SMACC2

SMACC2 is an event-driven, asynchronous, behavioral state machine library for real-time ROS 2 (Robotic Operating System) applications written in C++, designed to allow programmers to build robot control applications for multicomponent robots, in an intuitive and systematic manner.

Repository Status, Packages and Documentation

ROS 2 Distro	Branch	Build status	Documentation	Released packages
Foxy	foxy		Generated Doc	SMACC2
Humble	humble		Generated Doc	SMACC2
Jazzy	jazzy		Generated Doc	SMACC2

NOTE: There are three build stages checking current and future compatibility of the package.

1. Binary builds - against released packages (main and testing) in ROS distributions. Shows that direct local build is possible.

   Uses repos file: src/SMACC2/.github/SMACC2-not-released.<ros-distro>.repos

2. Semi-binary builds - against released core ROS packages (main and testing), but the immediate dependencies are pulled from source. Shows that local build with dependencies is possible and if fails there we can expect that after the next package sync we will not be able to build.

   Uses repos file: src/SMACC2/.github/SMACC2.repos

3. Source build - also core ROS packages are build from source. It shows potential issues in the mid future.

Getting started - ROS Jazzy

1. Install ROS 2 Jazzy.

2. Make sure that colcon, its extensions, vcs, and development tools are installed:

   sudo apt install python3-colcon-common-extensions python3-vcstool clang-format pre-commit
   

1. Create a new ROS 2 workspace if necessary:

   export COLCON_WS=~/workspace/jazzy_ws
   mkdir -p $COLCON_WS/src
   

1. Or just navigate to your workspace source folder:

   cd ~/workspace/jazzy_ws/src
   

1. Clone the repo:

   git clone https://github.com/robosoft-ai/SMACC2.git
   

1. Checkout the Jazzy branch:

   cd ~/workspace/jazzy_ws/src/SMACC2
   git checkout jazzy
   

1. Navigate to the workspace:

   cd ~/workspace/jazzy_ws
   

1. Update System:

   sudo apt update
   sudo apt upgrade
   

1. Source the workspace:

   source /opt/ros/jazzy/setup.bash
   

1. Update dependencies:

   rosdep update
   

1. Pull relevant packages and install dependencies:

   vcs import src --skip-existing --input src/SMACC2/.github/SMACC2.jazzy.repos
   rosdep install --ignore-src --from-paths src -y -r
   

1. Compile:

   colcon build --cmake-args -DCMAKE_BUILD_TYPE=Release
   

Features

• Powered by ROS 2: SMACC2 has been developed specifically to work with ROS 2. It supports ROS 2 topics, services and actions, right out of the box.
• Written in C++: Until now, ROS 2 has lacked a library to develop task-level behavioral state machines in C++. Although libraries have been developed in scripting languages such as python, these are unsuitable for real-world industrial environments where real-time requirements are demanded.
• Orthogonals: Originally conceived by David Harel in 1987, orthogonality is absolutely crucial to developing state machines for complex robotic systems. This is because complex robots are always a collection of hardware devices which require communication protocols, start-up determinism, etc. With orthogonals, it is an intuitive and relatively straight forward exercise (at least conceptually;) to code a state machine for a robot comprising a mobile base, a robotic arm, a gripper, two lidar sensors, a gps transceiver and an imu, for instance.
• Static State Machine Checking: One of the features that SMACC2 inherits from Boost Statechart is that you get compile time validation checking. This benefits developers in that the amount of runtime testing necessary to ship quality software that is both stable and safe is dramatically reduced. Our philosophy is “Wherever possible, let the compiler do it”.
• State Machine Reference Library: With a constantly growing library of out-of-the-box reference state machines, (found in the folder sm_reference_library) guaranteed to compile and run, you can jumpstart your development efforts by choosing a reference machine that is closest to your needs, and then customize and extend to meet the specific requirements of your robotic application. All the while knowing that the library supports advanced functionalities that are practically universal among actual working robots.
• SMACC2 Client Library: SMACC2 also features a constantly growing library of clients that support ROS 2 Action Servers, Service Servers and other nodes right out-of-the box. The clients within the SMACC2 Client library have been built utilizing a component based architecture that allows for developer to build powerful clients of their own. Current clients of note include MoveBaseZ, a full featured Action Client built to integrate with Nav2, the cl_ros2_timer, the multi_role_sensor_client, and a cl_keyboard used extensively for state machine drafting & debugging.
• Extensive Documentation: Although many ROS users are familiar with doxygen, our development team has spent a lot of time researching the more advanced features of doxygen such as uml style class diagrams and call graphs, and we’ve used them to document the SMACC2 library. Have a look to our doxygen sites and we think you’ll be blown away at what Doxygen looks like when it’s done right and it becomes a powerful tool to research a codebase.
• SMACC2 Runtime Analyzer: The SMACC2 library works out of the box with the SMACC2 RTA. This allows developers to visualize and runtime debug the state machines they are working on. The SMACC2 RTA is closed source, but is free for individual and academic use. It can be found here.

