GPS + Accelerometer + Kalman Filter --> radio controlled aircraft pose

I want to build a pose (position and attitude) measurement/estimation unit for my radio controlled aircraft by using * A PIC or an AVR microcontroller or an Ipaq PDA
* A GPS receiver with serial data output * 3 x ADXL ??? accelerometer (3 axis, X,Y,Z) * Kalman filter * Expert advice from robotics gurus on the news group
- Reading the GPS data from the seial port is not difficult - Digitizing ADXL ??? accelerometer outputs from 3 sensor is not difficult either - Using Kalman Filter to fuse GPS and ADXL outputs is NOT easy for me. (I'm trying to learn Kalman Filter) - Can some one help me how to combine/fuse four input data; (GPS + accelerations on X,Y,Z axis) to estimate accuratelly the pose of the aircraft ?
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Here's a site with some info and links to tutorials. I'd like to learn how to apply them as well for the same application.
http://www.cs.unc.edu/~welch/kalman /
--
Shawn

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goyiarteva wrote:

See: http://rotomotion.com/index.html and http://autopilot.sourceforge.net /
Mitch
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difficult
(I'm
You can get aircraft position with all that but you're going to need sensors detecting the rotations in each axis to get pitch/roll/yaw attitude. Think solid state gyros.
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do you think 3 accelerometers are not enough for that?

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goyiarteva wrote:

need
attitude.
Actually, I don't think he'd be able to get a good estimation of attitude based on those sensors. Position (alt, latitude, long) sure... but for attitude you'd need either low-drift gyros, a horizon sensor, or something similar.
Dave
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You need to detect the rotation of the vehicle to get attitude. Accels detect the translation of the vehicle.
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Steve wrote:

Accels
Yeah, or use a reference (or multiple references), like a magnetometer, a horizon sensor, or a sun sensor.
Dave
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goyiarteva wrote:

No. Visit that Rotomotion link Mitch posted. You need to measure linear *and* rotationally acceleration in 3D space.
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You can get attitude from gyros alone, although not full position. Regardless, (without a big budget) I don't think you'd be able to get prolonged, accurate attitude information unless you had a really fast processor and very low-drift gyros.
Dave
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