Re: [Paparazzi-devel] Paparazzi EKF- and compelmentary- filter

[Andrew S]

Hi
For my view, EKF is unnecessary as it loads microcontroller. You can use even 
simple PI controller. It works worse than EKF, but quite well. For good results 
PI regulator should be adjusted for 10 seconds of correction after 180 degrees 
error. Also I can say cheap two axis gyros by ST are unusable because of cross 
axis interference and whey do not have tolerancy against vibration. 
Complementary one axis Z-gyros are better.
For correct angles EKF is not a solution, you need for example Directional 
cosine matrices for calculations between body and earth frames. The problem is 
that gyros works in the body frame, but accelerometers works in the earth 
frame. In fact when pitch is near 90 degrees, the roll gyro indicates jaw :)  
EKF will not helps for this.
Andrew

02.04.10, 17:41, "Prof. Dr.-Ing. Heinrich Warmers" <address@hidden>:

> Hello,
>  we made same experiments with a EKF based  on the rotomotion solution in 
>  combination with the tiny13 and a low cost analogue IMU from sparkefun.
>  By the test i saw that the software is not  possible to  deal with  
>  pitch  angeles over  90°. So  to fly a looping is impossible.
>  If  90° arrives it is  impossible to get the correct angeles by the g 
>  force since static  z acceleration is zero.
>  If the pitch angels is more than  120°  the roll angeles rotate fast. 
>  What is about the  paparazzi  booz ekf and complementary filter. Can 
>  they deal  all angeles ? 
>  In the video from 2006  i saw only small  angeles.
>  
>  Cheers
>  
>  Heinrich
>  
>  
>  
>  
>  
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