crane-fmu 0.2.0

Basic crane simulation model including publication as FMU, for usage in the SEACo project.

Introduction

The package extends the component_model package to provide the means to construct cranes. The package can be used to define concrete cranes and simulate their usage, see tests/resources/mobile-crane.py as example.

Getting Started

A concrete crane model should consist of an extension of the Crane object,

• defining general model variables like name, author, version, etc.

• defining the anticipated set of booms

• if there is a wish to keep parameters configurable, these can be kept as parameters of the extended model.

• In a separate script, instantiate the concrete crane, test it and run Model.build(…) to make the FMU.

See the file tests/resources/mobile_crane.py and related test files as an example on how a concrete crane can be defined and used.

Installation

pip install crane-fmu

Usage Example

This is a simple mobile crane, like they are used on e.g. building sites with

• a short pedestal, which can be turn around,

• one boom with variable length and which can be lifted

• one rope, where loads can be attached.

from crane_fmu.crane import Crane

class MobileCrane(Crane):
    """Simple mobile crane for FMU testing purposes.
    The crane has a short pedestal, one variable-length stiff boom and a rope.
    The size and weight of the various parts can be configured.

    Args:
        name (str) : name of the crane type
        description (str) : short description
        author (str)
        version (str)
        pedestalMass (str) : mass of the pedestal - quantity and unit as string
        pedestalHeight (str) : height (fixed) of the pedestal, with units
        boomMass (str) : mass of the single boom, with units
        boomLength0 (str) : minimum length of the boom, with units
        boomLength1 (str) : maximum length of the boom, with units
    """

    def __init__(
        self,
        name: str = "mobile_crane",
        description: str = "Simple mobile crane (for FMU testing) with short pedestal, one variable-length elevation boom and a rope",
        author: str = "DNV, SEACo project",
        version: str = "0.2",
        pedestalMass: str = "10000.0 kg",
        pedestalHeight: str = "3.0 m",
        boomMass: str = "1000.0 kg",
        boomLength0: str = "8 m",
        boomLength1: str = "50 m",
        rope_mass_range: tuple = ("50kg", "2000 kg"),
        **kwargs,
    ):
        super().__init__(name=name, description=description, author=author, version=version, **kwargs)
        _ = self.add_boom(
            name="pedestal",
            description="The crane base, on one side fixed to the vessel and on the other side the first crane boom is fixed to it. The mass should include all additional items fixed to it, like the operator's cab",
            mass=pedestalMass,
            massCenter=(0.5, -1.0, 0.8),
            boom=(pedestalHeight, "0deg", "0deg"),
            boom_rng=(None, None, ("0deg", "360deg")),
        )
        _ = self.add_boom(
            name="boom",
            description="The boom. Can be lifted and length can change within the given range",
            mass=boomMass,
            massCenter=(0.5, 0, 0),
            boom=(boomLength0, "90deg", "0deg"),
            boom_rng=((boomLength0, boomLength1), (0, "90deg"), None),
        )
        _ = self.add_boom(
            name="rope",
            description="The rope fixed to the last boom. Flexible connection",
            mass="50.0 kg",  # so far basically the hook
            massCenter=0.95,
            mass_rng=rope_mass_range,
            boom=("1e-6 m", "180deg", "0 deg"),
            boom_rng=(
                ("1e-6 m", boomLength1),
                ("90deg", "270deg"),
                ("-180deg", "180deg"),
            ),
            damping=50.0,
            animationLW=2,
        )
        # make sure that _comSub is calculated for all booms:
        self.calc_statics_dynamics(None)

    def do_step(self, currentTime, stepSize):
        status = super().do_step(currentTime, stepSize)
        # print(f"Time {currentTime}, {self.rope_tip}")
        # print(f"MobileCrane.do_step. Status {status}")
        return status

Testing and usage of the MobileCrane.fmu is demonstrated as part of related test_*** files.

