Tendon Material (UHMWPE)

The high-strength, low-stretch, abrasion-resistant synthetic cord commonly used as tendons in tendon-driven dexterous hands.

Ultra-high-molecular-weight polyethylene fiber (UHMWPE, sold under brand names like Dyneema and Spectra) is spun from polyethylene chains that are extremely long, which gives it far more strength per unit weight than steel wire, along with low stretch, a low friction coefficient, and good resistance to repeated bending. A tendon-driven dexterous hand has to carry pulling force from motors in the forearm, through pulleys or guide tubes at the wrist and finger joints, all the way to the fingertip: if the cord stretches, finger position becomes inaccurate, and if it frays and snaps, the hand stops working — so designers reach for this braided fiber. Its weak points are poor heat resistance and slow creep (gradual stretching) under sustained load, so designs usually add pre-tensioning and tension compensation to work around that.

ExampleMany open-source tendon-driven hands simply use braided PE fishing line — the same material sold for high-strength fishing line — as the tendon.

Also called

Ultra-High-Molecular-Weight Polyethylene Fiber, UHMWPE Fiber, Dyneema, Spectra, Braided PE Line

Related

Tendon-Driven Actuation · Tendon Routing Configurations (N / N+1 / 2N) · Dexterous Hand · Bowden Cable · Tesla Optimus Hand

Sources

Ultra-high-molecular-weight polyethylene - Wikipedia
Dyneema - Wikipedia