Articulated Rigid Body (ARB)

Compact C++ articulated rigid body simulation library implementing:

• Articulated-body algorithm (ABA) - $O(N_B)$ forward dynamics for kinematic trees,
• Composite Rigid-Body Algorithm (CRBA) - $O(N_B^2)$ joint-space inertia matrix $M(q)$ for kinematic trees.
• Recursive Newton-Euler algorithm (RNEA) - $O(N_B)$ inverse dynamics for kinematic trees,
• Spatial algebra implementation (header-only),
• End-to-end automatic differentiability using autodiff (header-only),
• Collision Resolution – spatial impulses, GJK/EPA, and 4-point persistent contact manifolds,
• Unified Robot Description Format (URDF) import and export.

End-to-end automatic differentiation enables derivatives to propagate through the physics pipeline supporting system identification, gradient based optimisation, and machine learning applications.

Minimal dependencies: STL, glm, (autodiff, openGJK, and libccd optional).

Visual Demos

Simulating a simple real-world robot - the UR5:

https://youtu.be/mSGq3sTns7I

**Rigid body…