LPE : add support for precision landing measurement fusion

src/modules/local_position_estimator/params.c

@@ -424,6 +424,17 @@ PARAM_DEFINE_FLOAT(LPE_LAND_Z, 0.03f);
  */
 PARAM_DEFINE_FLOAT(LPE_LAND_VXY, 0.05f);
 
+/**
+ * Minimum landing target standard covariance, uses reported covariance if greater.
+ *
+ * @group Local Position Estimator
+ * @unit m^2
+ * @min 0.0
+ * @max 10
+ * @decimal 2
+ */
+PARAM_DEFINE_FLOAT(LPE_LT_COV, 0.0001f);
+
 /**
  * Integer bitmask controlling data fusion
  *