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DroneKit로 PX4와 통신하기

DroneKit는 무인 항공기용 프로그램에 강력한 기능을 갖추도록 도와줍니다. 이 프로그램은 UAV의 보조 컴퓨터에서 실행하며, 처리 집약적 저지연 연결이 필요한 작업을 수행하여 오토파일럿의 능력(또는 기능, 예: 컴퓨터 비전)을 확장합니다.

DroneKit과 PX4는 현재 완전한 호환성을 갖추는 중입니다. DroneKit-python 2.2.0에서는 임무 처리와 기체 감시등 기본 기능을 지원합니다.

DroneKit와 PX4 설치

DroneKit-python을 현재 마스터 브랜치에서 끌어와 설치하십시오.

  1. git clone https://github.com/dronekit/dronekit-python.git
  2. cd ./dronekit-python
  3. sudo python setup.py build
  4. sudo python setup.py install

새 파이썬 파일을 만들어 DroneKit, pymavlink, 기본 모듈을 끌어(import)오십시오.

  1. # Import DroneKit-Python
  2. from dronekit import connect, Command, LocationGlobal
  3. from pymavlink import mavutil
  4. import time, sys, argparse, math

드론 또는 모의시험 환경(예: jMAVSim)의 MAVLink 포트로 연결하십시오.

  1. # Connect to the Vehicle
  2. print "Connecting"
  3. connection_string = '127.0.0.1:14540'
  4. vehicle = connect(connection_string, wait_ready=True)

일부 기본 정보를 표시해보십시오.

  1. # Display basic vehicle state
  2. print " Type: %s" % vehicle._vehicle_type
  3. print " Armed: %s" % vehicle.armed
  4. print " System status: %s" % vehicle.system_status.state
  5. print " GPS: %s" % vehicle.gps_0
  6. print " Alt: %s" % vehicle.location.global_relative_frame.alt

전체 임무 예제

다음 파이썬 스크립트에서는 DroneKit와 PX4를 활용한 전체 임무 예제를 보여줍니다. DroneKit에서 상태 전환은 완전히 지원하지 않기에, 개별 상태 전환 명령을 따로 보냅니다.

