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sanddrag
12-15-2003, 08:34 PM
I need a good cheap gyro/accelerometer/tilt sensor/ whatever you call it for my balancing vehicle project. It needs to be easily compatible with a BS2. I was thinking of using this one (or maybe two) Parallax sells http://www.parallax.com/detail.asp?product_id=28017 Will this work? How do I know what would be a good one or not? Thanks.

sanddrag
12-16-2003, 09:56 PM
Anyone? I need to order this really soon. Thanks.

Joe Johnson
12-17-2003, 01:22 PM
You can get the yaw rate sensors from Future that were discussed by Chris Hibner.
See this thread (http://www.chiefdelphi.com/forums/showthread.php?t=22582)

From that thread: There are two models, the ADXRS150 and the ADXRS300. The number corresponds to the max degrees per second. There is an evaluation board available at Future and Arrow that includes all the caps in the sample application in the datasheets. The part number has an -EB appended to it. Those devices are about the size of a pencil eraser and are a ball-grid array so you can't solder them by hand. The EB parts look like a basic stamp and can be pushed into a regular 20 pin IC socket.



They are not exactly cheap. The ADXRS150EB (the one in a DIP package rather than the ball grid array, which is hard/impossible to deal with for most people) is $94 from Future Electronics (http://www.futureelectronics.com/). I have a recollection of a price of $75 or so from NewarkInOne.com, but when I went there to find it, I struck out.

As to compatible with the Stamp2, you are more or less on your own. I feel pretty sure that you will struggle to do the calculations you are likely to have to do without a faster CPU, but don't let me stop you.

Good luck.

Joe J.

P.S. You could always ask around on Chief Delphi for old FIRST gyros. Many teams never touch them. You may be able to find a bargain. JJ

Rickertsen2
12-17-2003, 04:06 PM
I have the acecelerometer you mentioned above. It works, but its a pain. I would recommend the ADXRS150 and the ADXRS300 gyros mentioned above. If you don't need much prescision, but need accuracy over time then i would point you to: http://www.acroname.com/robotics/parts/R117-COMPASS.html

sanddrag
12-17-2003, 06:23 PM
Will the Memsic one Parallax sells work for a balancing vehicle application? It seems like it would be the easiest to use with the BS2 and also the cheapest. The ADXRS300 and ADXRS150 I can get for about $55 but I don't know how to use them with the BS2. The Memsic has sample code but I don't know if it will work. Does anyone else know?

seanwitte
12-19-2003, 07:31 AM
Will the Memsic one Parallax sells work for a balancing vehicle application? It seems like it would be the easiest to use with the BS2 and also the cheapest. The ADXRS300 and ADXRS150 I can get for about $55 but I don't know how to use them with the BS2. The Memsic has sample code but I don't know if it will work. Does anyone else know?

I know its not the same as using inertial parts, but there is a lego mindstorms project called the Legway that uses infrared proximity sensors to balance vertically. You can get the sensors from Acroname for $11.50. The GDPD12 would work fine as long as you keep it 4" away from the floor. You'll need to get an ADC, but Parallax has one with sample code that is very easy to use.

Al Skierkiewicz
12-19-2003, 09:33 AM
Will the Memsic one Parallax sells work for a balancing vehicle application?
In looking at the specs, that device is only able to resolve 2G max and that may not be enough for your application. This is where experimentation is going to be a factor. If time is of the essence, than cost can't be. (In other words there is not enough data to make a recomendation at this point. If you need it now, get something that has wider specs than you think you need. If you don't, you will be waiting around for a better one to ship after you have determined the first one doesn't work.)
Sorry, Sanddrag.