# simbody/simbody

High-performance C++ multibody dynamics/physics library for simulating articulated biomechanical and mechanical systems like vehicles, robots, and the human skeleton.

Repository: https://github.com/simbody/simbody
Canonical: https://ross.abutalabs.com/products/simbody
Homepage: https://simtk.org/home/simbody
Language: C++
License: Apache-2.0
License Family: permissive
Topics: multibody-dynamics, physics-engine, physics-simulation, robotics, biomechanics
Last push: 2026-08-25T16:50:51+00:00

## Health v2 (maintenance only)
Score: 67/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 8, longevity 100
- inputs: {"age_days": 4766, "days_push": 8, "days_rel": 473, "gap_med": null, "n_releases_24m": 1}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2547, forks 496 (observed 2026-08-28T04:07:00.335502+00:00)

## What it is
Simbody is a high-performance open-source C++ multibody dynamics library for science- and engineering-quality simulation of articulated mechanisms such as skeletons, robots, vehicles, and machines. It uses a Featherstone-style O(n) formulation in generalized coordinates and serves as an API for building domain-specific applications like OpenSim and Gazebo.

## Use cases
- simulate articulated rigid body mechanisms with joints and constraints
- simulate human or animal skeletal biomechanics
- physics simulation for robotics applications
- model vehicle or machine dynamics in C++
- internal-coordinate modeling of molecules
- real-time interactive biosimulation or animation

## When to choose
- you need accuracy-controlled, engineering-quality multibody dynamics rather than game-grade approximations
- you are building a C++ application needing O(n) articulated-body dynamics
- you work in biomechanics, robotics, or molecular modeling and want a proven engine used by OpenSim and Gazebo

## When to avoid
- you want a standalone physics application or GUI rather than a C++ library
- you need soft-body, fluid, or particle simulation
- you prefer a high-level scripting interface like Python or a game-engine plugin out of the box

## Facets
- artifact type: library
- maturity: stable
- function: simulation, graphics, math
- domain: robotics, simulation, healthcare
- platform: cpp, cross-platform, windows
- tags: multibody-dynamics, physics-engine, featherstone, biomechanics, rigid-body-dynamics, articulated-bodies, c-plus-plus-api, game-development, algorithms, linux, macos

## Member repositories
- simbody/simbody (main) score 67

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:07:00.335502+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T02:24:35.076158+00:00, confidence not recorded.
  - readme: https://github.com/simbody/simbody (fetched 2026-08-28T04:07:00.335502+00:00, sha d5697e0783b8)
  - homepage: https://simtk.org/home/simbody (fetched 2026-08-29T10:08:20.570791+00:00, sha b46753af53a6)
  - site_page: https://simtk.org/aboutCommunities.php (fetched 2026-08-29T10:08:20.579903+00:00, sha 6cc54b8a1d61)
  - site_page: https://simtk.org/features.php (fetched 2026-08-29T10:08:20.581647+00:00, sha db7714e1f677)
  - site_page: https://simtk.org/faq.php (fetched 2026-08-29T10:08:20.583466+00:00, sha 67b871afbd9f)
  - site_page: https://simtk.org/tracker?atid=232&group_id=47&func=browse (fetched 2026-08-29T10:08:20.585279+00:00, sha ba3b578da14d)
  - site_page: https://simtk.org/whatIsSimtk.php (fetched 2026-08-29T10:08:20.586936+00:00, sha 209c14d9e572)
- Data as of 2026-08-30T08:39:29.467469+00:00.