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Update flight_replay docs and also to use standard takeoff function
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‎docs/examples/flight_replay.rst‎

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@@ -2,22 +2,21 @@
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Example: Flight Replay
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=========================
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This example requests a past flight from Droneshare, and then writes the recorded path to the vehicle as mission waypoints.
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For safety reasons, the altitude for the waypoints is set to 30 meters (irrespective of the recorded height).
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.. note::
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The mission is not actually run by this code - though it easily could be by taking off and putting the vehicle into
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AUTO mode.
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This example creates and runs a waypoint mission using position information in a TLOG file.
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You can specify which mission to replay using a parameter when starting the script (for example, to replay your own local flights).
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By default the code gets the public `Droneshare mission with ID 101 <http://www.droneshare.com/mission/101>`_.
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The log used in this example contains around 2700 points. We reduce this to a smaller number
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(that is able to fit on the autopilot) by taking 100 points that are evenly spread across the range.
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After 60 seconds the mission is artificially ended by setting the mode to RTL (return to launch).
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.. figure:: flight_replay_example.png
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:width: 50%
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Droneshare Mission #101
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Mission generated from log
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.. note::
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A more detailed example might determine the best points for the mission
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by mapping the path to lines and spline curves.
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Running the example
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The example can be run as described in :doc:`running_examples` (which in turn assumes that the vehicle
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and DroneKit have been set up as described in :ref:`installing_dronekit`).
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If you're using a simulated vehicle, remember to :ref:`disable arming checks <disable-arming-checks>` so
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that the example can run.
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In summary, after cloning the repository:
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#. Navigate to the example folder as shown:
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.. code-block:: bash
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cd dronekit-python/examples/flight_replay/
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#. Start the example, passing the :ref:`connection string <get_started_connect_string>`
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you wish to use in the ``--connect`` parameter and specifying the mission to replay.
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#. You can run the example against a simulator (DroneKit-SITL) by specifying the Python script without any arguments.
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The example will download SITL binaries if needed, start the simulator, and then connect to it:
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.. code-block:: bash
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python flight_replay.py --connect 127.0.0.1:14550 --mission_id 101
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python flight_replay.py
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.. note::
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On the command prompt you should see (something like):
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The ``--connect`` parameter above connects to SITL on udp port 127.0.0.1:14550, while
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``--mission_id`` specifies we're replaying mission 101. Both of these are the default
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values for the parameters, and may be omitted.
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.. code:: bash
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Generating waypoints from tlog...
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Generated 96 waypoints from tlog
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Starting copter simulator (SITL)
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SITL already Downloaded.
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Connecting to vehicle on: tcp:127.0.0.1:5760
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>>> APM:Copter V3.3 (d6053245)
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>>> Frame: QUAD
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>>> Calibrating barometer
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>>> Initialising APM...
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>>> barometer calibration complete
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>>> GROUND START
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Uploading 96 waypoints to vehicle...
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Arm and Takeoff
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Waiting for vehicle to initialise...
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>>> flight plan received
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Waiting for arming...
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...
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Waiting for arming...
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>>> ARMING MOTORS
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>>> GROUND START
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Waiting for arming...
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>>> Initialising APM...
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Waiting for arming...
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>>> ARMING MOTORS
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Taking off!
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Altitude: 0.010000 < 28.500000
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Altitude: 0.020000 < 28.500000
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...
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Altitude: 26.150000 < 28.500000
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Altitude: 28.170000 < 28.500000
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Reached target altitude of ~30.000000
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Starting mission
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Distance to waypoint (1): 6.31671220061
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Distance to waypoint (1): 5.54023406731
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>>> Reached Command #1
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Distance to waypoint (2): 4.05805003875
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...
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Distance to waypoint (2): 4.66600036548
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>>> Reached Command #2
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Distance to waypoint (3): 1.49371523482
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Distance to waypoint (3): 0.13542601646
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Distance to waypoint (3): 0.708432959397
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>>> Reached Command #3
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Distance to waypoint (4): 3.29161427437
