To get my quadrocopter stabelized I use the Razor 9 Degrees of Freedom inertial measurement unit. This 9DOF IMU is AHRS (Attitude and heading reference system) compatible. More info about this imu: Razor 9DOF
My first test with this board learned me that the data from the original firmeware is very sensitive for external noise.
A quadrocopter has 4 motors. And that is a lot of vibrations. The original firmeware for this board sends raw data comming from the sensors. When my motors are on > 60% power, this raw data can't be used and the need for a good software filter (algoritme) is essential.
The new AHRS firmeware for this board uses the DCM (Direction Cosine Matrix) algoritme. This should reduce error (noise) in data and eliminate drift. Test result for new firmeware will be posted in next blog. The AHRS firmeware can be downloaded here: Razor 9DOF IMU AHRS code