This repository contains symbolic derivations of the kinematics and dynamics of various soft robots using Sympy. The symbolic expressions are then implemented in JAX and can be used for fast, parallelizable, and differentiable simulations. So far, we have focused on planar settings and implemented the following soft robots:

• N-link pendulum
• Planar Piecewise Constant Strain (PCS) continuum soft robot
• Planar Handed Shearing Auxetics (HSA) robot

We are happy to receive contributions for other soft robots and/or other settings (e.g., 3D).

This simulator is part of the publication An Experimental Study of Model-based Control for Planar Handed Shearing Auxetics Robots presented at the 18th International Symposium on Experimental Robotics. You can find the publication online in the Springer Proceedings on Advanced Robotics (SPAR).

Please use the following citation if you use our software in your (scientific) work:

@inproceedings{stolzle2023experimental,
  title={An Experimental Study of Model-based Control for Planar Handed Shearing Auxetics Robots},
  author={St{\"o}lzle, Maximilian and Rus, Daniela and Della Santina, Cosimo},
  booktitle={Experimental Robotics: The 18th International Symposium},
  year={2023},
  organization={Springer}
}

The plugin can be installed from PyPI:

pip install jsrm

or locally from the source code:

pip install .

If you want to run the examples, you will also need to install the following dependencies:

pip install ".[examples]"

Always first source all necessary environment variables when opening a new terminal:

source 01-configure-env-vars.sh

Then, we can symbolically derive the pendulum kinematics and dynamics:

python examples/derive_pendulum.py

Finally, we can simulate the pendulum

python examples/simulate_pendulum.py

You might also be interested in the following repositories:

• The jax-spcs-kinematics repository contains an implementation of the Selective Piecewise Constant Strain (SPCS) kinematics in JAX. We have shown in our paper that this kinematic model is suitable for representing the shape of HSA rods.
• The HSA-PyElastica repository contains a plugin for PyElastica for the simulation of HSA robots.
• The hsa-planar-control repository contains JAX and ROS2 implementations of model-based control algorithms for planar HSA robots.