ball-chaser-bot

Overview

These are two packages containing a Gazebo environment with a skid-steer drive robot equipped with a camera and a Hokuyo lidar. There is one node for commanding robot joints and a second one for processing the camera image, detecting round objects, and sending the appropriate velocities commands.

License

The source code is released under an MIT license.

Author/Maintainer: George Sotirchos

The ball-chaser-bot package has been tested under ROS Noetic on Ubuntu 20.04. This is experimental, personal project code, and possibly subject to frequent changes with any need for explanation disclaimed.

Installation

Building from Source

Dependencies

• Robot Operating System (ROS) (middleware for robotics),
• opencv-python (Open Source Computer Vision Library)

Building

To build from source, clone the latest version from this repository into your catkin workspace and compile the package using

cd catkin_ws/src
git clone https://github.com/gsotirchos/ball-chaser-bot
cd ../
rosdep install --from-paths . --ignore-src
catkin_make

Usage

1. Start the Gazebo environment containing the robot:

   roslaunch my_robot world.launch

2. Start the ball_chaser and the process_image_opencv nodes:

   roslaunch ball_chaser ball_chaser.launch

   Or to use the "dumb" process_image node (without OpenCV):

   roslaunch ball_chaser ball_chaser.launch use_opencv:=false

Launch files

• my_robot/launch/world.launch: A Gazebo simulation is opened with 4-wheeled skid-steer drive robot equipped with a camera and a Hokuyo lidar spawned in an office environment containing some balls, along with an RViz window showing the camera image and the lidar measurements.

• ball_chaser/launch/ball_chase.launch: Starts the drive_bot and process_image_opencv/process_image nodes.

  Arguments:

  • use_opencv: Whether to use the OpenCV image processing node or the "dumb" one.
    Default: true (Optional)

Nodes

drive_bot

Provides a service for publishing drive commands to the robots actuators.

Published Topics

• /cmd_vel (geometry_msgs/Twist)

  The requested linear_x and angular_z velocities for the robot wheel joints.

Services

• ~command_robot (ball_chaser/DriveToTarget)

  Publishes the requested the requested linear_x and angular_z velocities to /cmd_vel topic.

  rosservice call /ball_chaser/command_robot "linear_x: 0.0
  angular_z: 0.0"  # with the newline
  

process_image_opencv

Processes the camera image published at /camera/rgb/image_raw and requests the appropriate drive commands via the ~command_robot service.

Subscribed Topics

• /camera/rgb/image_raw (sensor_msgs/Image)

  The robot-mount camera image input.

Bugs & Feature Requests

Please report bugs and request features using the Issue Tracker.

ROS: http://www.ros.org
Gazebo plugin: http://gazebosim.org/tutorials?tut=ros_gzplugins#SkidSteeringDrive
OpenCV: https://docs.opencv.org/master/