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Distance to waypoint (4): 3.63454331996
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Distance to waypoint (4): 2.89070828637
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>>> Reached Command #4
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Distance to waypoint (5): 0.955857968149
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>>> Reached Command #5
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>>> Reached Command #6
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>>> Reached Command #7
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...
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>>> Reached Command #42
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Distance to waypoint (42): 7.6983209285
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...
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Distance to waypoint (43): 6.05247510021
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>>> Reached Command #43
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Distance to waypoint (43): 4.80180763387
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>>> Reached Command #44
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Distance to waypoint (44): 3.89880557617
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...
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Distance to waypoint (45): 11.0865559753
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>>> Reached Command #45
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Distance to waypoint (46): 9.45419808223
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...
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Distance to waypoint (46): 13.2676499949
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Return to launch
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Close vehicle object
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Completed...
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.. tip::
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It is more interesting to watch the example run on a map than the console. The topic :ref:`viewing_uav_on_map`
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explains how to set up *Mission Planner* to view a vehicle running on the simulator (SITL).
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.. tip::
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It is more interesting to watch the example above on a map than the console. The topic :ref:`viewing_uav_on_map`
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explains how to set up *Mission Planner* to view a vehicle running on the simulator (SITL).
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#. You can run the example against a specific connection (simulated or otherwise) by passing the :ref:`connection string <get_started_connect_string>` for your vehicle in the ``--connect`` parameter.
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On the command prompt you should see (something like):
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For example, to connect to SITL running on UDP port 14550 on your local computer:
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.. code-block:: bash
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Connecting to vehicle on: 127.0.0.1:14550
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>>> APM:Copter V3.3 (d6053245)
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>>> Frame: QUAD
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JSON downloaded...
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Generating 95 waypoints from replay...
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Close vehicle object
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Completed...
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.. code-block:: bash
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python simple_goto.py --connect 127.0.0.1:14550
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How it works
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============
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The example requests the web server for representative points from the flight, parses the JSON response
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and uses that data to generate 100 waypoints. These are then sent to the vehicle.
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The example parses the **flight.tlog** file for position information. It then selects about 100
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points that are evenly spread across the log and uploads them as a mission.
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For safety reasons, the altitude for the waypoints is set to 30 meters (irrespective of the recorded height).
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Getting the points
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------------------
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83-
The following simple function asks for the droneshare flight data:
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The following simple function parses the tlog for points and then
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returns 100 evenly points from the collected set.
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.. code:: python
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def download_messages(mission_id, max_freq = 1.0):
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"""Download a public mission from droneshare (as JSON)"""
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f = urllib.urlopen("%s/api/v1/mission/%s/messages.json?max_freq=%s&api_key=%s" % (api_server, mission_id, max_freq, api_key))
90-
j = json.load(f, object_hook=_decode_dict)
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f.close()
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return j
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Some comments:
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def position_messages_from_tlog(filename):
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"""
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Given telemetry log, get a series of waypoints approximating the previous flight
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"""
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# Pull out just the global position msgs
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messages = []
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mlog = mavutil.mavlink_connection(filename)
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while True:
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try:
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m = mlog.recv_match(type=['GLOBAL_POSITION_INT'])
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if m is None:
159+
break
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except Exception:
161+
break
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# ignore we get where there is no fix:
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if m.lat == 0:
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continue
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messages.append(m)
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# Shrink the # of pts to be lower than the max # of wpts allowed by vehicle
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num_points = len(messages)
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max_points = 99
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if num_points > max_points:
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step = int(math.ceil((float(num_points) / max_points)))
172+
shorter = [messages[i] for i in xrange(0, num_points, step)]
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messages = shorter
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return messages
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* ``max_freq`` is used to throttle the messages found in the raw flight data to a lower message rate
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* ``_decode_dict`` is a utility function found on stack overflow which extracts usable strings from unicode encoded JSON (see `flight_replay.py <https://github.com/hamishwillee/dronekit-python/blob/master/examples/flight_replay/flight_replay.py>`_ for its implementation).
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Setting the new waypoints

