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Advice needed selecting sensor for quadcopter — Parallax Forums

Advice needed selecting sensor for quadcopter

doggiedocdoggiedoc Posts: 2,245
edited 2011-05-07 05:39 in General Discussion
Hi all. I am looking for advice on selection of an accelerometer and gyroscope for a quadcopter project I am starting. I'll be using a propeller as MCU-- likely the Gadget Gangster Propeller Platform as I have 3 or 4 of them.

I am considering the module for GG: http://www.gadgetgangster.com/find-a-project/56?projectnum=367 ... but haven't quite visualized the interface yet.


Otherwise I am considering the hitachi from Parallax: http://www.parallax.com/Store/Sensors/AccelerationTilt/tabid/172/CategoryID/47/List/0/SortField/0/Level/a/ProductID/97/Default.aspx
...combined with gyroscope also from Parallax: http://www.parallax.com/Store/Sensors/AccelerationTilt/tabid/172/CategoryID/47/List/0/SortField/0/Level/a/ProductID/588/Default.aspx

I am open to suggestions and pointers from anyone that may have traveled down this path before me!

Thanks in advance,
Paul

Comments

  • JasonDorieJasonDorie Posts: 1,930
    edited 2011-05-03 16:40
    Mine uses these:

    ITG-3200 : http://www.sparkfun.com/products/9801
    ADXL345 : http://www.sparkfun.com/products/9836

    Both use I2C interfaces, and therefore don't require an external ADC. The ITG has user-settable sample and filtering rates, and has a 16-bit on-board ADC. The accelerometer is 1G=8 bit, giving 13 bit precision total over the whole range.

    The two together are about the same price as the Gadget Gangster module. I have a combined driver for the two chips that uses PASM in one cog to communicate with both at 200Hz (though it will support much higher rates).

    The gyro also has a temperature sensor on board which can be used for drift compensation. (My code does this too, though it's set specifically for my gyro).

    This vid is my quad using ONLY the gyro (no accelerometer at all): http://www.youtube.com/watch?v=EjvJLm725h0
    Toward the end I take my hands off the controller for about 10 seconds to show how stable it is.

    And this is the same board using both, though I haven't gotten anything flying with it yet: http://www.youtube.com/watch?v=4bj2ieD4HA0
  • Roy ElthamRoy Eltham Posts: 3,000
    edited 2011-05-03 17:37
    I recently got one of these boards: http://www.sparkfun.com/products/10252 It's similar to what JasonDorie is using, it's just a little more "stuff going on" in the IMU3000 (which is a IGT3200 with some more stuff in it to directly interface with attach accelerometer and do some of the fusing work for you).

    I've been reading that people have had some issues getting the "extra" fusing feature to work properly, but you can just read the gyro and accelerometer raw data, and so it's like having the two separate boards in one. I plan to make an attempt at some point to get the DMP (that extra fusing thing) working...but Probably not in the short term...

    Roy
  • Cluso99Cluso99 Posts: 18,069
    edited 2011-05-05 02:08
    Another cheap gyro is the wii motion plus (~$10 on eBay) and accel is in the wii nunchuck (IIRC ~$5). I also have the ICs but this seems a cheaper way in to this.
  • doggiedocdoggiedoc Posts: 2,245
    edited 2011-05-05 17:39
    Thank you all for the links and suggestions! I had hoped to have more time this week for ordering parts, but perhaps this weekend will be better.

    @Cluso99 - I had forgotten about the Wii controllers! I'm sure my kids wouldn't miss one or two!! LOL
  • Cluso99Cluso99 Posts: 18,069
    edited 2011-05-06 01:50
    doggiedoc: Its the wii motion plus.. the little box that plugs into the end of the wii controller has the gyros. The pcb is about 1/2-3/4" square with 4 pins of I2C (5V, SDA, SCL and GND - not sure of the sequence). The nunchuck pcb is a little larger, and again I2C.
  • max72max72 Posts: 1,155
    edited 2011-05-06 04:44
    true.. the boards are very small.
    Moreover the Nunchuk hosts also the button+joystick interface. I was able to cut the board in half, leaving only the accelerometers, reducing the size.
    In my case there were two "dents" on the PCB suggesting a cutting line...
    Massimo
  • doggiedocdoggiedoc Posts: 2,245
    edited 2011-05-06 10:22
    Cluso99 wrote: »
    doggiedoc: Its the wii motion plus.. the little box that plugs into the end of the wii controller has the gyros. The pcb is about 1/2-3/4" square with 4 pins of I2C (5V, SDA, SCL and GND - not sure of the sequence). The nunchuck pcb is a little larger, and again I2C.

    Cool, I have those too! I'm going to take one apart this weekend. Time to learn I2C!!
  • Roy ElthamRoy Eltham Posts: 3,000
    edited 2011-05-06 13:27
    The March 2011 Nuts & Volts has an article by Jon Williams (Spin Zone) about interfacing with the Wii nunchuk via I2C. It includes how to wire it up and some code for interfacing with it. That would be a good place to start with using the Motion Plus thing.

    This website has all the information you need for talking with the Motion Plus (along with any other of the extension controllers for the Wii): http://wiibrew.org/wiki/Wiimote/Extension_Controllers It details the data format of the I2C bytes you read back from it.

    Roy
  • Al BoothAl Booth Posts: 137
    edited 2011-05-06 16:04
    You might want to look at these. Atmel has a new line of boards for their AVR's and have started some sensor boards. Two of the boards at this link are 9 axis (3 accelerometer, 3 gyro, and 3 compass) and sell for $54.

    http://www.atmel.com/products/AVR/sensors_xplained.asp
  • doggiedocdoggiedoc Posts: 2,245
    edited 2011-05-07 05:39
    @Roy Eltham, thanks for that info and link. I've always liked Jon's articles. I've let my N&V subscription lapse. Time to renew!!

    Paul
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