PX4-MAVROS-Simulation-Setup

This Repo covers creating a reliable and tested PX4-MAVROS environment with Gazebo setup for your drone simulations. This branch is mainly for ROS1 (tested on melodic and noetic). You can find the ROS2 branch here. Hardware implementation with Pixhawk and Jetson Nano for ROS1 is also illustrated here.

System Requirements

• Ubuntu Linux 20.04 LTS
• ROS Noetic

Setup

Here we are using a two-workspace setup for our PX4-MAVROS environment. catkin_ws is for the PX4 Firmware and catkin_w_s is for MAVROS and MAVLink. You can have your own nomenclature for the workspaces, just be sure to correctly run the commands that mention the name. Also, your .bashrc scripts has to change accordingly.

PX4

First we need the PX4 Firmware that mimics Pixhawk in simulation. By the end of this section, you should have your drone up and running in Gazebo.

• Create the workspace for PX4 Firmware:

mkdir catkin_ws
cd catkin_ws

• Clone the Firmware right inside the workspace:

git clone https://github.com/PX4/Firmware.git --recursive
cd Firmware

• Run the setup file (this may take a while, ~20 minutes) and reboot your pc:

bash ./Tools/setup/ubuntu.sh
sudo reboot now

• Launch the simulation:

cd catkin_ws/Firmware
make px4_sitl gazebo

• This will take a few seconds and a gazebo window will open with iris quadcopter placed at the origin. In terminal you will see that the command is running (means its not terminated), press Enter you will see:

>px4 _

• So when this appears type commander takeoff after px4 so it should look like:

>px4 commander takeoff_

• The drone will take off to standard takeoff altitude of 2.5 m. Next you can try landing the drone by typing:

>px4 commander land_

• The drone should land safely. Caution: Don't terminate the process by using Ctrl+C, it might hang your pc. Use the following command to exit the simulation:

>px4 shutdown_

First step of setup is complete.

MAVROS

Now we move onto MAVROS and MAVLINK installation

• If you haven't installed catkin tools while installing ros , install it using the following command:

sudo apt-get install python3-catkin-tools python3-rosinstall-generator -y

• Initialize the workspace for MAVROS:

mkdir -p ~/catkin_w_s/src
cd ~/catkin_w_s
catkin init
wstool init src

While inside the workspace, do the following:

• Install MAVLink : (command is distro specific, so be careful)

rosinstall_generator --rosdistro noetic mavlink | tee /tmp/mavros.rosinstall

• Install latest version of MAVROS :

rosinstall_generator --upstream-development mavros | tee -a /tmp/mavros.rosinstall

• If you don't have geographicLib installed through the last command, run:

sudo ./src/mavros/mavros/scripts/install_geographiclib_datasets.sh

• Create the workspace and add dependencies:

wstool merge -t src /tmp/mavros.rosinstall
wstool update -t src -j4
rosdep install --from-paths src --ignore-src -y

• Finally, build the workspace:

catkin build
source devel/setup.bash

Configure .bashrc

• Source and export required directories in .bashrc to be able to run executables from anywhere. Add the following lines at the bottom of your .bashrc script:

source ~/catkin_ws/Firmware/Tools/simulation/gazebo-classic/setup_gazebo.bash ~/catkin_ws/Firmware/ ~/catkin_ws/Firmware/build/px4_sitl_default
source ~/catkin_w_s/devel/setup.bash
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:~/catkin_ws/Firmware
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:~/catkin_ws/Firmware/Tools/simulation/gazebo-classic/sitl_gazebo-classic

• Now let's test if everything is working fine. First go to your home directory, and then run the following command:

cd
roslaunch px4 mavros_posix_sitl.launch

• This should launch a Gazebo environment with the iris quadcopter same as before, only this time you can run rostopic list in a separate terminal and you should be able to see all /mavros topics and more.
• You can run >px4 commander takeoff and rostopic echo /mavros/state to get some insights to the various modes that mavros has for specific set of utilities.

Our PX4-MAVROS environment is finally set up. Now we can move on to creating our own custom packages and scripts.

Custom Package

• Any package that deals with mavros and px4 dependencies should be created at ~/catkin_w_s/src. So ls should show mavlink mavros my_custom_pkg.
• To create your package, run:

catkin_create_pkg my_custom_pkg rospy roscpp mavros_msgs geometry_msgs tf2

• This will create a package with rospy, roscpp, mavros_msgs, geometry_msgs tf2 as dependencies.
• In src you can create a scripts folder to house your executable files.
• Source your package by putting the following in your .bashrc:

source ~/catkin_w_s/devel/setup.bash ~/catkin_w_s/src/my_custom_pkg/src/scripts

• To run your scripts, first build the workspace again with catkin build.
• Then launch the PX4-MAVROS Gazebo simulation with roslaunch px4 mavros_posix_sitl.launch.
• Finally run rosrun my_custom_pkg my_executable_script.
• For getting started you can follow the Offboard example available at PX4 Docs.
  • For python example, visit here.
  • For cpp example, visit here.