Difference between revisions of "DevGuide/StateInterface"

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The idea is to create a general state interface that holds the most important vehicle states like attitude, position, speed, acceleration.
The general state interface holds all the most important vehicle states like position, velocity, attitude, etc.
It handles coordinate system and fixed-/floating-point conversion on the fly and only when needed.


=== state.h ===
'''See the [http://docs.paparazziuav.org/latest/group__state__interface.html generated documentation] for more details.'''
<pre>
/* Earth Centered Earth Fixed in centimeters */
extern struct EcefCoor_i ecef_pos;


/* lon, lat in radians*1e7  */
The state interface was merged into the master branch with [https://github.com/paparazzi/paparazzi/commit/dbdbbaf6c265c2abeaafcb588e39d2fa6a33536f commit dbdbbaf].
/* alt in centimeters      */
extern struct LlaCoor_i lla_pos;


/* definition of the local (flat earth) coordinate system */
extern struct LtpDef_i ltp_def;
extern bool_t ltp_initialised;


/* North East Down local tangent plane */
[[Category:Software]] [[Category:Developer_Documentation]]
extern struct NedCoor_i ltp_pos;
extern struct NedCoor_i ltp_speed;
extern struct NedCoor_i ltp_accel;
 
/* East North Up local tangent plane */
extern struct EnuCoor_i enu_pos;
extern struct EnuCoor_i enu_speed;
extern struct EnuCoor_i enu_accel;
 
/* vehicle attitude */
extern struct Int32Quat  body_quat;
extern struct Int32Eulers body_euler;
extern struct Int32RMat  body_rmat;
extern struct Int32Rates  body_rate;
 
/* wind and airspeed*/
extern struct Int32Vect3 airspeed;
extern struct Int32Vect3 windspeed;
</pre>
 
Some other possible states:
<pre>
UTM position
Speed norm/dir
Airspeed norm
Heading ?
AGL ?
+ all the previous states available in float
</pre>
 
Everything should be in a "state" structure.
 
=== How to set/get the state ? ===
 
== On time computation ==
 
With this solution, the state can be updated and read with any format with a little overhead (do some tests on a status).
 
The conversion is done only if needed and is not done again until the state is updated.
 
The following structure has to be done for the different "groups" of states: position, speed, attitude,...
 
<pre>
#define XXX 1<<0
#define YYY 1<<1
#define ZZZ 1<<2
uint XYZ_status;
 
// set the new value and reset the status to tell that other format are not up to date anymore
#define STATE_SET_XXX(_v) {
state.XXX = _v;
pos_status = XXX;
}
--> do the same for YYY and ZZZ, and even for XXX_YYY, XXX_ZZZ, ... if needed
 
// get the value and transformation if needed
#define STATE_GET_XXX(_r) {
if (status bit XXX is not set) {
  transform_XXX();
  set bit XXX in status;
}
_r = XXX;
}
--> do the same for the other states
 
// conversion function
// the order the "if _ else if _" is chosen to begin with the less cpu consuming conversions
void transform_XXX() {
if (status bit YYY is set) {
  compute XXX_of_YYY;
} else
if (status bit ZZZ is set) {
  compute XXX_of_ZZZ;
} else
{ // default, no data available
  XXX = ZERO ?
  set UNINIT flag somewhere ?
}
}
--> do the same for the other states
 
--> maybe a part of this could be generated ?
--> we can use functions instead of macros
</pre>

Latest revision as of 07:16, 3 August 2014

The general state interface holds all the most important vehicle states like position, velocity, attitude, etc. It handles coordinate system and fixed-/floating-point conversion on the fly and only when needed.

See the generated documentation for more details.

The state interface was merged into the master branch with commit dbdbbaf.

Retrieved from "http://wiki.paparazziuav.org/w/index.php?title=DevGuide/StateInterface&oldid=18880"