chase_ball

Robot which detects and chases a white-coloured ball using camera and lidar sensors.

Structure

The repository contains two packages as follows.

my_robot

This package holds a robot, a white ball, and the surrounding world. The robot is a differential drive robot designed with URDF (Unified Robot Description Format). A Gazebo plugin controls the robot’s differential drive as well as the camera and lidar sensors which are used to detect the white ball.

ball_chaser

This package contains two nodes responsible for detecting the ball and driving towards it. The process_image node analyses the robot's camera image to detect the presence and location of the white ball. If a ball exists, the node requests a service via the client to drive the robot towards it. The drive_bot node provides a service to drive the robot by controlling its linear and angular velocities.

Screenshots

Building

Prerequisites/Dependencies: Gazebo and ROS.

With the prerequisites met, source global ros:

$ source /opt/ros/<your_ros_version>/setup.bash

Create a catkin workspace:

$ mkdir -p catkin_ws/src && cd catkin_ws

Clone the driver:

$ git clone https://github.com/barrymulvey/gazebo_world.git src/gazebo_world

Install dependencies:

$ sudo apt update -qq
$ rosdep update
$ rosdep install --from-paths src --ignore-src -y

Build the workspace:

$ catkin_make

Activate the workspace:

$ source devel/setup.bash

Launch the world file in Gazebo:

$ roslaunch my_robot world.launch

Open a new terminal and launch the nodes to detect and chase the white ball:

$ cd catkin_ws
$ source devel/setup.bash
$ roslaunch ball_chaser ball_chaser.launch

Directory Structure

.Project                           # Chase Ball Project
├── my_robot                       # my_robot package                   
│   ├── launch                     # launch folder for launch files   
│   │   ├── robot_description.launch
│   │   ├── world.launch
│   ├── meshes                     # meshes folder for sensors
│   │   ├── hokuyo.dae
│   ├── urdf                       # urdf folder for xarco files
│   │   ├── my_robot.gazebo
│   │   ├── my_robot.xacro
│   ├── worlds                     # world folder for world files
│   │   ├── myworld.world
│   ├── CMakeLists.txt             # compiler instructions
│   ├── package.xml                # package info
├── ball_chaser                    # ball_chaser package                   
│   ├── launch                     # launch folder for launch files   
│   │   ├── ball_chaser.launch
│   ├── src                        # source folder for C++ scripts
│   │   ├── drive_bot.cpp
│   │   ├── process_images.cpp
│   ├── srv                        # service folder for ROS services
│   │   ├── DriveToTarget.srv
│   ├── CMakeLists.txt             # compiler instructions
│   ├── package.xml                # package info                  
└──