Re: Location Detection

> You just mount an accelerometer on your robot and calibrate it before it
> sets off moving around. The calibration is just setting the starting
> point. Lets suppose that this is A(0,0). When the robot starts to move,
> the accelerometer records the dx, dy and dz of the robot chassis and
> updates the starting point. So after integrating the accelerations you
> get a new point B(x,y).

The IMU's that I've seen are actually comprised of a combination of
gyros and accelerometers.

Gyros measure the rate of change of acceleration, but have a tendency
to drift. Which is why the accelerometers are used - to correct the
error in the gyro.

The problem with use accelerometers by themselves is that you can't
distinguish between tilt and the acceleration of your own robot.

Spark Fun has a whole assortment of accelerometers and gyros
available, already mounted on nice little breakout boards.

http://www.sparkfun.com/shop/index.php?shop=1&cat=71&;

These are the ones I'm currently planning on using:

Freescale just came out with a 3 axis accelerometer in a single chip.
SparkFun has a breakout board for it:
http://www.sparkfun.com/shop/index.php?shop=1&match_criteria=all&rec=&keywords=ACL-MMA7260Q&;

along with 3 of these, all mounted in 3 othogonal planes:
http://www.sparkfun.com/shop/index.php?shop=1&match_criteria=all&rec=&keywords=ACL-ADXRS&;

I have no affiliation with SparkFun - I just like their products.

These guys used to sell kits for building up IMUs:
http://www.rotomotion.com/prd_IMP.html
They have publiished schematics and stuff. I believe that some of the
components they used are obsolete now, and this is partly what
prompted SparkFun to make some of their offerings.

-- 
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/


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