Mobile Robot Controller

This is a ROS Package for controlling mobile robots. It was inspired by and borrows a lot of ideas from the Control of Mobile Robots MOOC by Dr. Magnus Egerstedt.

• TurtleBot3 Waffle is used as the robot.
• Hybrid Automata with Go To Goal, Obstacle Avoidance and Follow Wall modes governed by SlidingModeSwitch are implemented.

Getting Started

Prerequisites

• ROS Melodic with Gazebo-9 (Desktop-Full Install)
• TurtleBot3 package for ROS Melodic.

Installation

1. Clone the contents of this repository to the src/ folder of your catkin workspace.
2. Navigate to your catkin workspace folder.
3. Invoke catkin_make in your terminal at the root of the catkin workspace.
4. Check if the compilation was successful by invoking rospack find mobile_robot_controller in your terminal. It should print out the location of the mobile_robot_controller folder.

Demo

*=Goal Point

You can try out the package by following these steps:

1. Load the Gazebo Environment. By default, the world is empty. You can add obstacles using the insert tab in Gazebo or changing the turtlebot3_world.world file in the worlds/ folder.

   $ roslaunch mobile_robot_controller turtlebot3_world.launch
   

2. Start the mr-controller node. The default goal location is [3.0,-2.0]. You can change this by modifying the variable x_d and y_d in the mr-controller.cpp file.

   $ rosrun mobile_robot_controller mr-controller_node
   

3. Watch the robot go to the goal location and avoiding obstacles on the way.

Usage

Although this package is written for the Turtlebot3 Waffle robot, it can be easily modified for controlling any custom mobile robot.

• The package has 2 main files: mr-controller.cpp and hybridAutomata.h.
• The mr-controller.cpp file is responsible for the ROS side of the controller. It subscribes to the /scan topic for the Lidar Scan and /odom topic for the robot odometry. The node publishes on velocity commands on the /cmd_vel topic. All topics use the standard ROS message types. For a custom robot, these are the topics that need to be set.
• The hybridAutomata.h file is where the switching logic resides. The class hybrid_automata is what you can modify to implement your own custom switching logic.

Authors

• Devansh Dhrafani

To-Do

• Add demo clips.
• Add examples for wall following.
• Change PID control from hardcode to ROS PID package.
• Add support for custom goal points using Rviz: 2D Nav Goal.

Acknowledgements

My wholehearted thanks to Georgia Tech and Coursera for putting up this amazing walkthrough course on controlling mobile robots. Dr. Magnus Egerstedt has done a brilliant job in explaining each concept part by part and finally combining them for getting sense of the bigger picture. I definitely recommend this course to any robotics enthusiast.