Case Study #1 - Braking Bad
案例研究 1——绝命毒师

Day 4 第四天

Hello, I am Racim Fezoui. I started competing in sim-racing in 2019, won the Big C MX5 Championship (2019), was a race winner in the 24H Series Esports and Sports Car Open series, and was 2nd place finisher in the 2023 PESCC. In real life, I have coached and engineered in Radical US, ADAC GT4, FEL ERCC, and SRO GT4 series. My specialty is to craft motorsports on-track exercises. I dissect elements of vehicle dynamics proper to racing thanks to my vehicle dynamics expertise. After doing the exercises, it's like training a muscle for a sport: you will get better without thinking about it once you hit the track for a race. I sure have seen braking mistakes in my time. Let's go through them.
你好，我是拉西姆·费祖伊（Racim Fezoui）。我于 2019 年开始参加模拟赛车比赛，赢得了大 C MX5 锦标赛（2019 年），在 24 小时系列电竞和跑车公开赛系列赛中获得过冠军，并且在 2023 年 PESCC 中获得了第二名。在现实生活中，我在 Radical US、ADAC GT4、FEL ERCC 和 SRO GT4 系列赛事中担任教练和工程师。我的专长是制定赛车运动的赛道练习。凭借我在车辆动力学方面的专业知识，我剖析适合赛车的车辆动力学要素。完成这些练习后，就像为一项运动锻炼肌肉一样：一旦你参加比赛上了赛道，你会在不经意间变得更好。我在我的职业生涯中确实见过刹车失误。让我们来逐一分析这些失误。

FAST IN, FAST OUT 快进快出

Every corner starts with braking. By the moment you touch the brakes, you are attacking the corner and fighting time. If you brake earlier than the next driver, can you be faster? Absolutely not. Imagine you steer into a corner with the perfect balance, grip and car control: if you brake 20m earlier than your competitor, you are automatically at risk of losing time. There are even cases where you will think sacrificing the entry to throttle early is faster, but it is not always true at all. The goal is not "Slow in, fast out". The goal is Fast in, Fast out.
每个弯道都始于刹车。当你踩下刹车的那一刻，你就在进攻弯道并与时间赛跑。如果你比后面的车手更早刹车，你会更快吗？绝对不会。想象一下，你以完美的平衡、抓地力和车辆操控驶入弯道：如果你比你的竞争对手早 20 米刹车，你自然就有损失时间的风险。甚至有些情况下，你会认为牺牲入弯速度以尽早踩油门会更快，但这根本不总是正确的。目标不是“慢进快出”。目标是<强 id=0>快进快出。

Let us look at the case below from real-life Audi GT4 data. In Figure 4.1, the driver (red) brakes about 10m deeper than his other lap (green). Also, note that he was able to press much harder on the brakes in red than in green. He was able to decelerate faster without locking up or losing brake performance from too much ABS: he was braking more efficiently in the red lap. Therefore, he gains about 0.25s by braking later (Figure 4.2). However, notice that in Figure 4.3 he loses about 0.1s from being 1km/h slower mid-corner. Here is the magic: although he loses time mid-corner, the throttle pick-up is not late enough to lose the entire 0.25s. In the end, in Figure 4.3, even if he is about 5m later on the throttle, the driver gains a total of 0.15s from braking later into the corner: -0.25s from braking deep, and +0.1s from throttling later, which sums to -0.15s. 
让我们从真实的奥迪 GT4 数据中的以下案例来看。在图 4.1中，车手（红色线条表示）的刹车点比他另一圈（绿色线条表示）深了约 10 米。还要注意的是，他在红色线条表示的这一圈刹车时能比绿色线条表示的那一圈更用力。他能够更快地减速，而不会因为防抱死制动系统（ABS）介入过多而抱死或失去刹车性能：他在红色线条表示的这一圈刹车更有效率。因此，他通过更晚刹车（图 4.2）节省了约 0.25 秒。然而，请注意在图 4.3中，他在弯道中段因为车速慢了 1 千米/小时而损失了约 0.1 秒。神奇之处在于：虽然他在弯道中段损失了时间，但油门响应并没有延迟到足以损失全部 0.25 秒。最后，在图 4.3中，即使他踩油门晚了约 5 米，但车手通过更晚刹车入弯总共节省了 0.15 秒：深刹车节省 -0.25 秒，晚踩油门损失 +0.1 秒，总计 -0.15 秒。

