Spanish bartons

Only the input is driven; every other part of this model moves by physics (MuJoCo), and its ratios are measured. Run it live, change its parameters, or switch the friction off to see the output stop.

Modelled as

two ropes of links (friction on the sheaves): the standing rope, 60 hemp links, from an eye in the ceiling under C, over the fixed sheave A, to B's becket; the hauling rope, 26 links, from C's becket over B to the hand

Measured

load/hand 0.206 (1 cm of lift for 5 hauled), B/hand −0.408 (B sinks twice as fast), sheaves C −2.11, A 4.19, B 6.43 rad/m (strand speeds: −2.13, 4.26, 6.38), pull 32.3 N against (W_C − 2 W_B)/5 less the hand's weight 32.5 N, pen ≤ 0.04 mm

Notes

Only the hand is driven (a slide in a guide along the hauling part, 2 cm/s, at most 45 N). Shared plate 16–17. The load first settles 2.6 cm as the ropes take its weight, then rises. Negative control: both ropes' contact with the sheaves off → the load does not rise (0.000; it drops to its stop while the hand still hauls).

Film (MP4) · GIF · Still (PNG) · Spec (YAML) · Model (MJCF)