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Fluidic Object-Oriented Network Simulator

Project description


Fluidic Object-oriented Network SIMulator

An object-oriented Python 3 library designed for simulating pneumatic and hydraulic systems in soft robots.

This project is available under the GNU Affero General Public License v3.0 (agpl-3.0) license.


The pre-packaged release version can be installed using pip install fonsim. See the PyPi page for more information.

Currently, FONSIM resides in an early alpha stage. Not all features work yet and you will encounter bugs. We look forward to your feedback. Thank you for your understanding.


  • Powerful and fast simulation backend
    • Newton-Raphson method for handling nonlinear equations
    • Backward Euler time discretization for stability
  • Implicit component equations
  • Fluid class
    • custom fluids, e.g. non-Newtonian
    • fallback functionality
  • Toolset focused on soft robotics (SoRo) research
    • read and process pv-curves
  • Standard library of fluidic components
    • Tubes, nodes, pressure sources, volume sources, containers, one-way valves, ...
  • Flow calculations
    • Compressible flow approximations
    • Laminar and turbulent flow based on Reynold number
    • Major and minor losses (Darcy, Haaland, K-factor etc.)
  • Preconfigured custom plot methods
  • Export data for further processing as JSON file
  • Cross platform

How to get started

The examples directory contains a set of examples showcasing various features of the simulator. We suggest to start with running the examples. Furthermore you may want to consult the documentation on Note: documentation is a WIP, not yet available. The same documentation is also available by the Python help function. If something is not fully clear, please let us know.


  • matplotlib
  • numpy
  • scipy

Project development, contribution


Are you interested in contributing to this project? Please get in touch so we can coordinate the development!


The FONS project branching is based on the Driessen or git-flow model. Put simply, the master branch is reserved for production-ready code. All software in master should be stable and usable. The dev branch contains the latest developed features, yet as a result the software is not as stable. The actual features (and improvements in general) are developed in the feature branches, for example feature-plotting.

To get this repo locally

  1. Clone the repo (notice the $ - this means to do it in a terminal/console). The directory with the project will be located in the current working directory of the terminal.
    $ git clone
  2. Go in the created directory (note: one can use TAB for autocompletion)
    $ cd fonsim

Create a local install

A local install allows to try out the library locally. This can be useful during development. First, rename the project root directory to fonsim (default name after Git clone: fons). Second, run in the project root directory:

$ python -m pip install -e .

This installs the FONS package such that it is accessible like all other Python packages, e.g. using import fonsim. The -e option denotes that it uses a symbolic link: code changes in the project directory (including branch switching) take effect at the first following import. No re-installation is required.

Note: python should refer to Python 3. You may have to write python3 to avoid using Python 2.

Note: there appear to be problems with this method on some Windows machines.

Note: if you want to install several versions of the same package on your system, for example a stable version from PyPi and a development version from a local install, you may want to use a Python virtual environment.

Development tools

A git repository history visualizer tool like gitg can be helpful in developing this software. It shows the relations between version branches visually, lists all commits and allows to see the exact changes were made in a particular commit. In addition, it can show uncommitted changes.

Gitlab provides similar tools as a web version like the GitLab graph.

Style guide


Arne Baeyens
Bert Van Raemdonck

Problems, questions, suggestions

If you have a question the FAQ section does not answer sufficiently, or you think you have encountered a bug, you can reach out by creating an issue on the GitLab Issues page. The issues page is also the proper place to post suggestions and feedback.



Project details

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