采纳后加高分！ 牛
看了一下，帮你吧，一级没有什么积分很正常，所以不要以分的多少来决定回不回答，百度知道应该成长为一个互帮互助的平台
E文：
What is an accelerometer?
An accelerometer is an electromechanical device that will measure acceleration forces. These forces may be static, like the constant force of gravity pulling at your feet, or they could be dynamic - caused by moving or vibrating the accelerometer.
What are accelerometers useful for?
By measuring the amount of static acceleration due to gravity, you can find out the angle the device is tilted at with respect to the earth. By sensing the amount of dynamic acceleration, you can analyze the way the device is moving.
At first, measuring tilt and acceleration doesn't seem all that exciting. However, engineers have come up with many ways to make really useful products using them.
An accelerometer can help your project understand its surroundings better. Is it driving uphill? Is it going to fall over when it takes another step? Is it flying horizontally or is it dive bombing your professor? A good programmer can write code to answer all of these questions using the data provided by an accelerometer. An accelerometer can help analyze problems in a car engine using vibration testing, or you could even use one to make a musical instrument.
In the computing world, IBM and Apple have recently started using accelerometers in their laptops to protect hard drives from damage. If you accidentally drop the laptop, the accelerometer detects the sudden freefall, and switches the hard drive off so the heads don't crash on the platters. In a similar fashion, high g accelerometers are the industry standard way of detecting car crashes and deploying airbags at just the right time.
How do accelerometers work?
There are many different ways to make an accelerometer! Some accelerometers use the piezoelectric effect - they contain microscopic crystal structures that get stressed by accelerative forces, which causes a voltage to be generated. Another way to do it is by sensing changes in capacitance. If you have two microstructures next to each other, they have a certain capacitance between them. If an accelerative force moves one of the structures, then the capacitance will change. Add some circuitry to convert from capacitance to voltage, and you will get an accelerometer. There are even more methods, including use of the piezoresistive effect, hot air bubbles, and light.
What things should I consider when buying an accelerometer?
Analog vs digital - First and foremost, you must choose between an accelerometer with analog outputs or digital outputs. This will be determined by the hardware that you are interfacing the accelerometer with. Analog style accelerometers output a continuous voltage that is proportional to acceleration. E.g. 2.5V for 0g, 2.6V for 0.5g, 2.7V for 1g. Digital accelerometers usually use pulse width modulation (PWM) for their output. This means there will be a square wave of a certain frequency, and the amount of time the voltage is high will be proportional to the amount of acceleration.
If you are using a BASIC Stamp, or any other microcontroller with purely digital inputs, you will most likely need to go for a digital output accelerometer. The disadvantage here is that it requires you to use the timing resources of the microcontroller to measure the duty cycle, as well as performing a computationally intensive division operation.
If you are using a PIC/AVR/OOPIC/Javelin with analog inputs, or a completely analog based circuit, analog is almost always the best way to go. Depending on the compiler, measuring analog acceleration can be as simple as acceleration=read_adc(); and can be done in a few microseconds.
Number of axis - For most projects, two is enough. However, if you want to attempt 3d positioning, you will need a 3 axis accelerometer, or two 2 axis ones mounted at right angles.
Maximum swing - If you only care about measuring tilt using earth's gravity, a ±1.5g accelerometer will be more than enough. If you are going to use the accelerometer to measure the motion of a car, plane or robot, ±2g should give you enough headroom to work with. For a project that experiences very sudden starts or stops, you will need one that can handle ±5g or more.
Sensitivity - Generally speaking, the more sensitivity the better. This means that for a given change in acceleration, there will be a larger change in signal. Since larger signal changes are easier to measure, you will get more accurate readings.
Bandwidth - This means the amount of times per second you can take a reliable acceleration reading. For slow moving tilt sensing applications, a bandwidth of 50Hz will probably suffice. If you intend to do vibration measurement, or control a fast moving machine, you will want a bandwidth of several hundred Hz.
Impedance/buffering issues - This is by far the single most common source of problems in projects involving analog accelerometers, because so few people thoroughly read the required documentation. Both PIC and AVR datasheets specify that for A-D conversion to work properly, the connected device must have an output impedance under 10kΩ. Unfortunately, Analog Devices' analog accelerometers have an output impedance of 32kΩ. The solution to this is to use a low input offset rail to rail op amp as a buffer to lower the output impedance. As far as we know, the DE-ACCM is the only accelerometer solution that takes care of this problem for you.
