tello_driver

1. Overview

Communicating with the Tello drone can be done either using official Tello SDK or one of the unofficial libraries. The unofficial libraries originated from the reverse-engineering the raw packages broadcasted by the Tello. This ROS package is build on top of the unofficial TelloPy library. The TelloPy library is used at this moment since it offers more functionalities than the official Tello SDK or any other unofficial library.

Developing of the tello_driver ROS package is inspired by tello_driver, which by now diverged considerately from the original work. Furthermore, development of this ROS package pursues not to modify the TelloPy library, but instead apply any modification or addition to the ros_driver package in an encapsulated manner. This prevents breaking functionalities when updating the TelloPy library.

Installation

ROS distribution

Binary release from the ROS repository:

• Kinetic: $ sudo apt install ros-kinetic-tello-driver

Build from source

• $ cd <CATKIN_WS/SRC>
• $ git clone --recursive https://github.com/appie-17/tello_driver.git
• $ cd ..
• $ catkin_make
• $ source devel/setup.bash

Prerequisites

pip3 install av==6.0
sudo apt-get install libavdevice-dev
sudo apt-get install libavfilter-dev
sudo apt-get install libavfilter-extra
sudo apt-get install libavfilter6

sudo apt-get install ros-melodic-joy
sudo apt-get install ros-melodic-camera-info-manager
sudo apt-get install ros-melodic-camera-info-manager-py 
sudo apt-get install ros-melodic-codec-image-transport

Launch

• Turn on Tello drone
• Connect to drone's WiFi access point (TELLO_XXXXXX)
• $ roslaunch tello_driver tello_node.launch
• $ roslaunch tello_driver joy_teleop.launch

2. Nodes

2.1 tello_driver_node

Main node running as interface for the TelloPy library

Subscribed topics

• /tello/cmd_vel geometry_msgs/Twist
• /tello/emergency std_msgs/Empty
• /tello/fast_mode std_msgs/Empty
• /tello/flattrim std_msgs/Empty
• /tello/flip std_msgs/Uint8
• /tello/land std_msgs/Empty
• /tello/palm_land std_msgs/Empty
• /tello/takeoff std_msgs/Empty
• /tello/manual_takeoff std_msgs/Empty
• /tello/throw_takeoff std_msgs/Empty

Published topics

• /tello/camera/camera_info sensor_msgs/CameraInfo
• /tello/image_raw sensor_msgs/Image
• /tello/imag/raw/h264 h264_image_transport/H264Packet
• /tello/odom nav_msgs/Odometry
• /tello/imu sensor_msgs/Imu
• /tello/status tello_driver/TelloStatus

Services

TODO

Parameters

• ~/tello_driver_node/connect_timeout_sec
• ~/tello_driver_node/fixed_video_rate
• ~/tello_driver_node/local_cmd_client_port
• ~/tello_driver_node/local_vid_server_port
• ~/tello_driver_node/stream_h264_video
• ~/tello_driver_node/tello_cmd_server_port
• ~/tello_driver_node/tello_ip
• ~/tello_driver_node/vel_cmd_scale
• ~/tello_driver_node/video_req_sps_hz
• ~/tello_driver_node/altitude_limit
• ~/tello_driver_node/attitude_limit
• ~/tello_driver_node/low_bat_threshold

2.2 gamepad_teleop_node

Converting gamepad input controls from joy_node to commands for tello_driver_node

Subscribed topics

• /joy sensor_msgs/Joy
• /tello/agent_cmd_vel_in geometry_msgs/Twist

Published topic

• /tello/cmd_vel geometry_msgs/Twist
• /tello/emergency std_msgs/Empty
• /tello/fast_mode std_msgs/Empty
• /tello/flattrim std_msgs/Empty
• /tello/flip std_msgs/Uint8
• /tello/land std_msgs/Empty
• /tello/palm_land std_msgs/Empty
• /tello/takeoff std_msgs/Empty
• /tello/throw_takeoff std_msgs/Empty

Services

None

Parameters

2.3 joy_node

Receive input from gamepad controller and publish into sensor_msgs/Joy message

Subscribed topics

None

Published topics

• /joy sensor_msgs/Joy

Services

None

Parameters

• ~/joy_node/deadzone
• ~/joy_node/dev

3. Troubleshooting

• No more video output after reconnect
  Relaunch the tello_driver_node to continue the video stream after WiFi reconnection. Only an issue when using PyAV to decode h264 video instead of ROS codec_image_transport.

4. Notes

• Stream raw video
  Depends on PyAV package: $ pip install av --user

  Installation of PyAV on Ubuntu 16.04 requires ffmpeg of at least version 3:

  $ sudo add-apt-repository ppa:jonathonf/ffmpeg-3
$ sudo apt update && sudo apt install ffmpeg

5. Work-in-progress

6. License