/CarND-Capstone-System-Integration

Udacity Self-Driving Car Engineer

Primary LanguageCMakeMIT LicenseMIT

Project: System Integration(Capstone Project)

Udacity - Self-Driving Car NanoDegree

Introduction
Running Instructions

In this project, we'll be writing ROS nodes to implement core functionality of the autonomous vehicle system, including traffic light detection, control, and waypoint following! We will test our code using a simulator that mimics the functionality on Carla.

System Architecture Diagram

Code structure

(path_to_project_repo)/ros/src/tl_detector/

This package contains the traffic light detection node: tl_detector.py. This node takes in data from the /image_color, /current_pose, and /base_waypoints topics and publishes the locations to stop for red traffic lights to the /traffic_waypoint topic.

The /current_pose topic provides the vehicle's current position, and /base_waypoints provides a complete list of waypoints the car will be following.

(path_to_project_repo)/ros/src/waypoint_updater/

This package contains the waypoint updater node: waypoint_updater.py. The purpose of this node is to update the target velocity property of each waypoint based on traffic light and obstacle detection data. This node will subscribe to the /base_waypoints, /current_pose, /obstacle_waypoint, and /traffic_waypoint topics, and publish a list of waypoints ahead of the car with target velocities to the /final_waypoints topic.

(path_to_project_repo)/ros/src/twist_controller/

Carla is equipped with a drive-by-wire (dbw) system, meaning the throttle, brake, and steering have electronic control. This package contains the files that are responsible for control of the vehicle: the node dbw_node.py and the file twist_controller.py, along with a pid and lowpass filter that you can use in our implementation. The dbw_node subscribes to the /current_velocity topic along with the /twist_cmd topic to receive target linear and angular velocities. Additionally, this node will subscribe to /vehicle/dbw_enabled, which indicates if the car is under dbw or driver control. This node will publish throttle, brake, and steering commands to the /vehicle/throttle_cmd, /vehicle/brake_cmd, and /vehicle/steering_cmd topics.

(path_to_project_repo)/ros/src/styx/

A package that contains a server for communicating with the simulator, and a bridge to translate and publish simulator messages to ROS topics.

(path_to_project_repo)/ros/src/styx_msgs/

A package which includes definitions of the custom ROS message types used in the project.

(path_to_project_repo)/ros/src/waypoint_loader/

A package which loads the static waypoint data and publishes to /base_waypoints.

(path_to_project_repo)/ros/src/waypoint_follower/

A package containing code from Autoware which subscribes to /final_waypoints and publishes target vehicle linear and angular velocities in the form of twist commands to the /twist_cmd topic.

References

Acknowledgments

Big thank you to Udacity for providing the template code and simulator for this project.