Multibot

Multibot is a ROS Kinetic package that allows for the simulation of multiple turtlebots in Gazebo, each with their own navigation stack, sharing a common map, and all visualized in rviz. Be sure to check out the wiki.

Installation

First, open a terminal and create a catkin workspace by running the following:

mkdir -p catkin_ws/src
cd catkin_ws/src
catkin_init_workspace

We named our workspace catkin_ws, but this choice was arbitrary. Next clone the multibot repository:

git clone https://github.com/ept221/multibot.git

To get a list of top-level dependencies, run: rospack depends1 multibot. To view the complete dependency list, run: rospack depends multibot. To install all required dependencies, run:

rosdep update
rosdep install multibot

Then move up a directory and build the package:

cd ..
catkin_make

Next, add this line to your .bashrc file in your home directory to source the package.

source ~/catkin_ws/devel/setup.bash

Finally, restart your terminal and you should be ready to go.

Running the Package

To launch the package, run: roslaunch multibot start.launch. The main launch file start.launch has two optional commandline arguments: world_file, and map_file. If these are not provided, a default world and map will be loaded. To load a cusom world and file run: roslaunch multibot start.launch world_file:=customWorld.world map_file:=customMap.yaml, where customWorld.world and customMap.yaml are your custom files. Check out the /worlds and /maps directories to see other pre-made worlds/maps.

Adding Another Bot

To add another turtlebot to the system, open the start.launch file and insert the following after the map server node:

<include file="single.launch">
	
	<arg name="name" value="INSERT STRING HERE"/>
	
	<arg name="x_pose" value="INSERT FLOAT HERE"/>
	<arg name="y_pose" value="INSERT FLOAT HERE"/>
	<arg name="z_pose" value="INSERT FLOAT HERE"/>
	<arg name="R_pose" value="INSERT FLOAT HERE"/>
	<arg name="P_pose" value="INSERT FLOAT HERE"/>
	<arg name="Y_pose" value="INSERT FLOAT HERE"/>
	
	<arg name="x_pose_amcl" value="INSERT FLOAT HERE"/>
	<arg name="y_pose_amcl" value="INSERT FLOAT HERE"/>
	<arg name="Y_pose_amcl" value="INSERT FLOAT HERE"/>
	
</include>

where name is the unique string which shall identify the new robot, where x_pose, y_pose, and z_pose are floats giving the initial 3D cartesian coordinates of the robot in the Gazebo world, where R_pose, P_pose, and Y_pose are floats giving the initial role, pitch, and yaw of the robot in the Gazebo world, and where x_pose_amcl, y_pose_amcl, and Y_pose_amcl are floats giving the inital 2D cartesian coordinates and the yaw of the robot in the map used by the navigation stack.

The name argument is the only one that is required, and all others default to 0.0. Additionaly, if x_pose_amcl, y_pose_amcl, and Y_pose_amcl are not provided, they will default to x_pose, y_pose and Y_pose. The reason they are included is to account for a rotation in the map relative to the Gazebo world. For example, suppose you wanted to spawn a new robot at (1, 1) in the Gazebo world, but your map used for navigation was rotated 90 degrees counterclockwise. If you only set x_pose = 1.0, and y_pose = 1.0, then your robot would spawn at (1, 1) in the Gazebo world, but would appear at (1, -1) on the AMCL map (with respect to Gazebo co-ordinates). To account for the rotation of the AMCL map reletive to the Gazebo world, you would need to also set x_pose_amcl to -1.0 and y_pose_amcl to 1.0. (Technically you could leave out the y_pose_amcl, because in this case it does not differ from the initial Gazebo y_pose value, but it is still good practice to include it for clarity).

For more details, including installation instructions and rviz configuration, see multibot.wiki.