Simple Line Follower

About

This repository demonstrates a basic line-following robot which uses a Proportional-Derivative Controller.

This ROS 2 package is used to demonstrate these examples :

• Code which is tough to test (Ex : naive_line_follower.cpp)
• Code which is easy to test (Ex : line_follower.cpp)
• Basic unit-tests taking the line follower as an example (Ex : test_line_follower_basic.cpp)
• Basic unit-tests taking the naive line follower as an example (Ex : test_naive_line_follower.cpp)
• Good unit tests taking the line follower as an example (Ex : test_line_follower_good.cpp)

Dependencies

• Ubuntu 22.04
• ROS 2 Humble
• Ignition Gazebo(Fortress)
• bcr_bot

Installation

1. Clone this repository

   git clone git@github.com:ggupta9777/simple_line_follower.git

2. Clone bcr_bot

   git clone git@github.com:blackcoffeerobotics/bcr_bot.git

3. Install dependencies using rosdep:

   rosdep install --from-paths src -y --ignore-src

4. Build the packages with test config(Note : The `--cmake-args`` used above are to enable code coverage analysis)

   colcon build --symlink-install --cmake-args -DCMAKE_BUILD_TYPE=Debug   -DCMAKE_CXX_FLAGS="--coverage" -DCMAKE_CXX_OUTPUT_EXTENSION_REPLACE=ON

Run instructions

1. Launch bcr_bot

   ros2 launch bcr_bot gz.launch.py \
       camera_enabled:=True \
       stereo_camera_enabled:=False \
       two_d_lidar_enabled:=True \
       position_x:=0.0 \
       position_y:=0.0  \
       orientation_yaw:=0.0 \
       odometry_source:=world \
       world_file:=empty.sdf

2. Run the line follower node

   • Run the line_follower_node

     ros2 run simple_line_follower line_follower_node --ros-args --params-file src/simple_line_follower/config/params.yaml

   • Run the naive_line_follower_node

     ros2 run simple_line_follower naive_line_follower_node --ros-args --params-file src/simple_line_follower/config/params.yaml

Running Tests

• Run the test scripts(Note : The --event-handler=console_direct+ argument is used to show the logs of the testing process)

    colcon test --event-handler=console_direct+

Generate Code Coverage

1. Use lcov to generate code coverage

   lcov --capture --directory build/ --output-file code_coverage_report.info

2. Generate an HTML file to showcase the code coverage report

   genhtml code_coverage_report.info --output-directory html_code_coverage_report

3. Open the code coverage on your browser

   sensible-browser html_code_coverage_report/index.html

Topics

• /bcr_bot/cmd_vel : This topic is used to publish velocity messages to the bot in Gazebo
• /bcr_bot/odom : This topic is used to obtain odometry information regarding the bot

Demo

This is a demo of the bot following a line defined by the waypoints : (0, 1, 0) and (5, 1, 0)