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A line follower project for NXP MR-B3RB (Mobile Robotics Buggy 3 Rev B) for participants of AIM 2024. |
This software can run on the B3RB and Gazebo Simulator.
- Gazebo Simulator: Development and testing environment used for B3RB.
- It's used to simulate the B3RB with it's various sensors and capabilities.
- It's used to simulate the track with it's various challenges and obstacles.
This project is based on the autopilot project - CogniPilot (AIRY Release for B3RB).
- Refer the CogniPilot AIRY Dev Guide for information about it's various components.
- Cranium: A ROS workspace that performs higher level computation for CogniPilot.
- On the hardware B3RB, it runs on NavQPlus board (Mission Computer).
- On the Gazebo Simulator, it runs on the Ubuntu Linux machine.
- This project includes a ROS2 Python package that integrates into the Cranium workspace.
- This project (b3rb_ros_line_follower) should be moved to ~/cognipilot/cranium/src.
- This is the only folder that participants would modify and submit for the regional finale.
{% hint style="info" %} _**~/congnipilot/cranium/src/b3rb_ros_line_follower**_ is the only folder that the participants have to modify an submit for the Regional Finale {% endhint %}
This project contains three python scripts which provide a framework for a line follower application.
- b3rb_ros_edge_vectors: It creates vectors on the edges of the road in front of the rover.
- The image captured from the front camera is used for detecting edges of the road.
- Cases based on number of vectors created:
- 0: When neither left or right edge of the road is detected.
- 1: When only 1 out of left or right edge of the road is detected.
- 2: When both left and right edge of the road are detected.
- Both the vectors's mid-point can't lie in either the left or right half.
- One vector must lie in the left half and the other must lie in the right half.
- The vectors are published to the topic "/edge_vectors".
- Message type: "~/cognipilot/cranium/src/synapse_msgs/msg/EdgeVectors.msg".
- We assume the part of road that is very close to the rover is relevant for decision making.
- Hence, only the bottom 40% of the image is analyzed for edges of the road.
- This threshold could be modified by changing the value of lower_image_height.
- Hence, the y-coordinates of the vectors ∈ [40% of image height, image height].
- Hence, only the bottom 40% of the image is analyzed for edges of the road.
- Please feel free to modify this file if you feel that would improve the vector creation.
- b3rb_ros_line_follower: Contains framework for running the rover using edge vectors.
- Write your code in the "edge_vectors_callback" function for line follower application.
- This callback is called whenever a new set of vectors are published on "/edge_vectors".
- Utilize "rover_move_manual_mode" for moving the rover. Refer its docstring for explanation.
- Write your code in the "lidar_callback" function for obstacle avoidance and ramp detection.
- This callback is called whenever a new set of data is published on "/scan".
- Please note that this file contains a generic implementation of line follower functionality.
- You are allowed to modify or implement a different method to improve performance.
- Write your code in the "edge_vectors_callback" function for line follower application.
- b3rb_ros_object_recog: Contains framework for recognizing objects on the track.
- Write your code in the "camera_image_callback" function.
The below diagram depicts how various essential ROS-2 nodes are communicating with each other:
In above graph:
- The ovals are the nodes.
- The rectangles are the topics.
- The outer rectangles are namespaces of the topics.
- The arrows represent publishers and subscriptions of nodes.