AWS DeepRacer navigation package

Overview

The AWS DeepRacer navigation ROS package creates the deepracer_navigation_node, which is part of the core AWS DeepRacer application and launches from the deepracer_launcher. For more information about the application and the components, see the aws-deepracer-launcher repository.

This node is responsible for collecting the reinforcement learning model inference results and mapping them to the servo message with throttle and steering angle values based on the action space for the particular model selected.

License

The source code is released under Apache 2.0.

Installation

Follow these instructions to install the AWS DeepRacer navigation package.

Prerequisites

The AWS DeepRacer device comes with all the prerequisite packages and libraries installed to run the deepracer_navigation_pkg. For more information about the preinstalled set of packages and libraries on the AWS DeepRacer and about installing the required build systems, see Getting started with AWS DeepRacer OpenSource.

The deepracer_navigation_pkg specifically depends on the following ROS 2 packages as build and run dependencies:

• deepracer_interfaces_pkg: This package contains the custom message and service type definitions used across the AWS DeepRacer core application.

Downloading and building

Open a terminal on the AWS DeepRacer device and run the following commands as the root user.

1. Switch to the root user before you source the ROS 2 installation:

    sudo su
   

2. Source the ROS 2 Foxy setup bash script:

    source /opt/ros/foxy/setup.bash 
   

3. Create a workspace directory for the package:

    mkdir -p ~/deepracer_ws
    cd ~/deepracer_ws
   

4. Clone the deepracer_navigation_pkg on the AWS DeepRacer device:

    git clone https://github.com/aws-deepracer/aws-deepracer-navigation-pkg.git
   

5. Fetch unreleased dependencies:

    cd ~/deepracer_ws/aws-deepracer-navigation-pkg
    rosws update
   

6. Resolve the deepracer_navigation_pkg dependencies:

    cd ~/deepracer_ws/aws-deepracer-navigation-pkg && rosdep install -i --from-path . --rosdistro foxy -y
   

7. Build the deepracer_navigation_pkg and deepracer_interfaces_pkg:

    cd ~/deepracer_ws/aws-deepracer-navigation-pkg && colcon build --packages-select deepracer_navigation_pkg deepracer_interfaces_pkg
   

Usage

Although the deepracer_navigation_node is built to work with the AWS DeepRacer application, you can run it independently for development, testing, and debugging purposes.

Run the node

To launch the built deepracer_navigation_node as the root user on the AWS DeepRacer device, open another terminal on the AWS DeepRacer device and run the following commands as the root user.

1. Switch to the root user before you source the ROS 2 installation:

    sudo su
   

2. Source the ROS 2 Foxy setup bash script:

    source /opt/ros/foxy/setup.bash 
   

3. Source the setup script for the installed packages:

    source ~/deepracer_ws/aws-deepracer-navigation-pkg/install/setup.bash 
   

4. Launch the deepracer_navigation_node using the launch script:

    ros2 launch deepracer_navigation_pkg deepracer_navigation_pkg_launch.py
   

Launch files

The deepracer_navigation_pkg_launch.py, included in this package, provides an example demonstrating how to launch the deepracer_navigation_node.

from launch import LaunchDescription
from launch_ros.actions import Node

def generate_launch_description():
    return LaunchDescription([
        Node(
            package='deepracer_navigation_pkg',
            namespace='deepracer_navigation_pkg',
            executable='deepracer_navigation_node',
            name='deepracer_navigation_node'
        )
    ])

Node details

deepracer_navigation_node

Subscribed topics

Topic name	Message type	Description
/inference_pkg/rl_results	InferResultsArray	This message holds the reinforcement learning inference results for the state input passed through the current model that is selected in the device console.

Published topics

Topic name	Message type	Description
/deepracer_navigation_pkg/auto_drive	ServoCtrlMsg	Publish a message with steering angle and throttle data sent to the servo package to move the car.

Services

Service name	Service type	Description
action_space_service	LoadModelSrv	A service that is called when a new model is loaded and helps set the action space to be considered while mapping the inference results.
throttle_service	NavThrottleSrv	A service that is called to dynamically set the scale value to multiply to the throttle in autonomous mode for each action.

Resources

• Getting started with AWS DeepRacer OpenSource