Figure 4.1: -0.036s Before Braking. Also, notice the difference in braking trace.
图 4.1：制动前 -0.036 秒。此外，请注意制动轨迹的差异。

Figure 4.2: -0.289s Mid-corner. This means that the driver gained 0.253s during the braking zone.
图 4.2：-0.289 秒中弯。这意味着车手在制动区赢得了 0.253 秒。

Figure 4.3: -0.185s on Exit. The driver was up by 0.253s at the apex and lost 0.104s on exit. The total time gained in this corner is 0.149s. Even though he lost time on exit, he was still faster when braking later. 
图 4.3：出弯耗时 -0.185 秒。车手在弯道顶点快了 0.253 秒，但出弯时损失了 0.104 秒。在这个弯道总共赢得了 0.149 秒的时间。尽管他出弯时损失了时间，但他晚刹车时仍然更快。

The main takeaway is the following: braking later is a tradeoff. If you try to brake late but apply the throttle too late, you can lose more time on exit compared to the gain you will make on entry, resulting in a net loss. It is for you to test out how deep you can get away with late braking with the most minimal compromise on exit possible.
主要的收获如下：晚刹车是一种权衡。如果你试图晚刹车但太晚踩油门，与入弯时获得的优势相比，出弯时可能会损失更多时间，从而导致净损失。你需要测试在尽可能减少出弯妥协的情况下，晚刹车能做到什么程度。

BRAKING EARLY/LATE - DIAGNOSIS
制动过早/过晚 - 诊断

Now, why did you brake too early or too late? There are two main reasons: you are braking under the limit and do not have a reference marker.
现在，你为什么刹车过早或过晚呢？主要有两个原因：你在极限之下刹车，并且没有一个参照标记。

1. Braking Under the Limit
极限下制动

Firstly, you are braking under the limit. If you recall the Threshold Braking chapter, a tire has a brake pressure limit that you apply when driving straight. If you apply more brake pressure than the tire can sustain (i.e. the threshold), the tire will break the grip with the track surface and lock up. However, here is the catch. Racing is about going fast: if you brake under the limit, you will brake sooner than your opponent. If you brake 20m earlier than your opponent, then you lose 20m of flat-out top speed: you will lose time. 
首先，你在极限之下刹车。如果你回忆一下“临界刹车”这一章节，轮胎在直线行驶时有一个刹车压力极限。如果你施加的刹车压力超过轮胎所能承受的（即临界值），轮胎就会失去与赛道表面的抓地力而抱死。然而，这里有个问题。赛车就是要跑得快：如果你在极限之下刹车，你就会比对手更早刹车。如果你比对手早刹车 20 米，那么你就损失了 20 米的全速最高速度：你就会损失时间。

Look at the Figures from the Audi R8 above again. Notice how the same driver on the green lap applied less brake pressure than on the red lap through the braking zone (Figure 4.1). Pay attention: if the driver shifts the green braking to begin at the same point as the red braking, the green car never makes the corner. Why? Simply because since he is braking under the limit, he is not slowing down fast enough. The less you press on the brakes, the more time it takes for the car to slow down, and the longer the braking zone. Therefore, the green car needs to brake earlier because it has a longer braking zone than the red car, and loses time in the process. However, there is a braking limit. If you go beyond the limit, you will also lose braking performance. 
再看一下上方奥迪 R8 的图表。注意，在绿色圈速下的同一名车手在制动区施加的制动压力比红色圈速时要小（图 4.1）。请注意：如果车手将绿色制动的起始点调整到与红色制动相同的位置，绿色赛车就无法过弯。为什么呢？原因很简单，因为他是在<强 id=1>极限之下制动，减速不够快。刹车踩得越轻，赛车减速所需的时间就越长，制动区也就越长。因此，绿色赛车需要更早制动，因为它的制动区比红色赛车长，并且在此过程中会损失时间。然而，制动是有极限的。如果超过这个极限，也会损失制动性能。

