Reactive wall following robot with laser scanner sensor

This project implements a wall-following algorithm in python for differential drive 2 wheeled robot with a laser scanner sensor using the Robot Operating System 2 (ROS2) libraries, Ignition Gazebo as simulator and Python as programming language. The proposed wall-following algorithm makes a robot wander at random until a wall is found, then follows the wall - through an implemented control to keep a constant distance from it in the outside of a question mark shaped “?" wall, stoping at the bottom dot.

Getting Started

These instructions will get you a copy of the project up and running on your local machine for development and testing purposes.

Test Environment

• Ubuntu 22.04 - Operating System
• ROS2 Iron - Set of software libraries and tools used to build and interact with the robot
• Ignition Gazebo Fortress - Tool used to simulation
• Python 3.10.12 - Programming language

Setup

After clone the project navigate to the project folder

cd ros2_ws/

Run colcon build check here how to setup colcon

colcon build

Launch the simulation

Return to the project folder

ros2 launch IR_assignment1_controller simulation_launch.py

Running with multiple terminals

To run the with multiple terminals it will be necessary to use 4 (or 5) different terminals. Follow the steps starting at project root folder.

First Terminal

Do not close this terminal

1. Run the command to change to the world workspace:

cd ros2_ws/src/IR_assignment1_controller/worlds/

2. Launch the simulation world:

ign gazebo environment.sdf 

Second Terminal

Do not close this terminal

1. Run the command to setup the lidar bridge:

ros2 run ros_gz_bridge parameter_bridge lidar@sensor_msgs/msg/LaserScan[ignition.msgs.LaserScan

Third Terminal

Do not close this terminal

1. Run the command to setup the command bridge:

ros2 run ros_gz_bridge parameter_bridge cmd_vel@geometry_msgs/msg/Twist]ignition.msgs.Twist

Fourth Terminal

Do not close this terminal

1. Change to the base workspace:

cd ../../..

2. Build the environment:

colcon build

3. Run the wall-following script:

ros2 run IR_assignment1_controller wall_follower 

Fifth Terminal

1. Run rviz2 to see the lidar measurments:

rviz2

2. Select add at the bottom left, and then select laserscaner and click Ok.

3. Change the fized frame parameter to: "vehicle_blue/chassis/gpu_lidar"

Authors

• Tiago Fonseca up202302320