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Calling All Accelerometer Gurus

NEED HELP1

My ultimate goal is to have an accelerometer and a microprocessor work in combination to accomplishing the following:

Hypothetically: Say I have a rubber ball that contained a two or three axis accelerometer & microprocessor and allowed it to roll down a slight incline. The incline is so shallow that it would only roll approximately 5ft. before it came to a complete stop. The rolling surface would be an asphalt pavement, like that of a street witch would allow some deviation in one roll compared to the next. I would then use the information from the accelerometer as the standard and compare it to any number of rolls then after. Each roll would be under the same conditions. Then set an adjustable tolerance of the deviation from one roll to the next compared to the standard. An alarm would go off if the roll was not within the allowable tolerance.

I have very limited experience in this field. I am familiar with basic electronic circuits and components.

Say it was possible to place a LCD on the ball could it display the following:

  1. A plot in-which one roll vs. the other?
  2. A plot in-which each roll against each multiple Plots such as g force / time, speed / time, g force / distance, x / y axis?

Other Questions

  1. Could I download the information to a lap top and plot it from there?
  2. Could I have multiple sounds or colored LEDs that would designate in which part of the roll (distance) it went out of tolerance?

  1. Is there a package out there for purchase that would comprise of an accelerometer, microprocessor and standard code that records the speed, distance, g. force, position ect. of an object in motion? This would allow me to tweak the code.

  2. If not what would be the closest electronic device that would do something similar, besides the individual components that would need to be assembled together by myself?

  1. Are there people out there that would put this together for a fee.

Any information at all on this subject would greatly be appreciated. I've been to most of the sites on the web and read as much as I could.

DaveK

Reply to
DaveK
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Measurement Computing (and other companies... search for data aquisition and analog inputs) has a wireless accelerometer you could embed in a ball of some size or another and a graphing package to view the data.

Reply to
BobG

Try this wireless Bluetooth accelerometer:

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Dave.

Reply to
David L. Jones

Re.3. All those are integrals of acceleration against time. Any guided and unguided rocket should have the relevant software included in its computer. Try NASA or similar.

Good luck

Stanislaw.

Reply to
Stanislaw Flatto

Putting accelerometers in a rolling ball is going to make for a really messy computation, what with all the axes rolling in arbitrary directions. Is this really needed?

You seem to have decided upon a solution and are asking for help in implementing it. Instead, perhaps if you defined the actual problem you want to solve, we could propose better approaches.

Best regards,

Bob Masta D A Q A R T A Data AcQuisition And Real-Time Analysis

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Scope, Spectrum, Spectrogram, Signal Generator Science with your sound card!

Reply to
Bob Masta

Yes, but it would have to be a large ball.

Yes. This would allow you to dispense with the LCD, and make the ball smaller. With a bit more development time you could make an inductive coupler that would talk to the PC wirelessly and charge the sensor board's batteries. With luck, this would let you seal the ball.

Yes, although getting sounds out of the ball without weakening it may be a challenge.

Not for what you want, I think. Check Spark Fun for the bits, though.

An IMU would do the measurements, although I think that for what you need an 'ordinary' IMU is 100 to 1000 times more expensive than could be achieved by building something up from components.

The 'easy' algorithms to allow you to record distance & speed require that you supply three axes worth of rotational information, and gyros are more expensive than accelerometers. I think that if you can trust the ball to grip the surface you could use just accelerometer input -- you'd have to do some analysis to verify that theory, though.

I certainly could, and have fun doing it, too. Contact me via email (tim at wescottdesign dot com).

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
Reply to
Tim Wescott

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