Simbody is useful for internal coordinate and coarse grained molecule modeling, large scale mechanical models like skeletons, and anything else that can be modeled as bodies interconnected by joints, acted upon by forces, and restricted by constraints.

This project is a SimTK toolset providing general multibody dynamics capability, that is, the ability to solve Newton's 2nd law F=ma in any set of generalized coordinates subject to arbitrary constraints. (That's Isaac himself in the oval.) Simbody is provided as an open source, object-oriented C++ API and delivers high-performance, accuracy-controlled science/engineering-quality results.

Simbody uses an advanced Featherstone-style formulation of rigid body mechanics to provide results in Order(n) time for any set of n generalized coordinates. This can be used for internal coordinate modeling of molecules, or for coarse-grained models based on larger chunks. It is also useful for large-scale mechanical models, such as neuromuscular models of human gait, robotics, avatars, and animation. Simbody can also be used in real time interactive applications for biosimulation as well as for virtual worlds and games.

This toolset was developed originally by Michael Sherman at the Simbios Center at Stanford, with major contributions from Peter Eastman and others. Simbody descends directly from the public domain NIH Internal Variable Dynamics Module (IVM) facility for molecular dynamics developed and kindly provided by Charles Schwieters. IVM is in turn based on the spatial operator algebra of Rodriguez and Jain from NASA's Jet Propulsion Laboratory (JPL), and Simbody has adopted that formulation.

SOURCE CODE: Simbody is distributed in source form. The source code is maintained at GitHub. You can get a zip of the latest stable release here, then build it on your Windows, Mac OSX, or Linux machine (you will need CMake and a compiler).

You can also clone the git repository and build the latest development version here; the repository URL is https://github.com/simbody/simbody.git. If you would like to contribute bug fixes, new code, documentation, examples, etc. to Simbody (and we hope you will!), please fork the repository on GitHub and send pull requests.

If you are new to git, you may want to start with GitHub's Bootcamp tutorial.


OpenSim gets high marks as a multibody system simulator

Aug 3, 2015

A recent study by Luca Tagliapietra and his University of Padua colleagues demonstrates that the OpenSim software (http://opensim.stanford.edu), which uses Simbody as its multibody dynamics engine, generates highly accurate simulations of mechanical systems. OpenSim was evaluated using the Multi-Body System (MBS) Benchmark, which consists of five systems ranging from a simple pendulum to an over-constrained system of five rods and six rotational joints (Bricard’s mechanism).

Simbody source moved to GitHub

Oct 9, 2013

To facilitate a more social style of shared code development, Simbody's source code is now being maintained on GitHub, at https://github.com/simbody.

Simbody joins the DARPA Robotics Challenge

Nov 28, 2012

DARPA granted a sole-source contract to the Open Source Robotics Foundation (http://osrfoundation.org) to build a shared simulator (Gazebo) for the DARPA Robotics Challenge.

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Molmodel: SimTK molecular modeling API