Reproducibility Package for the Paper "Shielded Reinforcement Learning for Hybrid Systems"

This repsitory contains supplementary code for the paper Shielded Reinforcement Learning for Hybrid Systems by Asger Horn Brorholt, Peter Gjøl Jensen, Kim Guldstrand Larsen, Florian Lorber and Christian Schilling. (doi, arxiv) This paper was published in Bridging the Gap Between AI and Reality - 1st International Conference and presented at the AISoLA conference in 2023.

Sample results are available as a Release. To cite the work, you can use:

@inproceedings{BrorholtJLLS24,
  author       = {Asger Horn Brorholt and
                  Peter Gj{\o}l Jensen and
                  Kim Guldstrand Larsen and
                  Florian Lorber and
                  Christian Schilling},
  title        = {Shielded reinforcement learning for hybrid systems},
  booktitle    = {{(A)ISoLA}},
  series       = {LNCS},
  volume       = {14380},
  publisher    = {Springer},
  year         = {2024},
  url          = {https://doi.org/10.1007/978-3-031-46002-9\_3},
  doi          = {10.1007/978-3-031-46002-9\_3}
}

The longest-running experiment is around 80 hours. No graphics acceleration is required.

Installation Instructions

This package was developed and tested on Ubuntu 22.04.1 LTS. These instructions apply to that operating system.

Packages

Make sure you have the following packages installed on your system:

sudo apt install gcc wget python3.10 default-jre

Install julia 1.8.2

cd ~/Downloads
wget https://julialang-s3.julialang.org/bin/linux/x64/1.8/julia-1.8.2-linux-x86_64.tar.gz
tar zxvf julia-1.8.2-linux-x86_64.tar.gz
mv julia-1.8.2/ ~/julia-1.8.2
sudo ln -s ~/julia-1.8.2/bin/julia /usr/local/bin/julia

Download dependencies for this repository. Note that the ] key activates the package manager interface.

cd /path/to/this/repository
julia --project=.
] instantiate

Install UPPAAL STRATEGO 10 and 11, and Activate License

Stratego 10 has a bug related to the Cruise-control example, while the final release of Stratego 11 has a bug that prevents running models with .q files in CLI. For all other versions, stratego 10 is fine. Versions beyond Stratego 11 may also work, when the issue is fixed.

If the following wget request is denied, please visit uppaal.org and follow download instructions.

mkdir ~/opt
cd ~/opt
wget https://download.uppaal.org/uppaal-4.1.20-stratego/stratego-10/uppaal-4.1.20-stratego-10-linux64.zip
unzip uppaal-4.1.20-stratego-10-linux64.zip
wget https://people.cs.aau.dk/~marius/beta/old/uppaal-4.1.20-stratego-11-rc1-linux64.zip
unzip uppaal-4.1.20-stratego-11-rc1-linux64.zip

Retrieve a license from https://uppaal.veriaal.dk/academic.html or alternatively visit uppaal.org for more info. Once you have your license, activate it by running

~/opt/uppaal-4.1.20-stratego-10-linux64/bin/verifyta.sh --key YOUR-LICENSE-KEY
~/opt/uppaal-4.1.20-stratego-11-linux64/bin/verifyta.sh --key YOUR-LICENSE-KEY

How to run

Create figures by running their corresponding experiment. Shown here for fig-BarbaricMethodAccuracy

cd path/to/ReproducibilityPackage
julia  "fig-BarbaricMethodAccuracy/Run Experiment.jl" --results-dir ~/Results

Glossary of Code Abbreviations

I am a big fan of not having to remember how a variable has been abbreviated, but sometimes I have to make an exception.

• shield The term "shield" is used interchangably with "nondeterministic safety strategy". Shields should have type Grid.
• grid refers to a partitioning of the state space, plus an integer value associated with each partition. This integer is used in various ways to represent the set of allowable actions in that partition. Thus, a grid could have also been called a safety strategy.
• G is the granularity of the grid, currently 𝛾 in the paper.
• Ivl, Ivu, Ixl, Ixu ... Are used to represeent upper and lower bounds for a partition. The I is short for interval, followed by the variable, and then either an l or an u depending on whether it is the lower or upper bound.
• iv, ix ... are used to represent indices into the matrix that is the underlying data structure of the grid. For example if a grid has v_min=-8, and G=1 then iv=9 would represent the square where Ivl = iv*G + (v_min/G) = 9 - 8 = 1
• R Reachability funciton. A function that given an initial square and an action, returns all squares reachable from the latter by that action. Similar to the reachability arrow, -> in the article.
• R̂ Approximated reachability function. Usually the barbaric reachability function. Similar to ->_app in the article.
• grid_points Support points in the paper. A cloud of evenly spaced points inside of a square, used to approximate reachability.
• spa Samples Per Axis, in the context of grid-points. Called n in the paper.
• dir This is an easy one. Short for directory. The (relative) path of a file or a folder.
• t Time.
• t_hit Period between actions for the bouncing ball. t_act for cruise control.
• v, p Velocity, Position.
• death Safety violation. Term borrowed from video games.
• runs Training runs. These are called episodes in the paper.