Figure 4.4 - If the driver shifts the green braking to begin at the same point as the red braking, the green car never makes the corner. Look at the difference in peak pressure.
图 4.4 - 如果车手将绿色制动（点）调整到与红色制动（点）开始于同一点，绿色赛车就无法转弯。看看峰值压力的差异。

The goal is not to brake over the limit, not under the limit, but at the limit. I would even argue that for a car that does not lock up easily, or for a car with ABS, it is much better to be slightly above the limit than below the limit because a tire can deform: it is better to deform it a bit too much without sliding rather than not load the tire and lose time.
目标不是过度刹车，也不是刹车不足，而是恰到好处地刹车。我甚至认为，对于一辆不易抱死的汽车，或者有防抱死制动系统（ABS）的汽车来说，稍微过度刹车比刹车不足要好得多，因为轮胎会变形：宁可让轮胎过度变形而不滑动，也不要让轮胎不受力而浪费时间。

2. Reference Marker 2. 参考标记

Secondly, you do not have braking references. 
其次，你没有<强 id=0>制动参考。

Braking markers are any stationary items around the racetrack such as number boards, marshal posts, a nice tree, a sponsor board, cracks or tarmac changes on the track, and any other item that does not move as laps are turned. The last part is the most important: the marker cannot change places throughout your session. Therefore, you cannot use shadows as a braking marker. For example, I used a shadow for braking at the bus stop at Spa and felt like an idiot when I realized that I forgot that the sun does not exist at night and that my shadow braking marker disappeared.
刹车标记是赛道周围任何静止的物体，例如号码牌、指挥站、一棵漂亮的树、赞助商广告牌、赛道上的裂缝或柏油路面的变化，以及在跑圈过程中不会移动的任何其他物体。最后一点是最重要的：在整个赛程中，标记的位置不能改变。因此，你不能将阴影用作刹车标记。例如，我在斯帕赛道的公交车站弯道（bus stop）利用阴影来刹车，当我意识到自己忘了晚上没有太阳，我的阴影刹车标记消失了的时候，我觉得自己像个傻瓜。

Why is a braking reference important? It allows you to measure how deep you need to brake to make a corner. You can experiment with braking earlier and later. It will help you find out where to brake to best take a corner, and it will help you repeat your braking motion to be more consistent. It will also help you vary your braking point depending on fuel load, grip level, hot vs. cold conditions, etc. 
为什么<强 id=0>制动参考很重要？它能让你衡量过弯时需要制动到什么程度。你可以尝试早一点或晚一点制动。这将有助于你找出在哪里制动能最好地过弯，并且有助于你重复制动动作以使其更加一致。它还将有助于你根据燃油负载、抓地力水平、冷热状况等因素改变制动点。

Figure 4.5 - Braking marker on the side of the track at Watkins Glen
图 4.5 - 沃特金斯格伦赛道一侧的刹车标记

HOW TO CORRECT BAD BRAKING (EXERCISES)
如何纠正不良刹车（练习）

1. Braking Limit 制动极限

To begin with, you need to know what braking at the limit feels like. I believe that what you feel is based on your senses. I have observed that the car will give you cues for any time it will breach grip through your senses.
首先，你需要知道极限刹车是什么感觉。我认为你的感觉基于你的感官。我观察到，汽车会通过你的感官在任何即将失去抓地力的时候给你提示。

Here is my exercise on how to correct threshold braking:
以下是我关于如何正确进行临界制动（门槛制动）的练习

1. Go on track. If you have the choice, choose a track with a lot of straightaways. I always recommend the Monza Junior layout for this exercise.
1. 进入赛道。如果可以选择的话，选择一条有很多直道的赛道。对于这项练习，我总是推荐蒙扎青少年赛道布局。