翻译：
什么是加速度？ <br>加速度计是机电设备，将测量的加速度力量。这些部队可能是静态的，如重力固定在你的脚下拉力，或者也可以是动态的 - 通过移动或震动的加速度引起的。 <br> <br>什么是加速度计有用吗？ <br>通过测量静态重力加速度量，您可以找出该设备方面倾斜地球在角度。通过检测的动态加速量，您可以分析该设备的方式移动。 <br>起初，测量倾斜和加速似乎并不很令人激动。但是，工程师们想出了许多办法，使他们真正有用的产品使用。 <br> <br>加速度计可以帮助你的项目更好地了解它的周围。它是驾驶上山？是否要摔倒时，另需一步？它是飞行水平，还是俯冲轰炸你的教授？一个好的程序员可以编写代码来回答这些利用加速计提供的数据的所有问题。加速度计可以帮助分析问题，在汽车发动机利用振动测试，或者你甚至可以使用一个，使一乐器。 <br> <br>在计算领域，IBM和苹果公司最近已经开始使用他们的笔记本电脑加速度来保护硬盘不受损坏。如果你意外地下降了笔记本电脑，突然自由落体加速度计检测，硬盘驱动器和开关关闭，因此不首脑在盘片崩溃。类似地，高g加速度计的行业检测和部署车祸在适当的时候安全气囊的标准方式。 <br>如何加速计的工作？ <br>有许多不同的方法来进行加速！有些加速度计使用压电效应 - 它们包含的微观晶体，得到了加速的力量，这将导致电压强调结构的产生。另一种方式来做到这一点是通过检测电容的变化。如果你有两个彼此相邻微观结构，它们之间有一定的电容。如果一个加速的力量一起移动的建筑之一，则电容会发生变化。增加一些电路，从电容转换成电压，您将获得一个加速度。甚至有更多的方法，包括压阻效应，热气泡使用，轻。 <br> <br>什么东西时，我应该考虑购买一加速度？ <br>相较于模拟数字 - 首先，你必须选择一个与模拟输出或数字输出加速计。这将取决于你的硬件接口与加速度。模拟式加速度计的输出电压，连续加速度成正比。例如为0克为2.5V，2.6V的为0.5克，2.7为1克。数字加速度计通常用于其输出脉冲宽度调制（PWM）。这意味着将会有一个一定频率的方波，和时间的金额将高电压成正比的加速量。 <br> <br>如果您使用的是基本印花税，或任何其他纯数字输入微控制器，你很可能需要去一个数字输出加速计。这里的缺点是，它要求使用微控制器的资源来衡量的时间占空比，以及执行计算密集的除法运算。 <br> <br>如果您使用的是PIC的/的AVR / OOPIC /与模拟输入，或一个完全基于模拟电路标枪，模拟几乎总是最好的一段路要走。根据不同的编译器，测量模拟加速度可高达加速度= read_adc（）简单，并可以在几微秒的工作。 <br> <br>数轴 - 对于大多数项目，二是不够的。不过，如果你想尝试三维定位，你将需要一个3轴加速度计，2轴或两成直角的安装。 <br> <br>最大摆动 - 如果你只关心测量倾斜使用地球的重力，加速度为± 1.5克将绰绰有余。如果你要使用的加速度测量汽车运动，飞机或机器人，± 2克应该给你足够的空间，可工作。对于一个项目的经验非常突然启动或停止时，你会需要一个可以处理± 5克或更多。 <br> <br>敏感性 - 一般来说，越灵敏度越好。这意味着，对于一个给定的加速度变化，将会有一个较大的信号变化。由于更大的信号变化是比较容易衡量，你会得到更准确的读数。 <br> <br>带宽 - 这意味着每秒多少次你可以采取一个可靠的加速度阅读。滞销倾斜感应应用，工频带宽将可能就够了。如果您打算做振动测量，或控制一个快速移动的机器，你会想要一个几百赫兹的带宽。 <br> <br>阻抗/缓冲的问题 - 这是迄今为止最常见的模拟加速计项目涉及问题的根源，因为很少有人仔细阅读所需要的文件。 PIC和AVR的数据表都指定为AD转换到正常工作，根据连接的设备必须有一个输出阻抗10kΩ的。不幸的是，ADI公司的模拟加速度计有一个32kΩ输出阻抗。该方法就是使用一个低输入失调轨到轨作为缓冲，以降低输出阻抗运算放大器。据我们所知，德的ACCM是唯一的解决方案，采用加速度计为你这个问题的照顾。
