[Paparazzi-devel] New State Interface in master branch

[Gautier Hattenberger]

Hi everyone,

The master branch is now using a general state interface common to all 
firmwares 
(https://github.com/paparazzi/paparazzi/commit/dbdbbaf6c265c2abeaafcb588e39d2fa6a33536f).

This interface holds the most important vehicle states like attitude, 
position, speed, acceleration in different representations (eulers, 
quaternion, utm, lla, ltp, ...). The estimation filters (AHRS, INS, ...) 
can directly feed this central interface each with their own format. A 
key feature of this system is that you don't access the variables 
directly anymore, but use inline function to get (and set) the state and 
an automatic conversion is perform when needed.

When you e.g. set the position in ECEF coordinates, you only set the 
status bit for that position representation (clearing all others). If 
you then want to get the position in local NED coordinates this 
representation is computed on-the-fly and the status bit for that 
representation set. If you get the same representation again before a 
new position has been set, the representation won't be recomputed 
because it is already up-to-date (status bit for that position 
representation is one).

The files holding this interface are sw/airborne/state.c and .h

Most of the possible internal conversions are already implemented and 
are sufficient to cover the current state of the airborne code.
Moreover, all the firmwares/subsystems/modules in the master should now 
be converted to this new state interface.
Please use this interface for your futur developments and don't hesitate 
to report bugs. It is recommanded to make careful pre-flight checks and 
to do simulations before flying.

The known bugs are some debug messages that might send 0.

This new feature closes 
https://github.com/paparazzi/paparazzi/issues/101 and 
https://github.com/paparazzi/paparazzi/pull/237

A wiki page was started a long time ago and is a bit out-dated but gives 
the general idea of the interface 
(http://paparazzi.enac.fr/wiki/DevGuide/StateInterface). The doxygen 
docs will be automatically generated very soon.


Cheers,

Gautier (and Felix)