Each jaw is attached to one of the two segments, one of which has…
Each jaw is attached to one of the two segments, one of which has teeth outside and the other teeth inside. On turning the shaft carrying the two pinions, one of which gears with one and the other with the other segment, the jaws are brought together with great force.
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
- A pair of tongs with both jaws on one pivot. One jaw carries a segment with teeth outside (pitch radius 19.2 cm), the other a segment with teeth inside (32 cm). The shaft below carries a 12-tooth pinion for the first and a 20-tooth pinion for the second, one in front of the other. The pivot sits at 2 r1 r2/(r2-r1) = 24 cm so both jaws turn at 1/4 of the shaft angle in opposite senses. The shaft (the only driven joint) is rocked by hand, +-1.2 rad. No gravity (flat plan). gen120.py.
- Measured
- Right jaw follows the shaft at -0.2546 (ideal -0.25, r2 0.9999); left jaw at +0.2537 (r2 1.0000). Jaw swing +-0.30 rad for +-1.2 rad of shaft. Penetration 0.02 mm.
- Notes
- The tips come together and open again; they are drawn not to collide. The pivot is placed so the jaws close at equal rates.
Film (MP4) · GIF · Still (PNG) · Spec (YAML) · Model (MJCF)
