Measuring Low Speed with Cellphone 1

[BUGGAR]

I have to design some shock bumpers to stop an 8000 pound X-Ray machine that has to be repositioned frequently to accommodate odd-shaped parts. We will move it on air bearings.
But I will need some means of knowing how fast this thing may move. Before I come up with a fancy engineered solution for measuring how fast this thing is moving, can I just put a cell phone on top of it with the right app and get the speed directly? I’m tentatively looking at a maximum speed of 3 inches per second. Acceleration doesn't matter. I tried asking some young techno people but they didn’t really understand physics so they couldn’t help. The shock bumper reduces the g’s to stop this thing so I can figure that but I need to know the speed based on actual tests.

I’m designing the shock bumpers using auto shock absorbers. There’s a race shop down the street with a shock dyno and a huge supply of used but still good racing shocks. I’ll submit my calculations for this shortly for everyone's critique. I think I can use a shock out of a SCCA Class D Modified, whatever that is.

Thanks all.

 

[GregLocock]

The maximum speed seen on a shock in a car is 240 ips. Our shocks are routinely calibrated to 60 ips, we can double that if necessary (the high velocty behavior is pretty linear until the shock cavitates)

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376

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[TheTick]

GPS won't do.

Every smart phone has a 3-axis accelerometer, and some apps take advantage of it. Most phones have a seismometer app available which will illustrate capabilities.

 

[KENAT]

Didn't thoroughly read this but isn't the problem more that cell phone GPS isn't good for measuring speed over short distances rather than that they aren't good at measuring low speeds? This is a function of the limited resolution with which displacement is measured.

Posting guidelines faq731-376

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(probably not aimed specifically at you)
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[BUGGAR]

We solved the problem without having to measure speed or acceleration.

At 3DDave's suggestion, I visited Arduino territory. This is paradise! I need another lifetime to play with this stuff.

 

[3DDave]

Arduinio is cool. It gets a lot of flack from those who like to lay out their own circuit boards, design their own power supplies, create their own compilers or buy expensive commercial ones. But if you just need something that can get plugged in, programmed by mostly copying and pasting, and be on with it, the Arduino ecosystem has you covered.

 

[Strong]

"We solved the problem without having to measure speed or acceleration."
Care to mention how?
I did mention Arduino in the first response.

Walt