use LPE estimator

ROMFS/px4fmu_common/init.d/rc.balloon_apps

@@ -8,4 +8,35 @@
 #
 # Start the attitude and position estimator.
 #
-ekf2 start &
+
+if param compare SYS_MC_EST_GROUP 1
+then
+	#
+	# Try to start LPE. If it fails, start EKF2 as a default.
+	# Unfortunately we do not build it on px4_fmu-v2 due to a limited flash.
+	#
+	if attitude_estimator_q start
+	then
+		echo "WARN [init] Estimator LPE unsupported, EKF2 recommended."
+		local_position_estimator start
+	else
+		echo "ERROR [init] Estimator LPE not available. Using EKF2"
+		param set SYS_MC_EST_GROUP 2
+		param save
+		reboot
+	fi
+else
+	#
+	# Q estimator (attitude estimation only)
+	#
+	if param compare SYS_MC_EST_GROUP 3
+	then
+		attitude_estimator_q start
+	else
+		#
+		# EKF2
+		#
+		param set SYS_MC_EST_GROUP 2
+		ekf2 start &
+	fi
+fi

ROMFS/px4fmu_common/init.d/rc.balloon_defaults

@@ -16,4 +16,5 @@ then
 	# FW takeoff acceleration can easily exceed ublox GPS 2G default.
 	#
 	param set GPS_UBX_DYNMODEL 8
+  param set SYS_MC_EST_GROUP 1
 fi