Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: Private Reid on April 09, 2008, 05:31:35 AM

Title: To Buy A Gyro
Post by: Private Reid on April 09, 2008, 05:31:35 AM

Where would I buy a gyro for my robot? And how much would one be?

thanks

Title: Re: To Buy A Gyro
Post by: JesseWelling on April 09, 2008, 06:44:02 AM

Depends on what you need. But I think SparkFun has the best selection.
http://www.sparkfun.com/commerce/categories.php?cPath=23_85

Title: Re: To Buy A Gyro
Post by: Admin on April 14, 2008, 06:51:09 PM

All of the sparkfun gyros that say 'breakout' require an external amplification circuit to get any useful signal out of them:
http://www.societyofrobots.com/schematics_voltamp.shtml


(I bought one and learned the hard way)

Title: Re: To Buy A Gyro
Post by: Private Reid on April 14, 2008, 09:30:37 PM

http://cgi.ebay.com.au/ESKY-RC-plane-model-parts-EK2-0704-Esky-Gyro-for-King-2_W0QQitemZ280217300316QQihZ018QQcategoryZ110026QQssPageNameZWDVWQQrdZ1QQcmdZViewItem (http://cgi.ebay.com.au/ESKY-RC-plane-model-parts-EK2-0704-Esky-Gyro-for-King-2_W0QQitemZ280217300316QQihZ018QQcategoryZ110026QQssPageNameZWDVWQQrdZ1QQcmdZViewItem)

what about this?

this is a gyro

can it be used in a robot?

Title: Re: To Buy A Gyro
Post by: frank26080115 on April 14, 2008, 09:38:28 PM

If I understand correctly, those RC gyros are meant to compensate for torque by helping to adjust the speed of a tail rotor's ESC, which means if you feed it a pulse of 1500 microseconds, it returns a pulse back with a longer or shorter pulse depending on the amount of rotation experienced. So have a microcontroller generate the pulse and read the length of the returned pulse. This is a slower process than analog readings, but hey, it's fast enough for those kickass 3D flying helicopters.

I can be talking out of my ass on this one though, so correct me if I'm wrong.

Title: Re: To Buy A Gyro
Post by: JesseWelling on April 15, 2008, 06:35:41 AM

Quote from: Admin on April 14, 2008, 06:51:09 PM

All of the sparkfun gyros that say 'breakout' require an external amplification circuit to get any useful signal out of them

The Melexis Gyros have SPI output and I can't get at those specific Gyros' DataSheets but at work we use a Melexis Gyro and it's a really good part (we do A2D though), I think we have like a 1 percent degree of error after biasing it.

Title: Re: To Buy A Gyro
Post by: Trumpkin on April 16, 2008, 07:30:01 PM

I think this will work http://www.trossenrobotics.com/store/p/4915-KRG-3-Gyroscopic-Sensor.aspx?feed=Froogle

Title: Re: To Buy A Gyro
Post by: JonHylands on April 17, 2008, 07:28:35 AM

I use this "breakout" gyro board:

http://www.sparkfun.com/commerce/product_info.php?products_id=395

in my six-axis IMU, and I have no trouble hooking the output of that directly to one of the A/D ports on my ATmega168. I get full 0-1023 readings as well.

Admin, why do you think you need an opamp? The part outputs a signal from 0-5 volts...

- Jon

Title: Re: To Buy A Gyro
Post by: Admin on April 20, 2008, 03:41:04 PM

It appears sparkfun has come out with lots of new gyros recently . . . Im not familiar with many of them . . .

This is the one I got:
http://www.sparkfun.com/commerce/product_info.php?products_id=741
It definitely needs amplification . . .