A Hoberman sphere is an isokinetic structure, patented by Chuck Hoberman, that looks like a geodesic dome but can fold to a fraction of its normal size with the scissor-like action of its joints.
Colored plastic versions have become popular as children's toys: Various toy sizes are available, with an original design that can expand from 5,9 inches (15 cm) in diameter to 30 inches (76 cm).
A Hoberman sphere typically consists of six large circles corresponding to the sides of an icosidodecahedron. The Hoberman orb can be unlocked by allowing certain members to separate from each other. The work of each joint is linked to the others in a scissor mechanism, such as those used to mount pantograph mirrors or how a folding chair works. On larger models this can be accomplished by feeding a rope or cable instead.
The largest Hoberman sphere available is at the AHHAA Science Center in Tartu, Estonia. Fully expanded, it is 5,9 meters (19 ft) in diameter. The motorized sphere weighs 340 kilograms (750 lb), is made of aircraft-grade aluminum, and constantly oscillates between its compact and expanded states. The Sphere hangs above the Center's Science Court and is operated by a computer-based motion control system. This system turns the sphere on and off with a programmed series of lyrical movements choreographed with music, lighting, and special effects.
An earlier, similar but slightly smaller Hoberman sphere is in the atrium of the Liberty Science Center in Jersey City, New Jersey. The 700-pound (320 kg) sphere is 18 feet (5,5 m) in diameter when fully expanded.[
In 1993, a second geodesic sphere was installed at the Swiss Science Center Technorama in Winterthur, Switzerland.
Source: Wikipedia
Günceleme: 01/09/2021 22:05
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