From aed6c791351a4fa1e39a1976e64b153339634027 Mon Sep 17 00:00:00 2001
From: Paul Riseborough <p_riseborough@live.com.au>
Date: Tue, 31 Dec 2013 17:06:56 +1100
Subject: [PATCH] AP_NavEKF: Added gyro bias variance scale for on-ground

---
 libraries/AP_NavEKF/AP_NavEKF.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libraries/AP_NavEKF/AP_NavEKF.cpp b/libraries/AP_NavEKF/AP_NavEKF.cpp
index 2abdbee6f9..899df9df1f 100644
--- a/libraries/AP_NavEKF/AP_NavEKF.cpp
+++ b/libraries/AP_NavEKF/AP_NavEKF.cpp
@@ -374,6 +374,7 @@ void NavEKF::CovariancePrediction()
 
     for (uint8_t i= 0; i<=9;  i++) processNoise[i] = 1.0e-9f;
     for (uint8_t i=10; i<=12; i++) processNoise[i] = dAngBiasSigma;
+    if (onGround) processNoise[12] = dAngBiasSigma * yawVarScale;
     for (uint8_t i=13; i<=15; i++) processNoise[i] = dVelBiasSigma;
     for (uint8_t i=16; i<=17; i++) processNoise[i] = windVelSigma;
     for (uint8_t i=18; i<=20; i++) processNoise[i] = magEarthSigma;