msg: Add topic for pre-flight sensor checks

msg/CMakeLists.txt

@@ -91,6 +91,7 @@ set(msg_file_names
 	sensor_combined.msg
 	sensor_gyro.msg
 	sensor_mag.msg
+	sensor_preflight.msg
 	servorail_status.msg
 	subsystem_info.msg
 	system_power.msg

msg/sensor_combined.msg

@@ -22,4 +22,3 @@ float32[3] magnetometer_ga		# Magnetic field in NED body frame, in Gauss
 int32 baro_timestamp_relative		# timestamp + baro_timestamp_relative = Barometer timestamp
 float32 baro_alt_meter			# Altitude, already temp. comp.
 float32 baro_temp_celcius		# Temperature in degrees celsius
-

msg/sensor_preflight.msg

@@ -0,0 +1,6 @@
+#
+# Pre-flight sensor check metrics. These will be zero if the vehicle only has one sensor.
+# The topic will not be updated when the vehicle is armed
+#
+float32 accel_inconsistency_m_s_s  # magnitude of maximum acceleration difference between IMU instances in (m/s/s).
+float32 gyro_inconsistency_rad_s   # magnitude of maximum angular rate difference between IMU instances in (rad/s).