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AP_Airspeed: added ARSPD_TUBE_ORDER parameter 

This allows for either order of tube connection by default, but the
order can be specified if need be
This commit is contained in:
Andrew Tridgell 2014-02-14 22:07:12 +11:00
parent 2bf7a46c9b
commit d853d65b84
2 changed files with 30 additions and 10 deletions
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36
libraries/AP_Airspeed/AP_Airspeed.cpp
View File

@ -93,6 +93,12 @@ const AP_Param::GroupInfo AP_Airspeed::var_info[] PROGMEM = {
// @User: Advanced
AP_GROUPINFO("AUTOCAL", 5, AP_Airspeed, _autocal, 0),
// @Param: TUBE_ORDER
// @DisplayName: Control pitot tube order
// @Description: This parameter allows you to control whether the order in which the tubes are attached to your pitot tube matters. If you set this to 0 then the top connector on the sensor needs to be the dynamic pressure. If set to 1 then the bottom connector needs to be the dynamic pressure. If set to 2 (the default) then the airspeed driver will accept either order. The reason you may wish to specify the order is it will allow your airspeed sensor to detect if the aircraft it receiving excessive pressure on the static port, which would otherwise be seen as a positive airspeed.
// @User: Advanced
AP_GROUPINFO("TUBE_ORDER", 6, AP_Airspeed, _tube_order, 2),
AP_GROUPEND
};
@ -180,17 +186,27 @@ void AP_Airspeed::read(void)
if (!_enable) {
return;
}
/*
when we get negative pressures it means the tubes are probably
connected the wrong way around. We don't just use the absolute
value as otherwise we could get bad readings in some flight
attitudes (eg. a spin) due to pressure on the static port
*/
airspeed_pressure = get_pressure() - _offset;
if (airspeed_pressure < -32) {
// we're reading more than about -8m/s. The user probably has
// the ports the wrong way around
_healthy = false;
/*
we support different pitot tube setups so used can choose if
they want to be able to detect pressure on the static port
*/
switch ((enum pitot_tube_order)_tube_order.get()) {
case PITOT_TUBE_ORDER_NEGATIVE:
airspeed_pressure = -airspeed_pressure;
// fall thru
case PITOT_TUBE_ORDER_POSITIVE:
if (airspeed_pressure < -32) {
// we're reading more than about -8m/s. The user probably has
// the ports the wrong way around
_healthy = false;
}
break;
case PITOT_TUBE_ORDER_AUTO:
default:
airspeed_pressure = fabsf(airspeed_pressure);
break;
}
airspeed_pressure = max(airspeed_pressure, 0);
_last_pressure = airspeed_pressure;

4
libraries/AP_Airspeed/AP_Airspeed.h
View File

@ -133,6 +133,9 @@ public:
static const struct AP_Param::GroupInfo var_info[];
enum pitot_tube_order { PITOT_TUBE_ORDER_POSITIVE =0,
PITOT_TUBE_ORDER_NEGATIVE =1,
PITOT_TUBE_ORDER_AUTO =2};
private:
AP_Float _offset;
@ -141,6 +144,7 @@ private:
AP_Int8 _enable;
AP_Int8 _pin;
AP_Int8 _autocal;
AP_Int8 _tube_order;
float _raw_airspeed;
float _airspeed;
float _last_pressure;