Differential_drive_robot-Model

Creating a Simple Two Wheeled Mobile Robot using the Primitive shapes in URDF .

Packages

• differential_drive_robot_description
• differential_drive_robot_gazebo
• differential_drive_robot_control

Dependencies

• geometry_msgs
• rospy
• std_msgs

Package Explanation :

differential_drive_robot_description:

This package contains the urdf description of the robot which is used to do all kinds of simulation works.

differential_drive_robot_gazebo :

This package is used to deploy the robot model into the gazebo simulation world.

differential_drive_robot_control:

As the name suggests this package is used to control the motion of the robot. Alternatively we can also use rqt robot steering for motion control.

How to launch the robot ?

Create a workspace for example catkin_ws and paste all the three packages in the src folder

Run the command in terminal

catkin_make

The Robot model is designed using various xacro files found at ~catkin_ws/src/differential_drive_robot_description/urdf :

• differential_drive_robot.xacro - Main Robot description
• differentila_drive_robot.gazebo - Gazebo description
• xacro_variables.xacro - xacro variables description
• materials.xacro - Colors description

Visualization

To view the robot model in rviz :

Run the command in terminal

roslaunch differential_drive_robot_description rviz_visualize.launch

To view the robot model also in gazebo atmosphere :

Run the command in terminal

roslaunch differential_drive_robot_gazebo differential_drive_robot_rviz_gazebo.launch

Control

Now into the control part. We can control the robot motion using two methods,

• rqt robot steering
• differential_drive_robot_control package

Robot steering :

Run the command in terminal

rqt

In rqt we can find the robot steering under Plugins

Plugins-->Robot Tools-->Robot Steering

The robot steering appears in which we are able to change the linear and angluar motion velocity i.e., we are actually changing cmd_vel parameter .

differential_drive_robot_control :

In this package the motion is controlled using the keyboard. The corresponding script which is used for this purpose can be found at

~catkin_ws/src/differential_drive_robot_control/nodes/teleop.py

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 teleop.launch file.

Launching

Run the following commands in terminal :

• Start Rviz and Gazebo to visualize

roslaunch differential_drive_robot_gazebo differential_drive_robot_rviz_gazebo.launch

• Start the teleop:

roslaunch differential_drive_robot_control teleop.launch

You can find the end result >>here<<.