Google Research

Single-Level Differentiable Contact Simulation

IEEE RAL (2023)


We present a differentiable formulation of rigid-body contact dynamics for objects and robots represented as compositions of convex primitives. Existing optimization-based approaches simulating contact between convex primitives rely on a bilevel formulation that separates collision detection and contact simulation. These approaches are unreliable in realistic contact simulation scenarios because isolating the collision detection problem introduces contact location non-uniqueness. Our approach combines contact simulation and collision detection into a unified single-level optimization problem. This disambiguates the collision detection problem in a physics-informed manner. Compared to previous differentiable simulation approaches, our formulation features improved simulation robustness and computational complexity improved by more than an order of magnitude. We provide a numerically efficient implementation of our formulation in the Julia language called \href{}{DojoLight.jl}.

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