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Open-Bionics / Brunel

Design files relating to the Brunel Robotic Hand
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Finger dislocation #28

Closed JonathanRaines closed 7 years ago

JonathanRaines commented 7 years ago

When the fingers are pulled hard enough, the ligaments can be dislocated. The ridge is pulled out the trough and pops into the interphalangeal space.

The fingers can be dislocated by pulling on them directly, or by applying leverage using a lateral load.

The distal phalanges appear to hold the ligament better. Although both joints dislocate, it's always because of the proximal phalanx.

JonathanRaines commented 7 years ago

The proximal phalanx has the least positive hold on the ligament. The spring-back elastic is at present flat against the ligament. This prevents protruding hooks like on the distal ligament and the knuckles.

JonathanRaines commented 7 years ago

The proximal phalanx is held together by one M2 bolt at the midpoint. It's therefore in the worst place to clamp either end together around the ligament. However, the spring-back elastic has to have room to go over it and having one at each ends increases assembly complexity.

JonathanRaines commented 7 years ago

The ligament resting length appears too long. Check the hook modifiers etc are working correctly.

Opened as separate issue. #30

JonathanRaines commented 7 years ago

Copying the distal phalanx, the hook on each end was raised. Recesses were made in the top cover for it. The hooks slotting into top cover also prevent the top cover rotating so added bonus there. The elastic has to rise off the mid-plane slightly more sharply to avoid the raised hook. Need to implement on all fingers now.