Deformable PET bottle sim with GPT-6 Astra: plasticity kernel and 32k-particle water
rocky_mountain12 · reddit · 2026-09-30
A Redditor demonstrates GPT-6 Astra squeezing a water bottle in RobotGym.io with accurate physics, useful for LLM-based robotics training in simulation.
- Bottle modeled as a 0.3mm PET shell with real values: 3 GPa stiffness, 55 MPa yield strength
- Simulated on GPU with Newton's VBD solver, self-contact enabled so the wall buckles like plastic instead of squishing like rubber
- Key challenge was persistent dents: a custom plasticity kernel makes creases past PET's yield point the new resting shape — the bottle stays crushed
- Water simulated as 32,000 particles in a custom position-based fluid solver that preserves volume, forcing water up and out of the neck
- Path-traced in a full apartment scene with clear PET, refracting water, and a real Franka arm
Related event: GPT-6 Astra Simulates Physically Accurate PET Bottle Squeezing(2 posts)→
More from Embodied
- Running ML Models on a Smart RC Controller — braedenhall_ · 2026-09-30
- First Ride in Waymo's New Ojai: Roomier but Slower and Pricier Than Lyft — binarybits · 2026-09-30
- Claude as a Robot Integrator: Choreographed Data Collection for Vision-Guided Insertion — ihorbeaver · 2026-09-30
- MIRA 2.0 UI moves text to top of display to keep eye contact — AnhPhuNguyen1 · 2026-09-30
- MIRA 2.0 launches with all-day memory, voice agents and Claude Code integration — AnhPhuNguyen1 · 2026-09-30
- Deformable physics sim with GPT-6 Astra: PET bottle crushing with plasticity and fluids — rocky_mountain12 · 2026-09-30