‎docs/examples/flight_replay_example.png‎

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Loading

‎examples/flight_replay/flight_replay.py‎

Lines changed: 45 additions & 27 deletions
Original file line numberDiff line numberDiff line change
@@ -68,7 +68,9 @@ def distance_to_current_waypoint():
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return distancetopoint
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def position_messages_from_tlog(filename):
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"""Given telemetry log, get a series of wpts approximating the previous flight"""
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"""
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Given telemetry log, get a series of wpts approximating the previous flight
73+
"""
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# Pull out just the global position msgs
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messages = []
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mlog = mavutil.mavlink_connection(filename)
@@ -92,10 +94,48 @@ def position_messages_from_tlog(filename):
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shorter = [messages[i] for i in xrange(0, num_points, step)]
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messages = shorter
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return messages
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def arm_and_takeoff(aTargetAltitude):
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"""
101+
Arms vehicle and fly to aTargetAltitude.
102+
"""
103+
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# Don't try to arm until autopilot is ready
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while not vehicle.is_armable:
106+
print " Waiting for vehicle to initialise..."
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time.sleep(1)
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# Set mode to GUIDED for arming and takeoff:
110+
while (vehicle.mode.name != "GUIDED"):
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vehicle.mode = VehicleMode("GUIDED")
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time.sleep(0.1)
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# Confirm vehicle armed before attempting to take off
115+
while not vehicle.armed:
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vehicle.armed = True
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print " Waiting for arming..."
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time.sleep(1)
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print " Taking off!"
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vehicle.simple_takeoff(aTargetAltitude) # Take off to target altitude
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# Wait until the vehicle reaches a safe height
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# before allowing next command to process.
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while True:
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requiredAlt = aTargetAltitude*0.95
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#Break and return from function just below target altitude.
128+
if vehicle.location.global_relative_frame.alt>=requiredAlt:
129+
print " Reached target altitude of ~%f" % (aTargetAltitude)
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break
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print " Altitude: %f < %f" % (vehicle.location.global_relative_frame.alt,
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requiredAlt)
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time.sleep(1)
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96136
print("Generating waypoints from tlog...")
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messages = position_messages_from_tlog(args.tlog)
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print "Generated %d waypoints from tlog" % len(messages)
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print " Generated %d waypoints from tlog" % len(messages)
99139
if len(messages) == 0:
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print("No position messages found in log")
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exit(0)
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cmds.clear()
125165
for i in xrange(0, len(messages)):
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pt = messages[i]
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print "Point: %d %d" % (pt.lat, pt.lon,)
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#print "Point: %d %d" % (pt.lat, pt.lon,)
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lat = pt.lat
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lon = pt.lon
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# To prevent accidents we don't trust the altitude in the original flight, instead
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143183
print("Uploading %d waypoints to vehicle..." % len(messages))
144184
cmds.upload()
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146-
# Set mode to STABILISE for arming and takeoff:
147-
while (vehicle.mode.name != "GUIDED"):
148-
vehicle.mode = VehicleMode("GUIDED")
149-
time.sleep(0.1)
150-
151-
while not vehicle.armed:
152-
print("Arming vehicle")
153-
vehicle.armed = True
154-
print "Waiting for arming..."
155-
time.sleep(1)
186+
print "Arm and Takeoff"
187+
arm_and_takeoff(30)
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157-
print("Taking off")
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aTargetAltitude = 30.0
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vehicle.simple_takeoff(aTargetAltitude)
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# Wait until the vehicle reaches a safe height
162-
while True:
163-
requiredAlt = aTargetAltitude*0.95
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#Break and return from function just below target altitude.
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if vehicle.location.global_relative_frame.alt>=requiredAlt:
166-
print "Reached target altitude of ~%f" % (aTargetAltitude)
167-
break
168-
print " Altitude: %f < %f" % (vehicle.location.global_relative_frame.alt,
169-
requiredAlt)
170-
time.sleep(1)
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print "Starting mission"
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