2. Gradually load the brakes until you reach a pressure high enough to almost breach the grip. Do it way before the corner so you can still make the corner safely if you mess up your braking. Also, make sure that there is nobody behind you. Moreover, for REAL LIFE drivers, do not breach the grip on tires you need for future sessions. Instead, get as close to breaching the grip. Keep increasing the pressure until you feel something different in the car. Your goal is to train yourself to spot the different cues you get from breaking grip under braking: 
2. 逐渐踩下刹车，直至达到足以几乎突破抓地力的压力。在入弯前就进行操作，这样的话，如果你刹车失误，仍能安全过弯。此外，要确保身后没有车辆。再者，对于现实生活中的驾驶员来说，不要突破后续行程所需轮胎的抓地力。而是要尽可能接近突破抓地力的状态。不断增加压力，直至感觉到车辆有异样。你的目标是训练自己识别刹车时突破抓地力所得到的不同信号： 

CUES 
提示 

• Eyes: If you look at the apex through your entire braking zone (as you should), your eyes will measure deceleration. Moreover, your peripheral vision will spot ABS lights or slip lights in cars mounted with them. 
  眼睛：如果你在整个刹车区间都看着顶点（你应该这么做），你的眼睛将能感知减速情况。此外，你的周边视觉将能发现安装了防抱死制动系统（ABS）指示灯或防滑指示灯的汽车上的这些指示灯。 
• Touch: There is a light steering vibration feeling as the tires are about to lock. It is light, but present, so if you practice paying attention to it, you will correct your brake pressure before your tires lock. In some cars, front wheel locking or ABS at the front axle can be felt through the steering wheel. In a car without ABS, you will feel the steering wheel go light in the direction of lockup. ABS will be felt as vibrations in the steering wheel in cars where the power steering does not impact vibrations. Some cars have a power steering too high to feel ABS vibrations. In most modern GT cars, the ABS is not well felt through the pedal. In road cars or less performant GT cars, however, you can feel the pedal pulse from the ABS engaging.
  触感：当轮胎即将抱死时，会有轻微的转向震动感。这种感觉很轻微，但确实存在，所以如果你练习留意这种感觉，就会在轮胎抱死之前调整刹车压力。在一些汽车上，可以通过方向盘感受到前轮抱死或前轴的防抱死制动系统（ABS）。在没有 ABS 的汽车中，你会感觉到方向盘在抱死方向上变轻。在助力转向不影响震动的汽车中，ABS 会被感觉为方向盘的震动。有些汽车的助力转向力度太大，以至于无法感受到 ABS 震动。在大多数现代高性能跑车（GT cars）中，通过踏板不太能明显感觉到 ABS。然而，在普通轿车或性能较低的高性能跑车中，你可以感受到 ABS 启动时踏板的脉动。
• Sound: Tires will make a specific sound when they are about to lock up. Tires also make a different noise when they lock up, but at that point, it is too late. For cars with really loud engines, it can be difficult to hear. Thankfully, for rear-wheel-drive cars, you can hear the rear tires slipping as you apply brake pressure: it will sound as if the engine is mumbling because the drive axle's tires are slipping.
  声音：轮胎即将抱死时会发出一种特定的声音。轮胎抱死时也会发出不同的噪音，但到那时就为时已晚了。对于发动机声音非常大的汽车来说，可能很难听到（这种声音）。幸运的是，对于后轮驱动的汽车，当你施加制动压力时，你能听到后轮在打滑：这听起来就好像发动机在咕哝，因为驱动轴的轮胎在打滑。
• Feel: In real life, load is applied to your body when you brake. If you look at your corner and start braking, notice the amount of G Forces (load) your body is taking. When braking, your body weight shifts forward: it is very similar to water in a cup. Your body feels the pressure from the belt and seat holding you. When you lock up, the car slows down with less load: your body will feel this reduction in load. For ABS, the same occurs. However, it is much more subtle because there is much less load reduction with ABS than with a complete tyre lockup. 
  感受：在现实生活中，当你刹车时，你的身体会承受负荷。如果你看着弯道并开始刹车，注意你的身体所承受的重力（负荷） 大小。刹车时，你的身体重心会向前移：这就和杯子里的水很相似。你的身体能感受到安全带和座椅对你的压力。当你抱死刹车时，汽车减速时负荷较小：你的身体会感受到这种负荷的减小。对于防抱死制动系统（ABS）来说，情况也是如此。不过，这种感觉要微妙得多，因为与轮胎完全抱死相比，ABS 制动时负荷的减小要小得多。

