1 CanberraUAV Workshop Ground Control StationsFeb 2017

2 Ground Control StationsAlso known as GCS Communicate with the UAV Receive telemetry data Send commands to UAV

3 GCS -Introduction Telemetry Data Data sent from UAV to GCSContains information about the current state of the UAV Speed Position Altitude System errors

4 GCS -Introduction Command data Data sent from GCS to UAV Can beFlight commands (RTL, Goto waypoint) Get/set flight parameters Get/set mission waypoints

5 GCS -Introduction A GCS Consists of Communications Link GCS ComputerGCS Software Other accessories - live video feed, tracking antenna, DGPS base station, etc as required

6 GCS - Software Options Most GCS software is run on laptopsDifferent options depending on Which flight controller is used GCS Operating System Require features Open source and commercial offerings

7 GCS - Software Options Software Runs on Linux Runs on WindowsRuns on OSX Mission Planner YY Y MAVProxy APM Planner 2 Qground control UgCS

8 GCS - Software Options Software Runs on Android Runs on iOS Tower YYMAVPilot SidePilot AndroPilot

9 GCS - Software Options Compatibility and features vary widely between GCS programs

10 GCS - MAVLink Micro Air Vehicle LinkStandardised protocol for most open-source flight controllers Though some flight controllers may have extra MAVLink messages Efficient and low datarate Includes CRC to ensure validity of data 3 versions - 0.9, 1.0, 2.0 Arduplane can use 1.0 or 2.0 (default 1.0)

11 GCS - MAVLink Byte Index Content Value Explanation Packet start signPacket start sign v1.0: 0xFE (v0.9: 0x55) Indicates the start of a new packet. 1 Payload length Indicates length of the following payload. 2 Packet sequence Each component counts up his send sequence. Allows to detect packet loss 3 System ID ID of the SENDING system. 4 Component ID ID of the SENDING component. 5 Message ID ID of the message - the id defines what the payload “means” and how it should be correctly decoded. 6 to (n+6) Data ( ) bytes Data of the message, depends on the message id. (n+7) to (n+8) Checksum (low byte, high byte) ITU X.25/SAE AS-4 hash, excluding packet start sign, so bytes 1..(n+6)

12 GCS - MAVLink

13 GCS - MAVLink

14 GCS - MAVLink There are MAVLink messages for sending/receiving parameters and missions Typically, a flight controller may only send some of the messages - depending on it’s features, settings and current state

15 GCS - MAVLink MAVLink does include any encryptionUp to the user to implement in their communications link MAVLink 2.0 includes a “signing key” 32-bit number Flight controller will only accept commands from packet signed with this key Disabled by default

16 GCS - Flight Planning Creating the waypoints to achieve the mission objectives

17 GCS - Flight Planning What is the mission objective?Primary and secondary goals Payload required UAV required Most GCS software packages have a mission planning screen where you can drag-n-drop waypoints

18 GCS - Flight Planning Considerations Takeoff/landing areaHills/Terrain Flight altitude Mission length (km) Weather (wind) Communications coverage

19 GCS - Flight Planning If possible, run the mission in SITL beforehand, to ensure the waypoints are correctly laid out Some GCS software packages have auto- generation of waypoints for mowing-the- lawn surveys

20 Practical Session 1 (20min)Create a mission that: Perform an aerial survey of the Snowy Hydro base Considerations: Takeoff/landing at CMAC Landing will be manual Create the mission, run in SITL cd ./ArduPlane ../Tools/autotest/sim_vehicle.py Two options for GCS tool to use for mission planning (choose one) Connect Mission Planner via UDP, port 14550 Use module load misseditor in MAVProxy

21 GCS - Advanced PlanningGeofences A single closed polygon UAV will turn back if it crosses outside of the polygon Note that the UAV’s inertia may send it beyond the fence for a short period

22 GCS - Advanced PlanningRally points Instead of a single Home point, have a set of rally points On RTL, the UAV will head to the nearest rally point

23 GCS - Advanced PlanningTerrain Following Terrain data stored on Pixhawk’s SD card Arduplane will look at this database to estimate it’s AGL Available in AUTO, RTL and other flight modes. Will maintain a constant height above ground Set TERRAIN_ENABLE to 1 and TERRAIN_FOLLOW to 1 Note the datasource is the SRTM data, so is only accurate to 20m

24 GCS - Post flight analysisTwo types of logfiles GCS - saved copy of MAVlink stream (tlog) APM - saved on SD card (bin) Bin log has more messages at a faster rate Generally the preferred log when analysing a flight Tlog is on the GCS, so can be used if the UAV goes missing or is destroyed Still worth searching the crash site for the SD card!

25 GCS - Post flight analysisTlogs are stored in: Mission Planner C:\Program Files (x86)\Mission Planner\logs MAVProxy Same folder that MAVproxy was run from (unless using the --aircraft option)

26 GCS - Post flight analysisMost flight analysis tools will work with both bin files and tlog files Popular Flight Analysis tools: Mission Planner MAVExplorer (part of MAVProxy)

27 GCS - Post flight analysis

28 GCS - Post flight analysisMechanical Failures These appear in the log as a sudden divergence in the desired roll and pitch vs the vehicles actual roll and pitch

29 GCS - Post flight analysisExcessive Vibration

30 GCS - Post flight analysisCompass Interference Look for patterns between mag_field and throttle

31 GCS - Post flight analysisGPS Glitches

32 GCS - Post flight analysisPower brown-outs, if APM voltage varies by more than 0.15V, or goes below 4.7V

33 Practical Session 2 (20min)Logfile Analysis Find a logfile generated by SITL(./ArduPlane/logs) for the bin file For more interesting data: stability/14536 Two options for Analysis tool (choose one) Mission Planner MAVExplorer Check GPS GPS.Nsats and GPS.HDop messages Check Vibration IMU.AccX, IMU.AccY, IMU.AccZ messages

34 GCS - Inflight MonitoringAPM outputs a lot of telemetry data How to watch all this in realtime?

35 GCS - Inflight MonitoringDecide which data is important May vary depending on mission phase Speed, Altitude during takeoff and landing Moving map during mission

36 GCS - Inflight MonitoringThings to typically monitor Speed Altitude UAV Position (longitude/latitude) along with waypoints Battery voltage Telemetry link quality Any error messages Anything that, if not detected in a short time, could result in a crash

37 GCS - Inflight MonitoringHave backup plans for common failure scenarios Practice! In SITL In test flights Consider having multiple GCS stations to split the workload

38 The End! Flight Planning Logfile analysis Inflight monitoring