• rospy
• roscpp
• geometry_msgs

• myrobot_description specifies the entire robot structure as links and joints and can launch the model in rviz.
• myrobot_gazebo launches the model in the gazebo environment and contains different simulation worlds.
• myrobot_control launches the model in the gazebo environment where the robot motion can be commanded by the keyboard.

In ~/catkin_ws/src/myrobot_description/urdf, there are four files:

• myrobot.xacro: primary file that loads the other three files and contains only URDF items like joints and links
• myrobot.gazebo: contains gazebo-specific labels that are wrapped within gaz
• materials.xacro: maps strings to colors
• macros.xacro: macros to help simplify

Load the Gazebo simulator and rviz in separate terminals using the following commands:

roslaunch myrobot_gazebo myrobot_world.launch
roslaunch myrobot_description myrobot_rviz.launch

On a new terminal use the following command to make the robot drive incessantly along a circle of user-defined diameter. (Here diameter = 4 m. So, radius = 2m. Thus linear and angular velocities are set accordingly)

rostopic pub /cmd_vel geometry_msgs/Twist "linear:
  x: 0.2
  y: 0.0
  z: 0.0
angular:
  x: 0.0
  y: 0.0
  z: 0.1"

Can also run using script. The ~/catkin_ws/src/myrobot_gazebo/scripts contains the circle_mode.py node.

• Launch the gazebo simulator using the following command:

roslaunch myrobot_gazebo myrobot_world.launch

• Start the circle_mode node:

rosrun myrobot_gazebo circle_mode.py

The ~/catkin_ws/src/myrobot_gazebo/scripts contains the square_mode.py node. It draws a square of 0.4m side.

• Launch the gazebo simulator using the following command:

roslaunch myrobot_gazebo myrobot_world.launch

• Start the square_mode node:

rosrun myrobot_gazebo square_mode.py

This method is not perfect as the robot is way off from the point it started, after completing the square. Using motion planning the action can be made accurate.

The ~/catkin_ws/src/myrobot_control/scripts folder contains the myrobot_key node, which is the teleop node. There is already a standard teleop node implementation available (for the turtlebot), we simply reused the node. Then a remapping is done from the turtlebot_teleop_keyboard/cmd_vel to /cmd_vel of our robot in the keyboard_teleop.launch file.

• Launch the gazebo simulator with complete simulation settings using the following command:

roslaunch myrobot_gazebo myrobot_gazebo_full.launch

• Start the teleop node:

roslaunch myrobot_control keyboard_teleop.launch

• Start RViz to visualize the robot state:

rosrun rviz rviz