Development Setup

1. Install uv

This project uses uv as package manager.

If you haven’t already, install uv, preferably using it’s “Standalone installer” method:

..on Windows:

powershell -ExecutionPolicy ByPass -c "irm https://astral.sh/uv/install.ps1 | iex"

..on MacOS and Linux:

curl -LsSf https://astral.sh/uv/install.sh | sh

(see docs.astral.sh/uv for all / alternative installation methods.)

Once installed, you can update uv to its latest version, anytime, by running:

uv self update

2. Install Python

This project requires Python 3.11 or later.

If you don’t already have a compatible version installed on your machine, the probably most comfortable way to install Python is through uv:

uv python install

This will install the latest stable version of Python into the uv Python directory, i.e. as a uv-managed version of Python.

Alternatively, and if you want a standalone version of Python on your machine, you can install Python either via winget:

winget install --id Python.Python

or you can download and install Python from the python.org website.

3. Clone the repository

Clone the crane-fmu repository into your local development directory:

git clone https://github.com/dnv-opensource/crane-fmu path/to/your/dev/crane-fmu

Change into the project directory after cloning:

cd crane-fmu

4. Install dependencies

Run uv sync -U to create a virtual environment and install all project dependencies into it:

uv sync -U

Note: Using --no-dev will omit installing development dependencies.

Explanation: The -U option stands for --update. It forces uv to fetch and install the latest versions of all dependencies, ensuring that your environment is up-to-date.

Note: uv will create a new virtual environment called .venv in the project root directory when running uv sync -U the first time. Optionally, you can create your own virtual environment using e.g. uv venv, before running uv sync -U.

5. (Optional) Activate the virtual environment

When using uv, there is in almost all cases no longer a need to manually activate the virtual environment.

uv will find the .venv virtual environment in the working directory or any parent directory, and activate it on the fly whenever you run a command via uv inside your project folder structure:

uv run <command>

However, you still can manually activate the virtual environment if needed. When developing in an IDE, for instance, this can in some cases be necessary depending on your IDE settings. To manually activate the virtual environment, run one of the “known” legacy commands:

..on Windows:

.venv\Scripts\activate.bat

..on Linux:

source .venv/bin/activate

6. Install pre-commit hooks

The .pre-commit-config.yaml file in the project root directory contains a configuration for pre-commit hooks. To install the pre-commit hooks defined therein in your local git repository, run:

uv run pre-commit install

All pre-commit hooks configured in .pre-commit-config.yam will now run each time you commit changes.

pre-commit can also manually be invoked, at anytime, using:

uv run pre-commit run --all-files

To skip the pre-commit validation on commits (e.g. when intentionally committing broken code), run:

uv run git commit -m <MSG> --no-verify

To update the hooks configured in .pre-commit-config.yaml to their newest versions, run:

uv run pre-commit autoupdate

7. Test that the installation works

To test that the installation works, run pytest in the project root folder:

uv run pytest

Meta

Copyright (c) 2025 DNV AS. All rights reserved.

Siegfried Eisinger - @LinkedIn - [e-mail]

Jorge Luis Mendez - @LinkedIn - [e-mail]

Distributed under the MIT license. See LICENSE for more information.

https://github.com/dnv-opensource/crane-fmu

Contributing

Anybody in the FMU, OSPand SEACo community is especially welcome to contribute to this code, to make it better, and especially including other features from model assurance and from SEACo issues.

To contribute, follow these steps:

1. Fork it https://github.com/dnv-opensource/crane-fmu/fork/

2. Create an issue in your GitHub repo

3. Create your branch based on the issue number and type (git checkout -b issue-name)

4. Evaluate and stage the changes you want to commit (git add -i)

5. Commit your changes (git commit -am 'place a descriptive commit message here')

6. Push to the branch (git push origin issue-name)

7. Create a new Pull Request in GitHub

For your contribution, please make sure you follow the STYLEGUIDE before creating the Pull Request.