Does a stiffer friction cone make the held-bar result in robofab-liftload threshold-free?
research/robofab-barimpratio
Does a stiffer friction cone make the held-bar result threshold-free? Creep falls about as 1/impratio (3.66 to 0.004 deg/s); from impratio 10 the 1 and 5 degree forces agree within 26%, and MuJoCo needs 0.67 to 1.17 times the old torque bracket's lower bound (stylised).
What it found
A follow-up to robofab-sliprate, which traced the bar’s creep to MuJoCo’s contact settings. Raising the impratio option from 1 to 1000 cuts the creep of a 10×10×40 mm bar held at one end from 3.66 to 0.004 deg/s, roughly as 1/impratio. From impratio 10 the minimum holding forces for 1° and 5° tolerances agree within 26% in all 12 cases, so the answer no longer depends on the threshold. The simulated force is below the uniform-pressure torque bracket in 10 of 12 cases (0.67–1.17× its lower bound) and 1.15–1.67× a point-contact bound built on the five contacts per pad MuJoCo reports. One engine, one bar section, no torsional friction. Stylised and preliminary.
A figure from its own output
Paper, code and results
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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.