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万向节死锁和阿波罗13号

Gimbal Lock and Apollo 13

看过《阿波罗十三号》的小伙伴们
Those who followed my Apollo 13 lives
也许会注意到万向节死锁出现了好几次
who probably saw the phrase gimbal lock pop-up a number of times,
许多人问我那是什么
and a lot of you asked me what it is.
所以今天我们就来看一看万向节死锁到底是什么
So today I’m venture space we’re looking at what exactly is gimbal lock.
什么是万向节死锁
What is “Gimbal Lock”?
在我们回答关于万向节死锁的问题之前
So we need to break this one down just a little bit
我们需要把它拆下来
before getting into the question of gimbal lock.
在阿波罗制导系统计算机的中心
At the heart of the Apollo guidance computer
有一个惯性测量装置 也就是IMU
was an inertial measurement unit or IMU.
这个装置有一个球形的外壳 大小和足球差不多
The IMU is a spherical housing about the size of a soccer ball
内部有三个嵌套的万向节
that contains three nested gimbals
其中两个以直角的方式互相连接后
They’re set at right angles from one another,
被支撑安装在最里面的万向节中心平台上
supporting a central platform mounted on the innermost gimbal.
外部的万向节安装在航行盘上
The outer gimbal is mounted on the navigation base
这个直接与宇宙飞船相连
and this is mounted rigidly to the spacecraft.
每当宇宙飞船启动
Every time the spacecraft moves
或者每当惯性测量装置探测到一点点角度的改变时
or rather every time the IMU detects any kind of change of attitude,
两组发动机会作用于回转仪 以确保平台回到其初始取向
the gyro is signaled two motors return the platform to its original orientation.
所以当宇宙飞船绕月航行的时候
So as the spacecraft moves around on its path the moon,
内部的制导平台始终保持稳定
the guides platform inside remain stable.
制导平台在起飞前与地面保持平行
The guidance platform was aligned on the ground before the flight
当然 在任务过程中会间或发生漂移
and of course it would drift occasionally during the mission
为了抵消这种漂移 宇航员会依靠平台的
to compensate for this drift astronauts would rely on the platform
导航星观测
using star sighting.
但是它的作用依然存在 依然能给宇航员关于他们在太空中所处位置的信息
But its use still remained and it still gave the astronauts information on their attitude in space.
这些来自达罗的信息会显示在航空地平仪上
The information from these Darrow’s was displayed on the flight director attitude indicator,
也就是俗称的第八球
more commonly known as the eight ball.
所以 实际上惯性测量装置里有三个陀螺仪
So it’s the fact that there are three gyros
这才能保证万向节锁正常使用
involved in the IMU that make gimbal lock possible.
这三个万向节负责宇宙飞船动力的三个轴
The three gimbals account for the spacecraft’s three axis of motion,
也就是俯仰轴 倾斜轴 侧滑轴
motion it’s axis of pitch, yaw and roll,
因为惯性测量装置是测量物体三轴姿态角的
because the IMU works in all three directions,
所以任何姿态角的改变都会被记录在第八球上
any change in the attitudes orientation at all is registered on the eight ball.
关于这三个轴的恒定角度信息
The constant attitude information about these three axes
可以给予宇航员关于其在太空中位置的准确信息
gives the astronaut a very keen sense of exactly where they’re pointing in space,
但也有弊端
but it’s also something that you can lose.
万向节死锁的现象是当最外面的万向节
The phenomenon of gimbal lock is one where in the outer gimbal
跟随宇宙飞船移动
moves with the spacecraft to a point
直到与内部的万向节保持平衡时出现的
where it lies parallel to the inner gimbal.
在这个位置上 三条万向节轴将会全部对准
At this point all three gimbal axes would be lined up on a single plane
谁也不能绕基础平面运行
and none would be able to move around the basic plane
以回到正常定向
to resume normal orientation.
简而言之 如果万向节全部对准
In short, once the gimbals are lined up,
那么它们不能进行重组 也不能为你定向
they can’t realign themselves to give you an orientation
它们就锁死了
and they become locked.
当三个角度的万向节汇合时