Repository Structure

• smacc2 - core library of SMACC2.
• smacc2_client_library - client libraries for SMACC2, e.g., Navigation2 (nav2z_client), MoveIt2 (moveit2z_client).
• smacc2_event_generators - …
• smacc2_msgs - ROS 2 messages for SMACC2 framework.
• smacc2_sm_reference_library - libraries with reference implementations of state-machines used for demonstration and testing of functionalities.
• ↓smacc2_state_reactor_library - …
• smacc2_performance_tools - …

SMACC2 applications

From it’s inception, SMACC2 was written to support the programming of multi-component, complex robots. If your project involves small, solar-powered insect robots, that simply navigate towards a light source, then SMACC2 might not be the right choice for you. But if you are trying to program a robot with a mobile base, a robotic arm, a gripper, two lidar sensors, a gps transceiver and an imu, then you’ve come to the right place.

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Contributing Guidelines

Thank you for your interest in contributing to smacc2. Whether it’s a bug report, new feature, correction, or additional documentation, we greatly value feedback and contributions from our community.

Please read through this document before submitting any issues or pull requests to ensure we have all the necessary information to effectively respond to your bug report or contribution.

Reporting Bugs/Feature Requests

We welcome you to use the GitHub issue tracker to report bugs or suggest features.

When filing an issue, please check existing open, or recently closed, issues to make sure somebody else hasn’t already reported the issue. Please try to include as much information as you can. Details like these are incredibly useful:

• A reproducible test case or series of steps
• The version of our code being used
• Any modifications you’ve made relevant to the bug
• Anything unusual about your environment or deployment

Contributing via Pull Requests

Contributions via pull requests are much appreciated. Before sending us a pull request, please ensure that:

1. Limited scope. Your PR should do one thing or one set of things. Avoid adding “random fixes” to PRs. Put those on separate PRs.
2. Give your PR a descriptive title. Add a short summary, if required.
3. Make sure the pipeline is green.
4. Don’t be afraid to request reviews from maintainers.
5. New code = new tests. If you are adding new functionality, always make sure to add some tests exercising the code and serving as live documentation of your original intention.

To send us a pull request, please:

1. Fork the repository.
2. Modify the source; please focus on the specific change you are contributing. If you also reformat all the code, it will be hard for us to focus on your change.
3. Ensure local tests pass. (colcon test and pre-commit run -a (requires you to install pre-commit by sudo apt install pre-commit on Ubuntu 24.04+)
4. Commit to your fork using clear commit messages.
5. Send a pull request, answering any default questions in the pull request interface.
6. Pay attention to any automated CI failures reported in the pull request, and stay involved in the conversation.

GitHub provides additional documentation on forking a repository and creating a pull request.

Finding contributions to work on

Looking at the existing issues is a great way to find something to contribute on. As this project, by default, uses the default GitHub issue labels (enhancement/bug/duplicate/help wanted/invalid/question/wontfix), looking at any ‘help wanted’ issues is a great place to start.

Licensing

Any contribution that you make to this repository will be under the Apache 2 License, as dictated by that license:

5. Submission of Contributions. Unless You explicitly state otherwise,
   any Contribution intentionally submitted for inclusion in the Work
   by You to the Licensor shall be under the terms and conditions of
   this License, without any additional terms or conditions.
   Notwithstanding the above, nothing herein shall supersede or modify
   the terms of any separate license agreement you may have executed
   with Licensor regarding such Contributions.