BrickSim: A Physics-Based Simulator for Manipulating Interlocking Brick Assemblies

TL;DR

BrickSim is a real-time, physics-based simulator specifically designed for interlocking brick assemblies, accurately modeling snap-fit mechanics and structural behavior to advance robotic manipulation research.

Contribution

It introduces a novel force-based mechanics model for snap-fit connections and a hybrid simulation architecture enabling high-fidelity, real-time simulation of brick assembly processes.

Findings

Achieves 100% accuracy in static stability prediction on real-world data

Faithfully reproduces structural collapse and breakage locations in dynamic tests

Supports seamless integration with robotic systems and existing simulation pipelines

Abstract

Interlocking brick assemblies provide a standardized yet challenging testbed for contact-rich and long-horizon robotic manipulation, but existing rigid-body simulators do not faithfully capture snap-fit mechanics. We present BrickSim, the first real-time physics-based simulator for interlocking brick assemblies. BrickSim introduces a compact force-based mechanics model for snap-fit connections and solves the resulting internal force distribution using a structured convex quadratic program. Combined with a hybrid architecture that delegates rigid-body dynamics to the underlying physics engine while handling snap-fit mechanics separately, BrickSim enables real-time, high-fidelity simulation of assembly, disassembly, and structural collapse. On 150 real-world assemblies, BrickSim achieves 100% accuracy in static stability prediction with an average solve time of 5 ms. In dynamic drop tests, it also faithfully reproduces real-world structural collapse, precisely mirroring both the occurrence of breakage and the specific breakage locations. Built on Isaac Sim, BrickSim further supports seamless integration with a wide variety of robots and existing pipelines. We demonstrate robotic construction of brick assemblies using BrickSim, highlighting its potential as a foundation for research in dexterous, long-horizon robotic manipulation. BrickSim is open-source, and the code is available at https://github.com/intelligent-control-lab/BrickSim.