AP_AHRS: cope with the changed semantics of airspeed.use()

libraries/AP_AHRS/AP_AHRS.cpp

@@ -126,7 +126,7 @@ const AP_Param::GroupInfo AP_AHRS::var_info[] PROGMEM = {
 // return airspeed estimate if available
 bool AP_AHRS::airspeed_estimate(float *airspeed_ret) const
 {
-	if (_airspeed && _airspeed->use()) {
+	if (airspeed_sensor_enabled()) {
 		*airspeed_ret = _airspeed->get_airspeed();
 		if (_wind_max > 0 && _gps.status() >= AP_GPS::GPS_OK_FIX_2D) {
                     // constrain the airspeed by the ground speed

libraries/AP_AHRS/AP_AHRS.h

@@ -260,7 +260,7 @@ public:
     // return true if airspeed comes from an airspeed sensor, as
     // opposed to an IMU estimate
     bool airspeed_sensor_enabled(void) const {
-        return _airspeed != NULL && _airspeed->use();
+        return _airspeed != NULL && _airspeed->use() && _airspeed->healthy();
     }
 
     // return a ground vector estimate in meters/second, in North/East order

libraries/AP_AHRS/AP_AHRS_DCM.cpp

@@ -559,7 +559,7 @@ AP_AHRS_DCM::drift_correction(float deltat)
             return;
         }
         float airspeed;
-        if (_airspeed && _airspeed->use()) {
+        if (airspeed_sensor_enabled()) {
             airspeed = _airspeed->get_airspeed();
         } else {
             airspeed = _last_airspeed;
@@ -850,7 +850,7 @@ void AP_AHRS_DCM::estimate_wind(void)
         }
 
         _last_wind_time = now;
-    } else if (now - _last_wind_time > 2000 && _airspeed && _airspeed->use()) {
+    } else if (now - _last_wind_time > 2000 && airspeed_sensor_enabled()) {
         // when flying straight use airspeed to get wind estimate if available
         Vector3f airspeed = _dcm_matrix.colx() * _airspeed->get_airspeed();
         Vector3f wind = velocity - (airspeed * get_EAS2TAS());
@@ -923,7 +923,7 @@ bool AP_AHRS_DCM::get_position(struct Location &loc) const
 bool AP_AHRS_DCM::airspeed_estimate(float *airspeed_ret) const
 {
 	bool ret = false;
-	if (_airspeed && _airspeed->use()) {
+	if (airspeed_sensor_enabled()) {
 		*airspeed_ret = _airspeed->get_airspeed();
 		return true;
 	}