URC Intelligent Systems 2024

This repository contains the intelligent systems division's modules and sensor logic for SJSU Robotics' latest Mars Rover. It is based on ROS Humble, although it can be (probably) used with ROS Jazzy as well.

Architecture

• Sensors publish their raw data to their respective topics
• Map nodes process that data and publish a 2d array with obstacles and free spaces to /map
• Control nodes subscribe to /map and any raw data that they need to in order to publish goals to /goal
• Pathfinder nodes subscribe to /map and /goal and push command requests to the CAN bus

Getting Started

Placing the Repository

This repository is already a ROS workspace with a complete src directory. This means several things:

• You do not need to clone this repository into an existing ROS workspace.
• All ROS commands should be executed from the root of this repository.

Dependencies

To get started, make sure you have ROS Humble installed. You can check out the install instructions available on the ROS website. You will also need colcon, which can be installed according to this ROS tutorial. Finally, make sure that you install all the repository-specific dependencies by running

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

More details about rosdep can be found on the ROS rosdep tutorial.

Repository Structure

The repository is already a ROS workspace. As such, it contains a src directory with individual packages. Each individual package has the following subdirectories:

• launch (optional) - this directory contains scripts that can be run using ros2 launch (package name) (script name). This is only present in the urc_intelsys_2024 package.
• msg (optional) - this directory contains message definitions that allow us to pass structured data over topics. This is only present in the urc_intelsys_2024_msg package.
• test - this directory contains tests that can be run using colcon test
• resource - this directory should only contain the empty file (package name). It is used purely for ROS 2's internals and shouldn't be altered.
• (package name) - this directory is where the code for the package goes.

Workflow

Building

From the root of this repository, you can use colcon to build the ROS packages. For Python packages, this simply bundles all the files together and puts them into the install directory. For C++ packages, this actually compiles and links any executables in the package.

Building all Packages

To build all packages, run

colcon build

Building Selected Packages

To build only certain packages, you can use the --packages-select argument followed by the packages you'd like to build.

colcon build --packages-select compass gps

Installing

Once built, there should be an install directory present in the root of this repository. To install the built packages, simply run

source install/setup.sh

If you have Zshell, you'll run

source install/setup.zsh

Running

After installing, scripts and launch files can be run with ros2 run and ros2 launch, respectively.

Scripts

Scripts are the entry points into our applications. They are often single nodes, but sometimes are more than one node. We define the scripts for a package in src/(package name)/setup.py, and then we can run those scripts with the following command:

ros2 run (package name) (entry_point_name)

For example, to run the GPS publisher, you can run

ros2 run gps gps

To pass arguments to a node, you can specify the --ros-args -p flag followed by all the arguments that you want to pass, in the format argument_name:=argument_value.

Launch Files

Launch files (defined in src/urc_intelsys_2024/launch/*.py) act as a way to launch multiple nodes at the same time. To run a launchfile, run the following command:

ros2 launch urc_intelsys_2024 (launch_file_name).py

For example, to run all sensors, you can run

ros2 launch urc_intelsys_2024 sensor_launch.py

To pass arguments (for example, to specify that all sensors should be fake), you can specify (argument_name):=(value). For example:

ros2 launch urc_intelsys_2024 sensor_launch.py compass_type:=fake gps_type:=fake

Alternatively, you can also edit the values in the config file, found in sr/urc_intelsys_2024/config/config.yaml and re-build the urc_intelsys_2024 package.

To learn more about launchfiles, see the ROS documentation.

Contributing

To add a new Python package, you can run

ros2 pkg create --build-type ament_python (package_name)

Then, to add an executable node, edit the file setup.py within the package. Edit the entry_points variable as follows:

setup(
    ...
    # edit entry_points:
    entry_points={
        "console_scripts": [
            "node_name = package.file:function",
            ...  # add any other nodes you have
        ]
    }
)

To learn more about this, check out the ROS2 documentation for creating packages.

Before pushing your code, please run python3 -m black ./src to format your code. Otherwise, your code will fail formatting checks.