如何使用lis3dx检测车祸中的加速度阈值

你好，
我认为没有人会在这里写出任何车祸的典型值。有这么多变种！这就是汽车制造商和安全系统制造商进行数百万小时测试的原因。
你确定需要高通滤波器吗？如果你消除了重力，你会失去重力方向的感觉，这是不好的。如果汽车在屋顶上翻滚怎么办？这是意外吗？
另外，如果挡泥板弯曲你的意外？大多数挡泥板都是用塑料制成的，它们会影响第一部分的冲击力。这就是为什么通常会嵌入其他传感器，因为时间对于发射安全气囊和安全带等至关重要。
但是，如果您正在构建一些业余爱好项目，那么仅通过实验设置值和时间阈值就足够了。
这是一些阅读：
https://www.wired.com/2011/04/crashing-into-wall/
 大卫



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Hello,
I don't think anyone will write any typical values for a car accident here. There are so many variants! This is why car manufacturers and safety systems manufacturers do millions of hours of testing.
Are you sure you need the high pass filter? If you eliminate the gravity, you loose the sense of the gravity direction and that is not good. What if the car is rolled over a roof? Is that an accident?
Also, if a fender bender an accident for you? Most of the fenders are made from plastic and they soften the first part of the impact. That is why there are usually other sensors embedded, because time is critical in order to fire the airbags and seatbelts, etc.
However, if you are building just some hobby project, it might be sufficient to just experimentally set value and time threshold.
Here is some reading:
https://www.wired.com/2011/04/crashing-into-wall/
David

非常感谢您的输入和阅读材料。他们非常有帮助。
在我的应用程序中事故检测的实时质量并不那么重要，所以毫无疑问。这是一款产品，可以帮助标记相机在发生车祸时拍摄的视频。是的，一辆车在屋顶上滚动绝对是车祸，但即使采用了高通滤波器，lis3dx传感器仍能检测到它，不是吗？
我问高通滤波器设置的原因是因为高通滤波器可以帮助衰减正常汽车驾驶中产生的加速度信号，这在大多数情况下相当温和。高通滤波器也可以帮助去除直流分量。
我还发现，在相同的阈值和持续时间设置下，较低的HPCF设置可以在正常的汽车行驶时更容易导致中断触发。我推断，较低的HPCF会减少正常汽车行驶中产生的信号，并且很容易导致中断触发。



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Thank you very much for your input and reading material. They are extremely helpful.
The real-time quality of the accident detection in my application is not that critical so no question about that. It's a product that help mark the video taken by the camera in case of car accident. Yes, a car rolling over a roof is definitely a car accident but it still can be detected by the lis3dx sensor even if the high pass filter is applied, can't it?
The reason I'm asking about the high pass filter setting is because the high pass filter can help attenuate the acceleration signals generated in normal car driving which is rather gentle in most cases. Also high pass filter can help remove the dc components.
I also find with the same threshold and duration setting, the lower HPCF setting can cause the interrupt trigger more easily in case of normal car driving. I deduce that the lower HPCF attenuate the signal generated in normal car driving less and cause the interrupt trigger easily.

对不起，您是否使用LIS3DH进行冲击检测？我用我的设备轻轻敲击桌子，加速度读数超过8g。



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Excuse me, did you use the LIS3DH for impact detection? I tapped my table lightly with my device and the acceleration readings were over 8g.

你在用什么部分？ 3DH？如果是这样，3DH的输出左对齐为2的互补，它需要右移4位。



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What part are you using? 3DH? If so, the output of 3DH is left aligned in 2's complementary and it needs to be right shifted by 4 bit.

查看ST官方的AN3308了解更多详情。



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Check AN3308 from ST official for more details.

还有，这部分了
http://www.st.com/resource/en/datasheet/lis3dh.pdf
 表示每个范围的每LSB（“数字”）的分辨率：David



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Also, this part of the
http://www.st.com/resource/en/datasheet/lis3dh.pdf
states resolution per LSB (''digit'') for each range:David

非常感谢你花时间回复。值的转换符合手册，并且它们是正确的。平坦时，X轴和Y轴倾向于0，Z轴约为1g。然后，当我进行冲击测试时，我会使用该设备轻轻敲下桌子。有些轴可以检测到10g左右。这有点难以理解。 10g加速度不应该很大。我会点击它以便它可以产生如此大的加速度。这有点困惑，所以我想问你一下。你有没有尝试过这种碰撞测试？



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Thank you very much for taking the time to reply. The conversion of the values is in accordance with the manual, and they are correct. When flat, the X and Y axes tend to be 0, and the Z axis is about 1g. Then I use the device to gently knock down the table when I do the impact test. Some axes can detect 10g or so. It's a bit unintelligible. 10g acceleration shouldn't be very big. I'll tap it so that it can produce such a large acceleration. It's a little puzzled, so I'd like to ask you about it. Have you tried this kind of crash test?

我没有做过这种测试。测试是由您或ST官方设计的吗？无论如何，10g加速度不正常，一定有问题。您可以详细地打开描述该问题的主题。 ST人会尽力帮助你。他们很反应。



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I have not do this kind of test. Is the test designed by you or ST official? Anyway, 10g acceleration is not normal and there must be something wrong. Probably you can open a topic describing the issue in detail. The ST people will try to help you. They are quite reactive.