Simulation

Contact Simulation

Contact simulation is the numerical modeling of forces and motion arising when rigid or deformable bodies touch, requiring collision detection, contact force resolution, and friction modeling, typically via linear complementarity formulations, penalty methods, or MuJoCo's smooth convex approximation. Accurate, stable, and fast contact resolution is the hardest part of robotics simulation, and discrepancies between simulated and real contact dynamics are a principal source of the sim-to-real gap.

Why it matters for physical AI

Policies for manipulation and locomotion are predominantly trained in simulation, so contact model fidelity and speed directly bound what skills can be learned and how well they transfer to hardware.