AP_NavEKF: Default parameter adjustments

Bring Plane glitch protection thresholds into alignment with copter and
rover
Slight increase in accelerometer bias process noise to prevent bias
estimate divergence into limits (Rover and Plane only as Copter does not
seem respond as well to this change)
effective increase in threshold on divergence test to allow increased
margin for bad GPS velocities

libraries/AP_NavEKF/AP_NavEKF.cpp

@@ -56,7 +56,7 @@
 #define GYRO_PNOISE_DEFAULT     0.015f
 #define ACC_PNOISE_DEFAULT      0.25f
 #define GBIAS_PNOISE_DEFAULT    1E-06f
-#define ABIAS_PNOISE_DEFAULT    0.0001f
+#define ABIAS_PNOISE_DEFAULT    0.0002f
 #define MAGE_PNOISE_DEFAULT     0.0003f
 #define MAGB_PNOISE_DEFAULT     0.0003f
 #define VEL_GATE_DEFAULT        2
@@ -77,16 +77,16 @@
 #define GYRO_PNOISE_DEFAULT     0.015f
 #define ACC_PNOISE_DEFAULT      0.25f
 #define GBIAS_PNOISE_DEFAULT    1E-06f
-#define ABIAS_PNOISE_DEFAULT    0.0001f
+#define ABIAS_PNOISE_DEFAULT    0.0002f
 #define MAGE_PNOISE_DEFAULT     0.0003f
 #define MAGB_PNOISE_DEFAULT     0.0003f
-#define VEL_GATE_DEFAULT        3
+#define VEL_GATE_DEFAULT        2
 #define POS_GATE_DEFAULT        10
 #define HGT_GATE_DEFAULT        10
 #define MAG_GATE_DEFAULT        3
 #define MAG_CAL_DEFAULT         0
 #define GLITCH_ACCEL_DEFAULT    150
-#define GLITCH_RADIUS_DEFAULT   50
+#define GLITCH_RADIUS_DEFAULT   15
 
 #endif // APM_BUILD_DIRECTORY
 
@@ -3400,7 +3400,7 @@ void NavEKF::checkDivergence()
     float tempLength = tempVec.length();
     if (tempLength != 0.0f) {
         float temp = constrain_float((P[10][10] + P[11][11] + P[12][12]),1e-12f,1e-8f);
-        scaledDeltaGyrBiasLgth = (2e-6f / temp) * tempVec.length() / dtIMU;
+        scaledDeltaGyrBiasLgth = (1e-6f / temp) * tempVec.length() / dtIMU;
     }
     bool divergenceDetected = (scaledDeltaGyrBiasLgth > 1.0f);
     lastGyroBias = state.gyro_bias;