Merge pull request #551 from dronekit/hgw_dk_sitl_example_follow_me

Update follow_me example to use dk-sitl by default

docs/examples/follow_me.rst

@@ -51,54 +51,58 @@ Once you've done that:
        cd dronekit-python/examples/follow_me/
 
 
-#. Start the example, passing the :ref:`connection string <get_started_connect_string>` you wish to use in the ``--connect`` parameter:
+#. You can run the example against a simulator (DroneKit-SITL) by specifying the Python script without any arguments.
+   The example will download SITL binaries (if needed), start the simulator, and then connect to it:
 
    .. code-block:: bash
 
-       python follow_me.py --connect 127.0.0.1:14550
-       
+       python follow_me.py
 
-   .. note::
+   On the command prompt you should see (something like):
    
-       The examples uses the ``--connect`` parameter to pass the :ref:`connection string <get_started_connect_string>` into the script. 
-       The command above is used to connect to :ref:`SITL <sitl_setup>` running on the local Linux machine via UDP port 14550.
+   .. code:: bash
+
+       Starting copter simulator (SITL)
+       SITL already Downloaded.
+       Connecting to vehicle on: tcp:127.0.0.1:5760
+       >>> APM:Copter V3.4-dev (e0810c2e)
+       >>> Frame: QUAD
+       Link timeout, no heartbeat in last 5 seconds
+       Basic pre-arm checks
+       Waiting for GPS...: None
+       ...
+       Waiting for GPS...: None
+       Taking off!
+        Altitude:  0.019999999553
+        ...
+        Altitude:  4.76000022888
+       Reached target altitude
+       Going to: Location:lat=50.616468333,lon=7.131903333,alt=30,is_relative=True
+       ...
+       Going to: Location:lat=50.616468333,lon=7.131903333,alt=30,is_relative=True
+       Going to: Location:lat=50.616468333,lon=7.131903333,alt=30,is_relative=True
+       User has changed flight modes - aborting follow-me
+       Close vehicle object
+       Completed
+       
+   .. note:: 
 
+       The terminal output above was created using simulated GPS data 
+       (which is why the same target location is returned every time).
+       
+       To stop follow-me you can change the vehicle mode or do Ctrl+C
+       (on a real flight you can just change the mode switch on your 
+       RC transmitter). 
+      
 
-On the terminal you should see (something like):
+#. 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. 
 
+   For example, to connect to SITL running on UDP port 14550 on your local computer:
 
-.. code-block:: bash
-    
-    Connecting to vehicle on: 127.0.0.1:14550
-    >>> APM:Copter V3.4-dev (e0810c2e)
-    >>> Frame: QUAD
-    Link timeout, no heartbeat in last 5 seconds
-    Basic pre-arm checks
-    Waiting for GPS...: None
-    ...
-    Waiting for GPS...: None
-    Taking off!
-     Altitude:  0.019999999553
-     ...
-     Altitude:  4.76000022888
-    Reached target altitude
-    Going to: Location:lat=50.616468333,lon=7.131903333,alt=30,is_relative=True
-    ...
-    Going to: Location:lat=50.616468333,lon=7.131903333,alt=30,is_relative=True
-    Going to: Location:lat=50.616468333,lon=7.131903333,alt=30,is_relative=True
-    User has changed flight modes - aborting follow-me
-    Close vehicle object
-    Completed
-
- 
-To stop follow-me you can change the vehicle mode (on a real flight you can just change the mode switch on your RC transmitter). 
-
-.. note:: 
+   .. code-block:: bash
 
-    The terminal output above was created using simulated GPS data 
-    (which is why the same target location is returned every time). It was exited by changing
-    the mode from GUIDED to STABILIZE using MAVProxy.
-    
+       python follow_me.py --connect 127.0.0.1:14550
+   
 
     
 How does it work?

examples/follow_me/follow_me.py

@@ -18,15 +18,29 @@ import sys
 
 #Set up option parsing to get connection string
 import argparse  
-parser = argparse.ArgumentParser(description='Tracks GPS position of your computer (Linux only). Connects to SITL on local PC by default.')
-parser.add_argument('--connect', default='127.0.0.1:14550',
-                   help="vehicle connection target. Default '127.0.0.1:14550'")
+parser = argparse.ArgumentParser(description='Tracks GPS position of your computer (Linux only).')
+parser.add_argument('--connect', 
+                   help="vehicle connection target string. If not specified, SITL automatically started and used.")
 args = parser.parse_args()
 
+connection_string = args.connect
+sitl = None
+
+
+#Start SITL if no connection string specified
+if not args.connect:
+    print "Starting copter simulator (SITL)"
+    from dronekit_sitl import SITL
+    sitl = SITL()
+    sitl.download('copter', '3.3', verbose=True)
+    sitl_args = ['-I0', '--model', 'quad', '--home=-35.363261,149.165230,584,353']
+    sitl.launch(sitl_args, await_ready=True, restart=True)
+    connection_string = 'tcp:127.0.0.1:5760'
+
 
 # Connect to the Vehicle
-print 'Connecting to vehicle on: %s' % args.connect
-vehicle = connect(args.connect, wait_ready=True)
+print 'Connecting to vehicle on: %s' % connection_string
+vehicle = connect(connection_string, wait_ready=True)
 
 
 
@@ -44,8 +58,8 @@ def arm_and_takeoff(aTargetAltitude):
         
     print "Arming motors"
     # Copter should arm in GUIDED mode
-    vehicle.mode    = VehicleMode("GUIDED")
-    vehicle.armed   = True    
+    vehicle.mode = VehicleMode("GUIDED")
+    vehicle.armed = True    
 
     while not vehicle.armed:      
         print " Waiting for arming..."
@@ -102,4 +116,8 @@ except socket.error:
 print "Close vehicle object"
 vehicle.close()
 
+# Shut down simulator if it was started.
+if sitl is not None:
+    sitl.stop()
+
 print("Completed")