• translated_sha: 95b39d747851dd01c1fe5d36b24e59ec865e323e
  • Using DroneKit to communicate with PX4
    • 配置DroneKit
    • 完整的任务示例

    translated_page: https://github.com/PX4/Devguide/blob/master/en/dronekit/example.md

    translated_sha: 95b39d747851dd01c1fe5d36b24e59ec865e323e

    Using DroneKit to communicate with PX4

    DroneKit 可以帮助创建强大的无人机应用。这些应用运行在无人机的协同计算机上,通过执行计算密集但又需要低延迟的任务(计算机视觉)来增强飞控计算机。

    DroneKit和PX4目前致力于获得完全兼容。截止DroneKit-python 2.2.0,仅提供任务处理和状态监控这样的基本支持。

    配置DroneKit

    首先,从当前主分支安装DroneKit-python

    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

    创建一个新的python文件并导入DroneKit, pymavlink和基本模块

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

    连接到无人机或模拟器的MAVLink端口

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

    显示一些基本的状态信息

    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

    完整的任务示例

    下面的python脚本文件给出了使用DroneKit和PX4的完整任务范例。目前还不完全支持模式切换,因此我们发送自定义的模式切换指令。

    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. ################################################################################################
    9. # Import DroneKit-Python
    10. from dronekit import connect, Command, LocationGlobal
    11. from pymavlink import mavutil
    12. import time, sys, argparse, math
    13. ################################################################################################
    14. # Settings
    15. ################################################################################################
    16. connection_string = '127.0.0.1:14540'
    17. MAV_MODE_AUTO = 4
    18. # https://github.com/PX4/Firmware/blob/master/Tools/mavlink_px4.py
    19. # Parse connection argument
    20. parser = argparse.ArgumentParser()
    21. parser.add_argument("-c", "--connect", help="connection string")
    22. args = parser.parse_args()
    23. if args.connect:
    24. connection_string = args.connect
    25. ################################################################################################
    26. # Init
    27. ################################################################################################
    28. # Connect to the Vehicle
    29. print "Connecting"
    30. vehicle = connect(connection_string, wait_ready=True)
    31. def PX4setMode(mavMode):
    32. vehicle._master.mav.command_long_send(vehicle._master.target_system, vehicle._master.target_component,
    33. mavutil.mavlink.MAV_CMD_DO_SET_MODE, 0,
    34. mavMode,
    35. 0, 0, 0, 0, 0, 0)
    36. def get_location_offset_meters(original_location, dNorth, dEast, alt):
    37. """
    38. Returns a LocationGlobal object containing the latitude/longitude `dNorth` and `dEast` metres from the
    39. specified `original_location`. The returned Location has the same `alt` value
    40. as `original_location`.
    41. The function is useful when you want to move the vehicle around specifying locations relative to
    42. the current vehicle position.
    43. The algorithm is relatively accurate over small distances (10m within 1km) except close to the poles.
    44. For more information see:
    45. http://gis.stackexchange.com/questions/2951/algorithm-for-offsetting-a-latitude-longitude-by-some-amount-of-meters
    46. """
    47. earth_radius=6378137.0 #Radius of "spherical" earth
    48. #Coordinate offsets in radians
    49. dLat = dNorth/earth_radius
    50. dLon = dEast/(earth_radius*math.cos(math.pi*original_location.lat/180))
    51. #New position in decimal degrees
    52. newlat = original_location.lat + (dLat * 180/math.pi)
    53. newlon = original_location.lon + (dLon * 180/math.pi)
    54. return LocationGlobal(newlat, newlon,original_location.alt+alt)
    55. ################################################################################################
    56. # Listeners
    57. ################################################################################################
    58. home_position_set = False
    59. #Create a message listener for home position fix
    60. @vehicle.on_message('HOME_POSITION')
    61. def listener(self, name, home_position):
    62. global home_position_set
    63. home_position_set = True
    64. ################################################################################################
    65. # Start mission example
    66. ################################################################################################
    67. # wait for a home position lock
    68. while not home_position_set:
    69. print "Waiting for home position..."
    70. time.sleep(1)
    71. # Display basic vehicle state
    72. print " Type: %s" % vehicle._vehicle_type
    73. print " Armed: %s" % vehicle.armed
    74. print " System status: %s" % vehicle.system_status.state
    75. print " GPS: %s" % vehicle.gps_0
    76. print " Alt: %s" % vehicle.location.global_relative_frame.alt
    77. # Change to AUTO mode
    78. PX4setMode(MAV_MODE_AUTO)
    79. time.sleep(1)
    80. # Load commands
    81. cmds = vehicle.commands
    82. cmds.clear()
    83. home = vehicle.location.global_relative_frame
    84. # takeoff to 10 meters
    85. wp = get_location_offset_meters(home, 0, 0, 10);
    86. 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)
    87. cmds.add(cmd)
    88. # move 10 meters north
    89. wp = get_location_offset_meters(wp, 10, 0, 0);
    90. 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)
    91. cmds.add(cmd)
    92. # move 10 meters east
    93. wp = get_location_offset_meters(wp, 0, 10, 0);
    94. 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)
    95. cmds.add(cmd)
    96. # move 10 meters south
    97. wp = get_location_offset_meters(wp, -10, 0, 0);
    98. 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)
    99. cmds.add(cmd)
    100. # move 10 meters west
    101. wp = get_location_offset_meters(wp, 0, -10, 0);
    102. 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)
    103. cmds.add(cmd)
    104. # land
    105. wp = get_location_offset_meters(home, 0, 0, 10);
    106. 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)
    107. cmds.add(cmd)
    108. # Upload mission
    109. cmds.upload()
    110. time.sleep(2)
    111. # Arm vehicle
    112. vehicle.armed = True
    113. # monitor mission execution
    114. nextwaypoint = vehicle.commands.next
    115. while nextwaypoint < len(vehicle.commands):
    116. if vehicle.commands.next > nextwaypoint:
    117. display_seq = vehicle.commands.next+1
    118. print "Moving to waypoint %s" % display_seq
    119. nextwaypoint = vehicle.commands.next
    120. time.sleep(1)
    121. # wait for the vehicle to land
    122. while vehicle.commands.next > 0:
    123. time.sleep(1)
    124. # Disarm vehicle
    125. vehicle.armed = False
    126. time.sleep(1)
    127. # Close vehicle object before exiting script
    128. vehicle.close()
    129. time.sleep(1)