vehicle_state.py

"""
vehicle_state.py: Get and set vehicle state, parameter and channel-override information. 

It also demonstrates how to observe vehicle attribute (state) changes. 

Full documentation is provided at http://python.dronekit.io/examples/vehicle_state.html
"""

from droneapi.lib import VehicleMode
from pymavlink import mavutil
import time

# First get an instance of the API endpoint
api = local_connect()
# Get the connected vehicle (currently only one vehicle can be returned).
vehicle = api.get_vehicles()[0]

# Get all vehicle attributes (state)
print "\nGet all vehicle attribute values:"
print " Location: %s" % vehicle.location
print " Attitude: %s" % vehicle.attitude
print " Velocity: %s" % vehicle.velocity
print " GPS: %s" % vehicle.gps_0
print " Groundspeed: %s" % vehicle.groundspeed
print " Airspeed: %s" % vehicle.airspeed
print " Mount status: %s" % vehicle.mount_status
print " Battery: %s" % vehicle.battery
print " Rangefinder: %s" % vehicle.rangefinder
print " Rangefinder distance: %s" % vehicle.rangefinder.distance
print " Rangefinder voltage: %s" % vehicle.rangefinder.voltage
print " Mode: %s" % vehicle.mode.name    # settable
print " Armed: %s" % vehicle.armed    # settable


# Set vehicle mode and armed attributes (the only settable attributes)
print "Set Vehicle.mode=GUIDED (currently: %s)" % vehicle.mode.name 
vehicle.mode = VehicleMode("GUIDED")
vehicle.flush()  # Flush to guarantee that previous writes to the vehicle have taken place
while not vehicle.mode.name=='GUIDED' and not api.exit:  #Wait until mode has changed
    print " Waiting for mode change ..."
    time.sleep(1)

print "Set Vehicle.armed=True (currently: %s)" % vehicle.armed 
vehicle.armed = True
vehicle.flush()
while not vehicle.armed and not api.exit:
    print " Waiting for arming..."
    time.sleep(1)


# Show how to add and remove and attribute observer callbacks (using mode as example) 
def mode_callback(attribute):
    print " CALLBACK: Mode changed to: ", vehicle.mode.name

print "\nAdd mode attribute observer for Vehicle.mode" 
vehicle.add_attribute_observer('mode', mode_callback)	

print " Set mode=STABILIZE (currently: %s)" % vehicle.mode.name 
vehicle.mode = VehicleMode("STABILIZE")
vehicle.flush()

print " Wait 2s so callback invoked before observer removed"
time.sleep(2)

# Remove observer - specifying the attribute and previously registered callback function
vehicle.remove_attribute_observer('mode', mode_callback)	


#  Get Vehicle Home location ((0 index in Vehicle.commands)
print "\nGet home location" 
cmds = vehicle.commands
cmds.download()
cmds.wait_valid()
print " Home WP: %s" % cmds[0]


#  Get/Set Vehicle Parameters
print "\nRead vehicle param 'THR_MIN': %s" % vehicle.parameters['THR_MIN']
print "Write vehicle param 'THR_MIN' : 10"
vehicle.parameters['THR_MIN']=10
vehicle.flush()
print "Read new value of param 'THR_MIN': %s" % vehicle.parameters['THR_MIN']


# Overriding an RC channel
# NOTE: CHANNEL OVERRIDES may be useful for simulating user input and when implementing certain types of joystick control. 
#DO NOT use unless there is no other choice (there almost always is!)
print "\nOverriding RC channels for roll and yaw"
vehicle.channel_override = { "1" : 900, "4" : 1000 }
vehicle.flush()
print " Current overrides are:", vehicle.channel_override
print " Channel default values:", vehicle.channel_readback  # All channel values before override

# Cancel override by setting channels to 0
print " Cancelling override"
vehicle.channel_override = { "1" : 0, "4" : 0 }
vehicle.flush()


## Reset variables to sensible values.
print "\nReset vehicle attributes/parameters and exit"
vehicle.mode = VehicleMode("STABILIZE")
vehicle.armed = False
vehicle.parameters['THR_MIN']=130
vehicle.flush()