How much of the gap between “the twin passes” and “it fails for real” does each twin fidelity close?
research/robofab-program
Session-written pick-and-place programs checked in a kinematic SCARA twin at three fidelities against a held-out reference: of 69 reference-failing injected-bug mutants the levels reject 38, 46 and 60 with no false alarms; misses are unmodelled effects (stylised).
What it found
A kinematic SCARA pick-and-place twin at three checking levels (geometry; plus joint, payload and deadline limits; plus stochastic grasp error, grip build-up and slip) against a held-out reference twin. Of 162 injected-bug mutants of three programs, 69 fail the reference; the levels reject 38, 46 and 60 of them, with no false alarms. The misses are effects the checker does not model, so the rates reflect how the reference was built. Four programs written by the building session: three failed the reference as drafted, and one failure (payload at long reach) was invisible to all three levels. Stylised, kinematic only, no language-model API called.
Paper, code and results
More in Robot manufacturing loops
- Which resource limits a small robot-printer-inspection cell, and does the busiest one tell you what to upgrade?Discrete-event twin of an arm, printers and an inspection station: printers have the highest utilisation at every size, yet at 6 printers an extra arm saves 10.9 min vs 2.3 for an extra inspection station; dispatch rules trade makespan for flow time; a mean-value twin is optimistic. Stylised, illustrative parameters.
- Where is the bottleneck of an arm, printer and inspection cell?Discrete-event twin of an arm, 3D printers and an inspection station: a utilisation bound names the bottleneck (printers to 10, the arm from 12, ~12.7 good parts/h) and the simulation sits 10–11% below it near the switch; a 25% faster arm lifts 11.34 to 12.68 parts/h at 12 printers, a second inspector nothing (stylised).
- Does exact queueing analysis predict a robot-printer cell's throughput better than a utilisation bound?Exact mean value analysis of the arm, printers and inspection network against a discrete-event twin: a few per cent off for exponential times, up to 11% low for less variable ones, better than the utilisation bound in most real-semantics rows, and it overshoots saturation at high work in process. Stylised.
- Where does exact queueing analysis of a robot-printer cell stop working?Coefficient-of-variation sweep and a measured printer stall share for the arm-printer-inspection queueing model: MVA's error crosses zero near cv 1 while the utilisation bound stays high, and held-printer capacity times (1 − stall) reproduces the saturated rate at 4 and 8 printers. Stylised.
- Is a print-failure camera worth it in a robot-arm 3D-printer cell?Is a print-failure camera worth it in a robot-arm printer cell? Blind printing against abort-on-failure: +6 to 10% good parts per hour at 2 to 10 printers, none once the arm limits the cell; break-even false-stop rate. Stylised.
- Where should a print-failure detector's alarm threshold go in a robot-arm 3D-printer cell?Where should a print-failure detector's alarm threshold go in a robot-arm printer cell? A look every 2 min makes a z = 2 threshold 19 to 23% worse than blind printing; the best z is 3 to 3.5, worth +6% (d' = 2) to +11% (d' = 4). Stylised.
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Other research topics
Proper scoring & elicitation28Effort & peer prediction9Verification games & slashing19Detection & tolerances14Markets as routers13Prediction-market design9Paying contributors8Decentralised training systems23Digital twins & sim-to-real164LLM chip design loops40Robot manufacturing loops53Ambient AI assistant46Self-replicating manufacturing34Simulation-first design64Engineered clothing45Task-specific AI accelerators40Algorithmic chip-design loops42Open-source purpose-built robots44The software-engineering loop43Adversarial human imitation41Open-source residential construction41Autonomous multi-angle capture34Sensing, imaging and 3D31Energy supply and dense energy storage39Robot societies among people31Agentic co-design of low-cost robots27Laundry-hanging robots25Machine learning on qualitative data23Robots on the building site27Civilizations & group psychology1History & human sciences1
Produced with AI assistance (Claude). Results are from the code in this repository and are simulated or stylised unless the abstract says otherwise; nothing here implies affiliation with or endorsement by any lab, researcher or company cited. MIT licensed.