Double SLS Controller

Video available at https://www.youtube.com/watch?v=GrKxC1hDQOI

WSL2-Based Environment Installation

0. Install WSL2 & Ubuntu 20.04

Follow the guide at https://docs.px4.io/main/en/dev_setup/dev_env_windows_wsl.html.

1. Install PX4-Autopilot v1.13.2

Follow the guide at https://docs.px4.io/main/en/contribute/git_examples.html#get-a-specific-release, or

1. Clone PX4-Autopilot repository and navigate to the directory

git clone https://github.com/PX4/PX4-Autopilot.git
cd ~/PX4-Autopilot

2. Check out code for desired tag

git checkout v1.13.2

3. Update submodules

make submodulesclean

4. Install Dependencies

cd ~
bash ./PX4-Autopilot/Tools/setup/ubuntu.sh

5. Restart WSL2

exit
wsl --shutdown
wsl

6. Install Dependencies

sudo apt-get install protobuf-compiler libeigen3-dev libopencv-dev -y

7. Build PX4 SITL

cd ~/PX4-Autopilot
make px4_sitl

2. Install ROS Noetic & MAVROS

Follow the guide at https://docs.px4.io/main/en/ros/mavros_installation.html, or

1. Retrieve the latest package lists and install

sudo apt update
sudo apt upgrade

2. Setup ROS sources list

sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list'

3. Setup the keys

sudo apt install curl # if you haven't already installed curl
curl -s https://raw.githubusercontent.com/ros/rosdistro/master/ros.asc | sudo apt-key add -

4. Install ROS

sudo apt install ros-noetic-desktop-full

5. Setup environment

echo "source /opt/ros/noetic/setup.bash" >> ~/.bashrc
source ~/.bashrc

6. Install and initialized dependencies

sudo apt install python3-rosdep python3-rosinstall python3-rosinstall-generator python3-wstool build-essential
sudo apt install python3-rosdep
sudo rosdep init
rosdep update

7. Install ROS python tools

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

8. Create ROS workspace folder

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

9. Install MAVLink

# We use the Kinetic reference for all ROS distros as it's not distro-specific and up to date
rosinstall_generator --rosdistro kinetic mavlink | tee /tmp/mavros.rosinstall

10. Install MAVROS with source installation

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

Modify the "version" tag of MAVROS entry in ~/catkin_ws/src/.rosinstall to make it look like below:

- git:
    local-name: mavlink
    uri: https://github.com/mavlink/mavlink-gbp-release.git
    version: release/kinetic/mavlink/2021.3.3-1
- git:
    local-name: mavros
    uri: https://github.com/mavlink/mavros.git
    version: 1.16.0  

Then install the dependency:

wstool merge -t src /tmp/mavros.rosinstall
wstool update -t src -j4

3. Install Gazebo Link Attacher

cd catkin_ws/src  
git clone https://github.com/pal-robotics/gazebo_ros_link_attacher.git  
cd ..
catkin build

4. Install Double SLS Controller

cd ~/catkin_ws/src
git clone https://github.com/ANCL/double_sls_controller.git --recursive
cd ..
catkin build

5. Move the Link Attacher Script

sudo cp ~/catkin_ws/src/double_sls_controller/scripts/attach_sls.py ~/catkin_ws/src/gazebo_ros_link_attacher/scripts/attach_sls.py
chmod +x ~/catkin_ws/src/gazebo_ros_link_attacher/scripts/attach_sls.py

6. Install XMLStarlet if not already done

sudo apt install xmlstarlet

7. Modify /.bashrc

sudo vim ~/.bashrc

add following contents:

# For ROS Noetic
source /opt/ros/noetic/setup.bash
source ~/catkin_ws/devel/setup.bash

# For Gazebo 11
export GAZEBO_PLUGIN_PATH=$GAZEBO_PLUGIN_PATH:/usr/lib/x86_64-linux-gnu/gazebo-11/plugins
export GAZEBO_MODEL_PATH=$GAZEBO_MODEL_PATH:~/catkin_ws/src/double_sls_controller/models

# For PX4 v1.13.2
source ~/PX4-Autopilot/Tools/setup_gazebo.bash ~/PX4-Autopilot ~/PX4-Autopilot/build/px4_sitl_default
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:~/PX4-Autopilot
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:~/PX4-Autopilot/Tools/sitl_gazebo

8. Install QGroundControl (QGC)

Preparations

# in a new terminal
sudo usermod -a -G dialout $USER
sudo apt-get remove modemmanager -y
sudo apt install gstreamer1.0-plugins-bad gstreamer1.0-libav gstreamer1.0-gl -y
sudo apt install libqt5gui5 -y
sudo apt install libfuse2 -y

Download QGC AppImage

# in a new terminal
cd ~
wget https://d176tv9ibo4jno.cloudfront.net/latest/QGroundControl.AppImage

Install and run

chmod +x ./QGroundControl.AppImage
./QGroundControl.AppImage

Enable virtual joystick:
Important: Cannot takeoff without this step!
Application Settings > General > Check the Virtual Joystick checkbox.

Run DSLS SITL

1. Launch PX4 SITL

# in a new terminal
roslaunch double_sls_controller double_px4vision_sls_world.launch

Note: There's a known graphical problem where one of the drones' graphic model is not generated properly in the Gazebo GUI. Please relaunch if this happens.

2. Attach the Drones and the Slung Load

# in a new terminal
rosrun gazebo_ros_link_attacher attach_sls.py

Then unpause the simulation:

3. Run QGroundControl

# in a new terminal
cd
./QGroundControl.AppImage

4. Launch Double SLS Contoller

# in a new terminal
roslaunch double_sls_controller double_sls_node.launch

Note: Sometimes the two drones may not switch mode and arm together. Please try relaunching if that happens.

5. Run Dynamic Reconfigure Gui

# in a new terminal
rosrun rqt_reconfigure rqt_reconfigure

• Move sliders to change gains and references
• Check tick-box "dea_preintegrate_enabled" to let controller states converge
• Check tick-box "dea_enabled" to enable DEA
• Check tick-box "mission_enabled" to start set-point and trajectory tracking mission