百科知識視頻之煎蛋小學(xué)堂86 倒車為何那么難

When you turn a car's steering wheel,whether you go forwards or backwards.So it seems like it should be just as easy to steer going backwards as going forwards.But clearly,it's not.Suprisingly,the difficulty of driving backwards has almost nothing to do with the direction you're facing and everything to do with the fact that you steer using the front wheels.

當(dāng)你扭轉(zhuǎn)方向盤，車子都會隨相同的彎曲度運動。所以看起來倒車似乎和前進一樣簡單。但是顯然 事實并非如此。奇怪的是，倒車的困難之處在它幾乎與你對方向盤的控制無關(guān)問題在于你所控制的是車子的前輪。

When driving forwards,a car goes in the direction the front wheels are pointed.And when driving backwards,the car goes where the back wheels are pointed.Simple!But the difference is that going forwards,the direction of travel is determined by the same wheels you steer with,so you just point them where you want to go,and that's where you go,the back wheels follow automatically.

向前行駛時 車子順著前輪的方向前行。而倒車時 車子順應(yīng)的是后輪的方向。很簡單 問題在于，前進時決定方向的車輪與你控制的車輪相同，所以你只要打好方向盤車子就朝你 預(yù)期的方向前進了，后輪會跟著前輪前進。

In physics,we call this a "stable"system.like dangling a pencil from your fingers-move your hand around and the pencil follows,no thought required.However,when driving backwards,the direction of travel is determined by the back wheels but you steer with the front wheels.

在物理中 我們稱之為“穩(wěn)定”系統(tǒng)，就像掛在指尖的鉛筆移動手指它就會跟著動，無需自具想法。但是，在倒車時，決定車子運動方向的是后輪，而你控制的卻是前輪。

So rather than just pointing the front wheels where you want to go,you have to point them in the direction that will get the back wheelsto point in the direction you want to go-it's an additional level of separation before the car does what you want.

與只需控制前輪運動不同，你需要通過控制前輪引導(dǎo)后輪向著你預(yù)期的方向運動。這是控制好車子的附加操作。

And in fact,if you don't make any corrections,then over time the back wheels point farther and farther away from the direction you want to go:instead of following the front wheels,they want to run away!This is an unstable system,like trying to balance a pencil on your fingertip.It's incredibly finicky and requires a ton of coordinated hand-eye feedback to maintain.

事實上，如果你不采取修正措施，隨著時間流失，后輪就會越來越偏離你預(yù)期的方向：不但不隨前輪運動 而且還會失控!這是一個不穩(wěn)定系統(tǒng)，就像嘗試平衡立在指尖上的鉛筆一樣。這相當(dāng)講究，需要不停的進行手眼反饋協(xié)調(diào)來完成。

That's why you constantly have to readjust your steering when driving backwards-mathematically,your car is like an upside-down pencil! Of course,there are some successful rear-steering wheeled vehicles-forklifts,for example,only drive slowly and choose rear-steering for greater control of their forks.

這就是倒車時你需要不斷調(diào)整輪胎方向的原因-數(shù)學(xué)說法就是 你的車就像東歪西倒的鉛筆!當(dāng)然 也有一些很棒的后輪控制轉(zhuǎn)向的車子-例如 叉車，行駛緩慢 并且選擇后輪主控叉子。

But let's go in the other direction and add a TRAILER to your car steering backwards has gained ANOTHER level of difficulty:you use your front wheels to get the back wheels to point in the direction needed to get the TRAILER to point in the direction you want to go.Not complicated enough?It becomes worse the more trailers you add each one adds another level of separation between the direction of your steering and the actual direction of travel.

現(xiàn)在我們加點難度 給車子加個拖車，這下倒車難度又更上一層樓了：你通過控制前輪引導(dǎo)后輪的方向，同時還需要使拖車向預(yù)定方向運動。難度還不夠?增加更多拖車后情況就更糟糕了，每增加一輛拖車就會使實際運動方向更加偏離預(yù)期的運動方向。

Which is why it's nearly impossible to push on one end of a chain or a rope and have the other end go where you want it to,and why you will never,ever blance a flexible rope or chain upright on your finger.which makes backwards driving seem downright easy!

這就是為何將鏈條或繩索的一端置于指尖時你永遠無法控制另一端的運動方向，也是你為何永遠無法令靈活的鎖鏈直立于指尖上的原因。相比之下 倒車真是簡單爆了!