Pneumatic artificial muscles conventional electric motors and hydraulic cylinders. Pneumatic artificial muscles Pneumatic artificial muscles (PAMs) are contractile or extensional devices operated by pressurized air filling a pneumatic bladder. In an approximation of human muscles, PAMs are usually grouped in pairs: one agonist and one antagonist. PAMs were first developed (under the name of "McKibben Artificial Muscles") in the 1950s for use in artificial limbs. The Bridgestone rubber company (Japan) commercialized the idea in the 1980s under the name of Rubbertuators. The retraction strength of the PAM is limited by the sum total strength of individual fibers in the woven shell. The exertion
The King of Limbs Up the Ghost" is an acoustic guitar ballad with layered vocal harmonies. The final track, "Separator", has guitar and piano, a "brittle" drum loop, and echoing vocals. Yorke said he felt "The King of Limbs" was a "visual" album, with lyrics and artwork about "wildness" and "mutating" inspired by his environmental concerns. The album title is thought to refer to the King of Limbs, an ancient oak tree in Wiltshire's Savernake Forest, near Tottenham House, where Radiohead recorded "In Rainbows". At eight tracks and 37 minutes in length, "The King of Limbs" is Radiohead's shortest album. O'Brien explained that Radiohead