3. Once you have recognized that you have breached grip through one or more of the cues above and others, 
3. 一旦你意识到自己通过上述一种或多种提示以及其他方式失去了抓握（力），

2. Braking Reference 
2. 制动 参考 

This will probably be the only time you will love math if you hate it. My simple exercise to obtain a reference marker is to do, what I call, a difference of distances. Here are the steps:
如果你讨厌数学，这可能将是你唯一会爱上它的时候。我获取参考标记的简单操作是，进行我所谓的“距离差”计算。步骤如下：

0. Learn to brake at the limit in a straight line. Do the brake limit exercise mentioned above. If you brake under the limit, your braking reference will be much earlier than where it is supposed to be. 
0. 学会在直线行驶时极限刹车。进行上述提到的极限刹车练习。如果你在极限之下刹车，你的刹车参考点会比应有的位置早很多。

1. Choose a braking reference waaaaayy before the reference you think (or everyone else) is the actual reference. Do not panic, it is on purpose. 
1. 在你认为（或其他人认为）的实际制动参考点之前很久就选择一个制动参考点。不要惊慌，这是有意为之的。

2. Let's say you chose the 400 board although you feel like the car should brake at the 225 (i.e. a bit before the 200 board), still brake hard and focus on your corner. 
2. 假设你选择了 400 号板，尽管你觉得赛车应该在 225 号（即在 200 号板之前一点）处刹车，仍然要大力刹车并专注于过弯。

3. Here is the magic: once you feel like the car is at a speed low enough to commit to the corner, keep a mental note of which board you are at that very specific moment. For example, if you feel like the car is ready to turn in at the 150 marker (i.e. between 200 and 100), keep a mental note of this marker.
3. 神奇之处在于：一旦你感觉车速已经足够低，可以转弯了，就在心里记住在那个特定时刻你所在的指示牌。 例如，如果你感觉汽车在 150 标记处（即在 200 和 100 之间）就可以转弯了，那就记住这个标记。

4. Do math. You braked at the 400 board. You felt like the car could turn at the 150 board. However, you are 150m away from the corner. Therefore, brake 400-150 = 250m before the corner. BUT BEFORE YOU DO SO,  read step 5.
4. 进行计算。你在<强 id=0>400 米牌处刹车。你感觉汽车能在<强 id=1>150 米牌处转弯。然而，你距离弯道还有 150 米。<强 id=2>因此，在弯道前 400 - 150 = 250 米处刹车。<强 id=3>在弯道前。<强 id=4> 但在你这么做之前，<强 id=5> 阅读第 5 步。

5. I am not crazy, I want you to be safe and not miss the corner: build confidence towards the 250 board. This means you brake once at 400, once at 350, once at 300, once at 275, once at 260, once at 255, etc. If you are on a sim and do not care about crashing, you can argue to send it to the 250 board straight away. However, just keep in mind that it is much easier to build towards a good habit than to get rid of a bad habit. It is much easier to build towards a deep braking reference than to move a "too-deep" braking reference earlier.
5. 我没疯，我希望你安全，不要错过弯道：建立对 250 板（此处可能是特定概念，按原文保留）的信心。这意味着你在速度为 400 时刹车一次，350 时一次，300 时一次，275 时一次，260 时一次，255 时一次，等等。如果你在模拟器上并且不在乎撞车，你可以主张直接冲向 250 板。然而， 要记住，养成好习惯比改掉坏习惯容易得多。建立深度刹车参照比将“过深”的刹车参照提前要容易得多。

Braking is the start of your corner: if you are the best driver on the brakes, you are already gaining time before the corner even happens.
刹车是过弯的开始：如果你是刹车方面最优秀的车手，那么在入弯之前你就已经在争取时间了。