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

[Andrew S]

Hi Felix,
Where is the paparazzi KF?
Andrew


13.04.10, 08:35, "Felix Ruess" <address@hidden>:

> Hi Andrew,
>  
>  Whether you represent your angles in a way that they have
>  singularities (like euler angles) or not (like quaternions or dcm) has
>  nothing to do with the choice of your estimator (e.g. EKF or
>  complementary filter or your PI controller). In any case you have to
>  transform your IMU measurements from the IMU frame into the navigation
>  frame (assumed to be the same as the inertial frame considering the
>  quality of the sensors).
>  The paparazzi KF uses quaternions as angle representations (you really
>  don't want to use dcm here) but also converts the latest quaternion
>  attitude estimate to euler angle and dcm representations for ease of
>  use.
>  
>  Cheers, Felix
>  
>  2010/4/6 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" :
>  >
>  >> 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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>  >>
>  >>
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