulic modulator assembly regulates pressure to the wheel brakes when it receives commands from the control utuit. The modulator assembly can maintain or reduce pressure over the level it receives from the master cylinder, it also can never apply the brakes by itself. The modulator assembly consists of three high-speed electric solenoid valves, two fluid reservoirs and a turn delivery pump equipped with inlet and outlet check valves. The modulator electrical connector and controlling relays are concealed under a plastic cover of the assembly. Each front wheel is served by electric solenoid valve modulated independently by the control unit. The rear brakes are served by a single solenoid valve and modulated together using the select-low principle. During anti-braking system operation, the control unit cycles the solenoid valves to either hold or release pressure the brake lines. When pressure is released from the brake lines during anti-braking operation, it is routed to a fluid reservoir. There is one reservoir for the front brake circuit. The reservoirs are low-pressure accumulators that store fluid under slight spring pressure until the return delivery pump can return the fluid through the brake lines to the master cylinder. 中文译文制动系统众所周知，踩下制动踏板可以使汽车减速至停止。但这是如何产生的呢？汽车是如何将力从你的腿传递到车轮的呢？汽车是如何将力放大到足够大以致可以将像汽车一样大的东西制动的呢？ 制动系统组件当你踩下制动踏板的时候，汽车通过液体把力从脚传递到制动器。因为制动器需要的真正力量比你的腿能提供的要大的多，所以汽车必须放大脚产生的力 有两种方式：机械杠杆作用液力放大 制动器通过摩擦把力传递给轮胎，并且轮胎也是通过摩擦把力传递给路面的。 在我们讨论制动系统的组成之前，先来介绍以下三条原则：杠杆液力摩擦力杠杆和液力在下面的图中，一个力F加在杠杆的左端。左端的杠杆长度（2X）是右端（X）的两倍。因此杠杆右端可施加的力为2F ，但是右端移动的距离(Y)是左端距离(2Y)的一半。改变杠杆的左端和右端的长度可以改变放大系数。 任何液压系统背后的基本原理都是非常简单的：作用在某一点力通过通常是油一类的不可压缩的液体传递到另一点。大多数的制动系统也在这个过程中放大力。下面的是最简单的液压系统： 简单液压系统在上图中，两个活塞放在两个充满油的玻璃液压缸中并且由充满油的管道相连。如果在一个活塞上施加一个向下的力，那么力将通过管道中的油传递到第二个活塞。因为油液是不可压缩的，所以传递效率很好，大部分的作用力都传递到了另一个活塞。液压系统的好处连接两液压缸的管道可以是任何长度和形状，这样就可以使管道弯曲的通过两活塞之间的各种部件。管道也可以是分叉的，如果有需要的话，这样一个主缸可以驱动数个副缸。如下图所示： 带有两个副缸的主缸 液压系统的另一个好处是产生放大（或者缩小） 力相当地容易。如果你一读过滑车设备工作原理或者齿轮齿数比原理，那么你就会知道在机械系统中把力转化为距离处理是很常见的。在液压系统中，我们所要做的就是相对地改变一组活塞和液压缸的尺寸。如下图所示： 液压增力原理为了确定上图中的放大因子，先由观察活塞的尺寸开始。假设左边活塞的直径为2英尺（5.08cm而右边的直径为6英尺（15.24cm）。两个活塞的面积是Pi * r2 。因此左面活塞的面积是3.14，而右面的面积是28.26。右面活塞的面积是左边的九倍大。这就意味着无论在左面的活塞上施加多大的力，在右面的活塞上就会输出九倍于左面的力。所以，如果在左边活塞上施加100磅向下的力，那么在右面活塞上将产生900磅向上的力。唯一的补偿是左面的活塞要移动9英尺（22.86cm）来使右面提升1英尺（2.54cm）一个简单的制动系统在我们深入了解一个真实的制动系统的各部分之前，让我们先来看一个简化的系统： 我们可以看到踏板到枢轴的距离是液压缸到枢轴距离的4倍，所以施加在踏板上的力在传递到液压缸之前将被增加4倍。我们还可以看到制动缸的直径是踏板缸直径的3倍。这就将力进一步放大了九倍。最终这个系统将腿上的力增加了36倍。所以，如果在踏板上施加10磅的力，将在挤压制动带的轮上产生369磅（162kg）的力。下面是这种简单系统所存在的问题。要是系统有泄漏该怎么办呢？如果是轻微泄漏，最终将会没有足够的油使制动缸充满，并且制动器将停止工作。如果是严重泄漏，那么在你制动的第一时间，所有的油液将从泄露处喷射而出，并且制动系统将彻底地不起作用。鼓式制动器的工作原理和盘式制动器是一样的：制动面接触一个磨砂的表面。在这个系统中，那个表面称作制动鼓 图1.制动鼓的位置许多汽车的后轮安装鼓式制动器，而盘式制动器安装在前面。鼓式制动器比盘式制动器有更多的零件并且更难检修。 但是制造成本相对便宜，还有鼓式制动器容易组装一个紧急使用的制动装置。在本版本的How StuffWorks中，我们将详尽了解鼓式制动系统是如何工作的。考察紧急制动系统的组成，并且找到鼓式制动器需要何种检修工作。图2. 有鼓的鼓式制动器 图3.未安装鼓的鼓式制动器让我们基础开始：鼓式制动器鼓式制动器可能看起来比较复杂，它可以是很复杂的，当你打开一个的时候。让我们拆开它，并解释每一块的作用。 图4. 鼓式制动器的组成如盘式制动器，鼓式制动器有两个制动蹄和一个活塞。 But the drum brake also has an adjuster mechanism, an emergency brake mechanism and lots of springs .但是鼓式制动器也有一个调节机制，紧急刹车机制和大量的弹簧 。首先，基础知识： 图5显示只有部分提供的制动力。 图5.工作状态下的鼓式制动器当你踩下刹车踏板时，活塞推动紧靠着鼓的制动
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