AP_NavEKF: eliminate onGndBaroNoise

libraries/AP_NavEKF/AP_NavEKF.cpp

@@ -406,7 +406,6 @@ NavEKF::NavEKF(const AP_AHRS *ahrs, AP_Baro &baro) :
     flowIntervalMax_ms(100),        // maximum allowable time between flow fusion events
     gndEffectTO_ms(30000),          // time in msec that baro ground effect compensation will timeout after initiation
     gndEffectBaroScaler(4.0f),      // scaler applied to the barometer observation variance when operating in ground effect
-    onGndBaroNoise(0.5f),           // measurement noise used by barometer fusion when on ground
     gndEffectBaroTO_ms(5000)        // time in msec that the baro measurement will be rejected if the gndEffectBaroVarLim has failed it
 
 #if CONFIG_HAL_BOARD == HAL_BOARD_PX4 || CONFIG_HAL_BOARD == HAL_BOARD_VRBRAIN
@@ -1925,12 +1924,10 @@ void NavEKF::FuseVelPosNED()
         R_OBS[3] = sq(constrain_float(_gpsHorizPosNoise, 0.1f, 10.0f)) + sq(posErr);
         R_OBS[4] = R_OBS[3];
         R_OBS[5] = sq(constrain_float(_baroAltNoise, 0.1f, 10.0f));
+
         // reduce weighting (increase observation noise) on baro if we are likely to be in ground effect
-        // when on the ground we use a smaller observation noise because there are less baro disturbances and we can do faster learning of Z accelerometer bias offsets
         if (getGndEffectMode() && vehicleArmed) {
             R_OBS[5] *= gndEffectBaroScaler;
-        } else if (!vehicleArmed) {
-            R_OBS[5] = sq(onGndBaroNoise);
         }
 
         // For data integrity checks we use the same measurement variances as used to calculate the Kalman gains for all measurements except GPS horizontal velocity

libraries/AP_NavEKF/AP_NavEKF.h

@@ -461,7 +461,6 @@ private:
     const float gpsDVelVarAccScale;     // Scale factor applied to vertical velocity measurement variance due to manoeuvre acceleration
     const uint16_t gndEffectTO_ms;      // time in msec that ground effect mode is active after being activated
     const float gndEffectBaroScaler;    // scaler applied to the barometer observation variance when ground effect mode is active
-    const float onGndBaroNoise;         // measurement noise used by barometer fusion when on ground
     const float gndEffectBaroTO_ms;     // time in msec that the baro measurement will be rejected if the gndEffectBaroVarLim has failed it
     const float gpsPosVarAccScale;      // Scale factor applied to horizontal position measurement variance due to manoeuvre acceleration
     const float msecHgtDelay;           // Height measurement delay (msec)