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rcralston
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I am working on a project that uses and accelerometer/gyro and arduino to gather data inside of a baseball to measure the velocity and spin rate. I am wanting to push this data to a smartphone app or website. I have started by using bluetooth, but I am wondering if there are other possible routes to take ( wi-fi, RFid). Anything will help!

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Given the forces at play here, wouldn't the arduino just shatter after the first proper hit?

Since you're already putting something inside the ball it's clear you can open it up. Why not put a mini usb stick in there to record the data.

Hasn't the arduino got some local on-board storage?

If only the accelerometer goes inside the ball, well, then you're limited to whatever it can provide.

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Wow 12'000G forget about that!

http://www.acs.psu.edu/drussell/bats/impulse.htm

MEMS Gyro (The kind used in small electronic devices) can sustain 1000G max. Other than that you are looking at rocket grade Gyro and good luck finding that, well let me know if you do find one ;)

I think the proper way to calculate speed and angular momentum would be using a high speed camera and mark the ball in a way you can extract reference from still frame and compare them over time.

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Recap: You're having a baseball made that will contain a gyro hooked up to an arduino board. They will collect data on the ball and you need a way of getting the data out. Since it's a closed package resembling a regular ball in all relevant ways (so no externally accessible ports and no way of directly accessing the board without opening up and thus destroying the ball - which would be bad). So the only way is wireless. You've already investigated the possibility of using Bluetooth and are currently investigating alternatives.

First and obvious question is why you want to step away from Bluetooth? Problems with the speed? Distance? Price of a dongle? Weight of a dongle?

Second obvious question is, since the thing doesn't have any externally accessible ports, how are you going to power/recharge the device?

As for going with Wifi, sure, that's doable. You'll probably be limited to one of those mini wireless adapters which will of course mean next to no antenna and thus very poor transmission power. All that means is you simply need a decent and preferably somewhat directional receiver. That's doable, without breaking the bank. I'm just worried the populated USB port will snap off due to the additional weight and the stresses placed on the device, but I'm sure you've considered that already. I don't know to what extent the ball itself will hinder any signal coming out.

I guess the only thing you can do is try. I don't see any obvious problems. Get that mini wifi adapter for $5.35 and make a Wok-fi antenna from a fine metal mesh collander ($1), a USB wifi adapter for $7.50, a USB extension cord for $2.15 and some glue and have at it. Total cost is under $20 so that shouldn't really pose a problem considering the expected price tag on the rest of your project. And so long as you can point the Wok-fi in the general direction of the ball, you should be good for real-time data capture.

An even better plan would be to also record the data on the arduino, allowing you to retrieve it later, when the ball is at rest. That way if you miss a bit of the transmission somehow or in case the mini wifi adapter is destroyed in the process, you can still disect the ball and retrieve your data. You'd lose the ball, but without a working wifi adapter it has lost its value already anyways.

Edited by Cooper
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The only reason I was shying away from Bluetooth is because the app creating software that one of my partners knows how to use is not compatible with Bluetooth. I am still thinking that Bluetooth would be the best route to go. As far as charging the device, I am not completely sure how to tackle that. Obviously it would have to be wireless charging so there would have to be a dock of some sort using magnetic resonance.

I have been doing some research on Rf tags. Although they would not be able to necessarily send data, I was wondering if they could have any use in my problem such as being able to measure the doppler effect. Just some ideas.

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Simpsons did it! :p

Sorry, couldn't help myself.

That ball only measures the impulse. This project is to measure velocity and rotation, apparently continuously. Not quite the same.

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