The ROS documentation can be found here.
These packages make use of the robotic simulator Gazebo, along with the Jackal robot description. Multiple Jackals are spawned and are able to be moved independently. The difference between this package and the Jackal package, is that multiple Jackals are able to be spawned without causing overlap. Significant amounts of code are from Clearpaths Jackal package, this just has minor changes.
If you only want to simulate one, then follow the guide. The problem is that it isn't scalable. They use the same transformation tree and some message names. You can see the problem yourself if you spawn two and have a look at the topics and TF tree.
The starting point for simulating the robots. Contains launch and config files.
Starts up a Gazebo session and launches robots using multi_jackal_base.
Example: roslaunch multi_jackal_tutorials one_jackal.launch.
Contains a single launch file that calls all other jackal components.
Launches the velocity controller plugin and robot controls.
Creates a plugin for publishing robot states and transformations. Loads a parameter that describes the robot for use in Gazebo.
Creates the localisation and move_base nodes.
Make sure the file multi_jackal_description/scripts/env_run is executable.
Example launch files can be found in multi_jackal_tutorials/launch. Gazebo and RVIZ
can be viewed with gzclient and roslaunch multi_jackal_tutorials rviz.launch.