Multi-Robot Graph SLAM using LIDAR Simulation Package

This repository contains a world and launch files for testing the the Multi-Robot Graph SLAM Framework in a simulated environment using Gazebo. Tested on

• ROS2 humble and Gazebo Fortress
• ROS2 Jazzy and Gazebo Harmonic (minimal, see below), checkout branch gazebo_harmonic

Dependencies

This package depends on the following packages:

• Gazebo Fortress
• Gazebo Harmonic
• ros_gz

sudo apt install ros-humble-ros-gz # ROS2 JazzHumble sudo apt install ros-jazzy-ros-gz # ROS2 Jazzy

Usage for two robots in the marsyard2020 environment

The demo explained in this section can be checked out in this video on youtube:

1. Launch the world

Launch the world in gazebo with the following command. Note that the first call to gazebo might take a while, since it has to download the models of the fortress.

ros2 launch mrg_slam_sim marsyard2020.launch.py

2. Spawn the robots and start the ros_gz bridge and teleop node

Spawn two robots equipped with LIDAR sensors and bridge the sensor data to ROS2 topics. Also start the teleop_joystick node to control the first robot atlas with a joystick (xbox). This terminal has to be kept active.

ros2 launch mrg_slam_sim dual_robot_sim.launch.py # only for Gazebo Fortress at the moment

You should be able to control the first robot atlas with the joystick.

3. Control the robots via the terminal

If you don't have a joystick, you can disable the teleopjoystick node in the dual robot config by setting `enableteleop_joy` to false. Then you can control the robot with the keyboard using the following command:

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r __node:=teleop_twist_keyboard_node_atlas -r /cmd_vel:=/atlas/cmd_vel

Second robot bestla can be controlled with the keyboard in a new terminal using the following command:

ros2 run teleop_twist_keyboard teleop_twist_keyboard --ros-args -r __node:=teleop_twist_keyboard_node_bestla -r /cmd_vel:=/bestla/cmd_vel

4. Start two instances of the Multi-Robot Graph SLAM Framework

Now to test the Multi-Robot Graph SLAM Framework with the mrg_slam package. Run two instances of the slam algorithm as follows:

ros2 launch mrg_slam mrg_slam.launch.py model_namespace:=atlas x:=-15.0 y:=13.5 z:=1.1 # terminal 1 ros2 launch mrg_slam mrg_slam.launch.py model_namespace:=bestla x:=-15.0 y:=-13.0 z:=1.1 # terminal 2

Or use two instances of Multi-Robot Graph SLAM inside two docker containers. Make sure that the docker containers can communicate with the host machine. For example, environment variables like ROSLOCALHOSTONLY or ROSDOMAINID should not be set or should be correctly set. Then run the following commands:

docker run -it --rm --network=host --ipc=host --pid=host -e MODEL_NAMESPACE=atlas -e USE_SIM_TIME=true -e X=-15.0 -e Y=13.5 -e Z=1.1 --name atlas_slam mrg_slam # terminal 1 docker run -it --rm --network=host --ipc=host --pid=host -e MODEL_NAMESPACE=bestla -e USE_SIM_TIME=true -e X=-15.0 -e Y=-13.0 -e Z=1.1 --name bestla_slam mrg_slam # terminal 2

5. Visualize the results in rviz2

Move the robots and visualize the results in rviz2:

rviz2 -d /path/to/mrg_slam/rviz/mrg_slam.rviz --ros-args -p use_sime_time:=true

Additional use cases

Simulate a single robot without a namespace / robot name

Many packages use hard-coded frames like /base_link or /odom. If you want to test the Multi-Robot Graph SLAM Framework with a single robot without a namespace, you can use the singlerobotsim.launch.py launch file. After launching the gazebo world in step 1 above, you can spawn a single robot.

ros2 launch mrg_slam_sim single_robot_sim.launch.py # Gazebo Fortress & Harmonic

Simulate a single robot with a namespace / robot name

If you want to test the Multi-Robot Graph SLAM Framework with a single robot with a namespace, you need to set the robot_name parameter in the singlerobotmarsyard2020_sim.yaml file. After launching the gazebo world in step 1 above, you can spawn a single robot with a namespace.

ros2 launch mrg_slam_sim single_robot_sim.launch.py

Launch the world with any number of robots

Check out the config/multirobotsim.yaml file to set the robot_names, the initial poses, and the topics to bridge from gazebo to ROS2. Then you can spawn any number of robots and start bridging topics using the following command:

ros2 launch mrg_slam_sim multi_robot_sim.launch.py

Launch other worlds

At the moment there are two worlds available: marsyard2020 and rubicon. You can launch the rubicon world with the following command:

ros2 launch mrg_slam_sim rubicon.launch.py

To spawn two robots at the correct positions in the rubicon world, you can use the following command:

ros2 launch mrg_slam_sim dual_robot_sim.launch.py world:=rubicon # dual robot in rubicon world ros2 launch mrg_slam_sim single_robot_sim.launch.py world:=rubicon # single robot in rubicon world

Note that when you start an instance of the Multi-Robot Graph SLAM Framework, you have to set the correct initial position of the robot in the rubicon world. The initial poses can be found in the config folder.

ros2 launch mrg_slam mrg_slam.launch.py model_namespace:=atlas x:=-7.0 y:=0.0 z:=3.96 # terminal 1 ros2 launch mrg_slam mrg_slam.launch.py model_namespace:=bestla x:=0.0 y:=-15.0 z:=3.8 # terminal 2