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I'm looking for a low-power weight sensor which can withstand impacts of up to 1000 pounds. Is there a go-to supplier or brand for this sort of product? I want it to give its output digitally; my end goal is to have it implanted in a punching dummy and send data to a Raspberry Pi.

Thank you.

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  • $\begingroup$ Sounds like you need a strain gauge? (and appropriately designed mounting...) $\endgroup$ – Jonathan R Swift Nov 29 '18 at 13:05
  • $\begingroup$ Thanks for the reply Jonathan. I'm considering disassembling cheap kitchen/bathroom scales in order to get a grasp on the way the sensor works. Do you think their scales have a fast enough response time? I feel like usually they take a few seconds to produce any reading at all - let alone multiple readings a second in the case of a striking target. $\endgroup$ – KuboMD Nov 29 '18 at 13:13
  • $\begingroup$ Cheap bathroom scales use strain gauges! (typically as a pre-packaged load cell). The response time is down to the signal processing, not the sensor. Have a watch of this - you can use the raspberry pi to read the voltage difference directly, and the response time will only be limited by your code. youtube.com/watch?v=lWFiKMSB_4M $\endgroup$ – Jonathan R Swift Nov 29 '18 at 13:32
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    $\begingroup$ You have not given a time specification in your question... $\endgroup$ – Solar Mike Nov 29 '18 at 13:33
  • $\begingroup$ Thanks Jonathan! I'll look into that. Mike, you're correct, although it would be implied due to the nature of the application that one does not typically leave their fist on the target after striking. $\endgroup$ – KuboMD Nov 29 '18 at 14:00
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You are actually looking for a force sensor, of which the mentioned strain gauge is one type.

But if you are trying to measure punches, then you need to have a sensor with enough bandwidth to track the applied force on a millisecond basis (at least). For example, the entire punching bag can tell you the total transferred energy, i.e. integral of force over time, simply by applying pendulum equations. But that will not tell you much of anything about the momentary peak force applied.
Next problem is that punching bags are soft, so the force is quickly dispersed from the impact area (fist cross-section) to a much wider area. You probably will have to mount the sensing element on a small rigid plate on the surface of the bag to get an accurate force (pressure times area) reading.

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  • $\begingroup$ Carl, thank you for your input. I should also add that I am not necessarily concerned with getting an "accurate" reading in terms of weight, so long as the readings are consistent. i.e. I want to measure the force of strikes against other strikes; if that means using some seemingly arbitrary metric as opposed to weight then I've no complaints. $\endgroup$ – KuboMD Nov 29 '18 at 19:54

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