  1. ################################################################################################
  2. # @File DroneKitPX4.py
  3. # Example usage of DroneKit with PX4
  4. #
  5. # @author Sander Smeets <sander@droneslab.com>
  6. #
  7. # Code partly based on DroneKit (c) Copyright 2015-2016, 3D Robotics.
  8. ################################################################################################
  10. # Import DroneKit-Python
  11. from dronekit import connect, Command, LocationGlobal
  12. from pymavlink import mavutil
  13. import time, sys, argparse, math
  16. ################################################################################################
  17. # Settings
  18. ################################################################################################
  20. connection_string       = '127.0.0.1:14540'
  21. MAV_MODE_AUTO   = 4
  22. # https://github.com/PX4/PX4-Autopilot/blob/master/Tools/mavlink_px4.py
  25. # Parse connection argument
  26. parser = argparse.ArgumentParser()
  27. parser.add_argument("-c", "--connect", help="connection string")
  28. args = parser.parse_args()
  30. if args.connect:
  31.     connection_string = args.connect
  34. ################################################################################################
  35. # Init
  36. ################################################################################################
  38. # Connect to the Vehicle
  39. print "Connecting"
  40. vehicle = connect(connection_string, wait_ready=True)
  42. def PX4setMode(mavMode):
  43.     vehicle._master.mav.command_long_send(vehicle._master.target_system, vehicle._master.target_component,
  44.                                                mavutil.mavlink.MAV_CMD_DO_SET_MODE, 0,
  45.                                                mavMode,
  46.                                                0, 0, 0, 0, 0, 0)
  50. def get_location_offset_meters(original_location, dNorth, dEast, alt):
  51.     """
  52.     Returns a LocationGlobal object containing the latitude/longitude `dNorth` and `dEast` metres from the
  53.     specified `original_location`. The returned Location adds the entered `alt` value to the altitude of the `original_location`.
  54.     The function is useful when you want to move the vehicle around specifying locations relative to
  55.     the current vehicle position.
  56.     The algorithm is relatively accurate over small distances (10m within 1km) except close to the poles.
  57.     For more information see:
  58.     http://gis.stackexchange.com/questions/2951/algorithm-for-offsetting-a-latitude-longitude-by-some-amount-of-meters
  59.     """
  60.     earth_radius=6378137.0 #Radius of "spherical" earth
  61.     #Coordinate offsets in radians
  62.     dLat = dNorth/earth_radius
  63.     dLon = dEast/(earth_radius*math.cos(math.pi*original_location.lat/180))
  65.     #New position in decimal degrees
  66.     newlat = original_location.lat + (dLat * 180/math.pi)
  67.     newlon = original_location.lon + (dLon * 180/math.pi)
  68.     return LocationGlobal(newlat, newlon,original_location.alt+alt)
  74. ################################################################################################
  75. # Listeners
  76. ################################################################################################
  78. home_position_set = False
  80. #Create a message listener for home position fix
  81. @vehicle.on_message('HOME_POSITION')
  82. def listener(self, name, home_position):
  83.     global home_position_set
  84.     home_position_set = True
  88. ################################################################################################
  89. # Start mission example
  90. ################################################################################################
  92. # wait for a home position lock
  93. while not home_position_set:
  94.     print "Waiting for home position..."
  95.     time.sleep(1)
  97. # Display basic vehicle state
  98. print " Type: %s" % vehicle._vehicle_type
  99. print " Armed: %s" % vehicle.armed
  100. print " System status: %s" % vehicle.system_status.state
  101. print " GPS: %s" % vehicle.gps_0
  102. print " Alt: %s" % vehicle.location.global_relative_frame.alt
  104. # Change to AUTO mode
  105. PX4setMode(MAV_MODE_AUTO)
  106. time.sleep(1)
  108. # Load commands
  109. cmds = vehicle.commands
  110. cmds.clear()
  112. home = vehicle.location.global_relative_frame
  114. # takeoff to 10 meters
  115. wp = get_location_offset_meters(home, 0, 0, 10);
  116. cmd = Command(0,0,0, mavutil.mavlink.MAV_FRAME_GLOBAL_RELATIVE_ALT, mavutil.mavlink.MAV_CMD_NAV_TAKEOFF, 0, 1, 0, 0, 0, 0, wp.lat, wp.lon, wp.alt)
  117. cmds.add(cmd)
  119. # move 10 meters north
  120. wp = get_location_offset_meters(wp, 10, 0, 0);
  121. cmd = Command(0,0,0, mavutil.mavlink.MAV_FRAME_GLOBAL_RELATIVE_ALT, mavutil.mavlink.MAV_CMD_NAV_WAYPOINT, 0, 1, 0, 0, 0, 0, wp.lat, wp.lon, wp.alt)
  122. cmds.add(cmd)
  124. # move 10 meters east
  125. wp = get_location_offset_meters(wp, 0, 10, 0);
  126. cmd = Command(0,0,0, mavutil.mavlink.MAV_FRAME_GLOBAL_RELATIVE_ALT, mavutil.mavlink.MAV_CMD_NAV_WAYPOINT, 0, 1, 0, 0, 0, 0, wp.lat, wp.lon, wp.alt)
  127. cmds.add(cmd)
  129. # move 10 meters south
  130. wp = get_location_offset_meters(wp, -10, 0, 0);
  131. cmd = Command(0,0,0, mavutil.mavlink.MAV_FRAME_GLOBAL_RELATIVE_ALT, mavutil.mavlink.MAV_CMD_NAV_WAYPOINT, 0, 1, 0, 0, 0, 0, wp.lat, wp.lon, wp.alt)
  132. cmds.add(cmd)
  134. # move 10 meters west
  135. wp = get_location_offset_meters(wp, 0, -10, 0);
  136. cmd = Command(0,0,0, mavutil.mavlink.MAV_FRAME_GLOBAL_RELATIVE_ALT, mavutil.mavlink.MAV_CMD_NAV_WAYPOINT, 0, 1, 0, 0, 0, 0, wp.lat, wp.lon, wp.alt)
  137. cmds.add(cmd)
  139. # land
  140. wp = get_location_offset_meters(home, 0, 0, 10);
  141. cmd = Command(0,0,0, mavutil.mavlink.MAV_FRAME_GLOBAL_RELATIVE_ALT, mavutil.mavlink.MAV_CMD_NAV_LAND, 0, 1, 0, 0, 0, 0, wp.lat, wp.lon, wp.alt)
  142. cmds.add(cmd)
  144. # Upload mission
  145. cmds.upload()
  146. time.sleep(2)
  148. # Arm vehicle
  149. vehicle.armed = True
  151. # monitor mission execution
  152. nextwaypoint = vehicle.commands.next
  153. while nextwaypoint < len(vehicle.commands):
  154.     if vehicle.commands.next > nextwaypoint:
  155.         display_seq = vehicle.commands.next+1
  156.         print "Moving to waypoint %s" % display_seq
  157.         nextwaypoint = vehicle.commands.next
  158.     time.sleep(1)
  160. # wait for the vehicle to land
  161. while vehicle.commands.next > 0:
  162.     time.sleep(1)
  165. # Disarm vehicle
  166. vehicle.armed = False
  167. time.sleep(1)
  169. # Close vehicle object before exiting script
  170. vehicle.close()
  171. time.sleep(1)