diff_drive_bot

This ROS package implements SLAM on a 2 wheeled differential drive robot to map an unknown environment. A joystick is used to teleoperate the robot in Gazebo. The map generated is then used for autonomous navigation using the ROS Navigation stack.

Demo Video \ Blog Post

Installation

1. Build package from source: navigate to the source folder of your catkin workspace and build this package using:

   $ git clone https://github.com/devanshdhrafani/diff_drive_bot.git
   $ cd ..
   $ catkin_make

2. Install Required dependencies:

   $ sudo apt-get install ros-melodic-dwa-local-planner
   $ sudo apt-get install ros-melodic-joy

Simultaneous Localization And Mapping (SLAM)

The package uses slam_gmapping to map the environment. For the purpose of this demonstration, we use the Gazebo simulation environment to move around the robot.

1. Load the robot in the Gazebo environment. Default model is the turtlebot3_house. You can change this from /worlds/mybot.world. To continue with default model:

   $ roslaunch diff_drive_bot gazebo.launch 

2. Launch the slam_gmapping node. This will also start rviz where you can visualize the map being created:

   $ roslaunch diff_drive_bot gmapping.launch

3. Move the robot around. If you have a Joystick, use:

    $ roslaunch diff_drive_bot joy_teleop_launch.launch

   OR teleop using keyboard:

    $ rosrun diff_drive_bot keyboard_teleop.py 

4. Move the robot in your environment till a satisfactory map is created.
5. Save the map using:

   $ rosrun map_server map_saver -f ~/test_map

6. Copy the map file to ~/diff_drive_bot/maps/ directory and edit the .yaml file to match the path.

Autonomous Navigation

This package uses the ROS Navigation stack to autonomously navigate through the map created using gmapping.

0. To use your generated map, edit /launch/amcl_move_base.launch and add map .yaml location and name to map_server node launch.
1. Load the robot in gazebo environment:

   $ roslaunch diff_drive_bot gazebo.launch 

2. Start the amcl, move_base and rviz nodes:

   $ roslaunch diff_drive_bot amcl_move_base.launch

3. In rviz, click on 2D Pose Estimate and set initial pose estimate of the robot.
4. To move to a goal, click on 2D Nav Goal to set your goal location and pose.

[Optional] Joystick Configuration

To make it easier to map environments, I added a joystick_teleop node to control the robot movement using my xbox controller. If you are using some other controller, you can easily map your buttons:

1. Install the ROS joy package: $ sudo apt-get install ros-melodic-joy
2. Connect your Jotstick to your machine and check if its detected: $ ls /dev/input/
3. If everything worked, your joystick should show up as jsX. In my case, it showed up as js1.
4. Go to /launch/joy_teleop_launch.launch and edit the dev parameter value to /dev/input/jsX.
5. Open the joy_teleop.py script in the /scripts/ folder.
6. Uncomment the print statements in the joyCallback() function.
7. Save and run the script using: $ roslaunch diff_drive_robot joy_teleop_launch.launch
8. You will see 2 arrays corresponding to the axes and buttons of your Joystick. Press each button/stick and find the index of your controls. Change the joy_teleop.py script with your respective axes.