It’s the confluence of three angles of the gimbals
万向节就会被锁死
that creates gimbal lock
以防止它们移动进而改变这种状况
and prevents them from moving around to get out of that situation.
阿波罗制导系统计算机在三个万向节将要对准的时候
The Apollo guidance computer was actually designed to prevent gimbal lock
会给宇航员警示
by giving the astronauts a warning
以避免死锁
when they approached that devastating alignment.
然而 依然有可能死锁
However, it was possible still to fall into gimbal lock.
这也就是《阿波罗十三号》发生的事情
This was what was happening on Apollo 13
当宇宙飞船大幅度的俯仰 倾斜的时候
when the spacecraft was wildly pitching and yawing
会导致氧气瓶爆炸
around in the wake of the oxygen tank explosion,
这也就是在电影中
and that is why you hear in the movie and read in the
以及宇航员日志中出现宇航员看着万向节一点点锁死时愤怒喊叫的场景
transcript astronauts yelling about watching the gimbals.
在宇宙中迷失角度使阿波罗十三号
Losing their attitude in space would have made the entire situation on Apollo 13
雪上加霜
just that much worse.
防止万向节死锁最简单的办法
The simplest way to avoid gimbal lock would
就是在惯性测量装置中加入第四个万向节
have been to add a fourth gimble into the IMU,
以增加一个参考点
just giving it another reference point,
这样第四个万向节就不会与前面三个对准
so that the four wouldn’t be able to align the same way.
这也是麦克·柯林斯搭载阿波罗十一号进行绕月时
This is what Mike Collins actually asked for Christmas jokingly
对圣诞老人开玩笑许愿的事情
when he was orbiting the moon on Apollo 11.
他在指挥舱里
From his orbital vantage point in the command module,
慢慢的向飞行器表面的登月舱靠拢
it calls us trying to find the lunar module eagle on the surface,
但是每一次万向节将要被锁死的时候
but every time he got close to gimbal lock,
他就得停下
he had to stop
这也就是他为什么希望宇宙飞船上能有第四个万向节
and that’s why he wished he’d had a fourth gimble on board.
我希望我解释清楚了什么是万向节死锁
So I hope that clears up gimbal lock for you guys,
如果没有的话 请在下面留下你的问题 我会尽力回答
if not, leave question below and I’ll try my best to answer it,
但是我也想给你们推荐两本相关书籍
but I also want to give you two quick book recommendations of things
或许它们能解释的更加细致
that would maybe explain it in a lot more detail.
第一本是弗兰克·欧·布里安的《阿波罗制导系统计算机》
The first is Frank O’Brien’s the Apollo Guidance Computer
它事无巨细的解释了关于
which is everything you ever slashed never wanted to know
阿波罗制导计算机的所有事情
about the Apollo guidance computer
它是一个非常棒的资源
and it is a brilliant resource,
第二本是戴夫·伍兹的《阿波罗是如何飞到月球的》
and the second is How Apollo Flew to the Moon by Dave woods,
它的内容与题目高度契合
it is exactly what the title says,
里面描写了阿波罗登月包括制导计算机的所有细节
it is the details of how Apollo flew to the moon including the guidance computer,
它们都是由著名作家写的惊世之作
both are fantastic resources by excellent authors
如果你们对阿波罗登月的各种小细节比如角度控制 空间隔离等细节感兴趣的话
and I would highly recommend it if you guys want all the nitty-gritty details
我强烈推荐这本书
on things like attitude control and space on Apollo.
和往常一样
So as always,
在评论区留下
leave any questions, comments, and ideas
你想在下一集看到的东西的
for things you’d like to see covered in future episodes
任何问题 评论和意见
in the comment section below.
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and with new episodes going up every Tuesday and Friday.
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Be sure to subscribe right here,
这样就不会错过啦
so you never miss an episode.

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视频概述

万向节死锁的形成

听录译者

survivor

翻译译者

风吹桃

审核员

审核员 W

视频来源

https://www.youtube.com/watch?v=OmCzZ-D8Wdk

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