Connect ROS-compatibale Drone To Robonomics Parachain. Part 1. Launch by Transaction

In this article we will show that with the help of Robonomics tools you can control any ROS-compatible device. We will find a random drone simulation package on the web and adjust it to run with Robonomics.Requirements:

  • Ubuntu 18.04 LTS
  • ROS Melodic + Gazebo + RViz (installation manual here)
  • Robonomics node (binary file) (download latest release here)

The entire process of coding this part of demo is presented in a video below.

1. Find a simulation

Let's surf the web. Google for ROS drone simulator. The first link will mostly likely show you the tum_simulator page on http://wiki.ros.org/tum_simulator

tum_simulator

It's pretty outdated, so we better find a fork for our system. Google for tum_simulator Ubuntu 18 Gazebo 9 fork. The first result is a GitHub repo with an appropriate package. Dowload it

mkdir -p drone_simulator_ws/src
cd drone_simulator_ws/src
git clone https://github.com/tahsinkose/sjtu-drone
cd ..
catkin build

Don’t forget to add source command to ~/.bashrc:

echo "source /home/$USER/drone_simulator_ws/devel/setup.bash" >> ~/.bashrc
source "~/.bashrc"

Now we can run the simulation to see what do we need to do to take the drone under parachain control.

roslaunch sjtu_drone simple.launch

2. Inspect ROS topics

When the simulation is runnung, in a new tab run the following command to see the list of topics used by the drone:

rostopic list

Let's take a look at /cmd_vel, /drone/takeoff and /drone/land:

rostopic info /cmd_vel
rostopic info /drone/takeoff
rostopic info /drone/land

topics_info

As may be seen, there should be messages of Twist and Empty types, they are parts of std_msgs and geometry_msgs, we'll use this in the controller. Shut the simulation for a while.

3. Download controller package

Globally, the main difference from the casual ROS robot controller is a block of code, which checks all the transactions in the network using Robonomics IO. The package itself is available on GitHub. Download it and build the workspace:

cd ~/drone_simulator_ws/src
git clone https://github.com/PaTara43/drone_simulator_controller
cd drone_simulator_controller/src
chmod +x *.py
cd ~/drone_simulator_ws/src
catkin build

4. Manage accounts in DAPP

Since we are testing, let's create a local robonomics network node with robonomics binary file:

./robonomics --dev

Important! Before next launches it is necessary to remove a directory db with

rm -rf /home/$USER/.local/share/robonomics/chains/dev/db

After a successful launch create accounts following this manual. Do not forget to save each account's seed and address! You will need them for transactions. Add these addresses, seeds and path to robonomics binary file to file config.config in robonomics_ws/src/robonomics_sample_controller/src. Transfer some money (units) to these accounts:

balances

5. Launching the drone under parachain control

Up to now the only thing running should be the robonomics local node. In a separate terminal launch drone simulation:

roslaunch sjtu_drone simple.launch

Run the script:

rosrun drone_simulator_controller drone_sample_controller.py

launched_drone

Now you can send a transaction triggering the drone to start flying. To do so, you should use the Robonomics IO write subcommand of robonomics binary file:

echo "ON" | ./robonomics io write launch -r <DRONE_ADDRESS> -s <EMPLOYER’S_KEY>

Where <DRONE_ADDRESS> and <EMPLOYER’S_KEY> are replaced with previously saved strings accordingly. You should see the log "Taking Off" and the drone should start flying:

flying

That's how any ROS-compatible robot can be controlled by Robonomics parachain control. Proceed to part 2 to learn more

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