User:Ophiuchusstars3/sandbox/Hoberman mechanism

The Hoberman mechanism, invented by American architect, engineer, and artist Chuck Hoberman, is a system enabling expandable structures such as self-building tents and certain children's toys, specifically his "Hoberman sphere", to change in size significantly.

Structures with this mechanism typically have rigid, identical parts linked together around pivots (rotation points). These individual parts can be made from numerous materials depending on the purpose of the structure. For example, the framework of a self-building tent would be made from hard, durable materials like aluminum or steel, and a Hoberman sphere designed for children would be made from a light, colorful material like plastic. This allows the structure to have the greatest range when the links are moved, and form a larger final shape, or fold into a smaller compact structure for storage. The overall structure, and its individual parts, can have any three-dimensional shape, allowing a variety of structures to be designed for different applications, such as screens and radio antennas.

History
Through experimentation, Hoberman invented ways for structures of a multitude of different shapes to grow and shrink in size simultaneously.

Early Days
Beginning with his question of how to "make objects shrink in size", Hoberman experimented with origami and observed the way they folded and changed shape. He later worked with interwoven metal parts linked in pivots, which proved to increase the volume of the object significantly. Hoberman eventually patented some of the linkage systems he devised, and even manufactures them at his company Hoberman Associates.

Synchronized Ring Linkages
The ring linkage system was developed in 2004 and is made of at least six linkages connected into a ring-like shape. The structure can grow into a ring-like shape or shrink into a star-like shape with the linkages pushed close together for efficient space storage. These properties make ring linkages useful for structures that require its surface area to be changed.

Folding Covering Panels for Expanding Structures
In 2005, Hoberman released a linkage system of bars interconnected into scissors-like pivots, whose overall structure is a triangle that can expand or contract. This structure is to be used with a foldable covering panel connected to the bars so that the cover can spread out with the structure, or compress into a smaller polygonal shape. Like the four-bar linkage system, the folding panel can be used to set up temporary shelters, in addition to foldable projection screens and transformable lighting products.

Synchronized Four-Bar Linkages
In 2006, Hoberman developed a linkage system of interconnected linkages, with each one made up of four bars. Two of the bars are designed to lift and support the remaining two bars like pillars, forming a trapezoidal shape. The linkages are to be lined parallel to each other, so that when activated, the system would build itself into a tent frame, which is useful when one must rapidly set up temporary shelters.

Panel Assemblies Having Controllable Surface Properties
Made of at least one fixed panel and a minimum of two movable panels, Hoberman developed a design for controllable panel assemblies in 2010. With at least two drive links, each with its own pivot connected to the panels, the panels can move in a way that aligns them to the fixed panel, each other, or not align with any other panel. The panels can be perforated (filled with holes) or be made of a colorless material with an applied graphic pattern. The sheets can be transparent when aligned, and opaque when unaligned, helping control a building's internal temperature through shading. (see also passive cooling)

Applications
Hoberman's mechanism is common in the toys he invented, namely the Hoberman sphere. Besides its use in toys, engineers are constantly discovering new ways to apply this system.

Children's Toys
While Hoberman's sphere is his most known toy, there are other toys that use the same mechanism.

Hoberman Sphere
In contrast to its name, the Hoberman sphere has a polyhedral structure, or is three-dimensional and made up of smaller individual triangles, and can expand or contract at a constant speed due to its linkage system. When the sphere contracts or expands, the distance between each pivot decreases or increases, allowing the structure's individual parts as well as the whole sphere to change size with the same speed. The Original Hoberman Sphere, one of the largest of its kind, was displayed at the central exhibit of the atrium of the Liberty Science Center in New Jersey. First installed in 1992, then moved to the museum's new entrance hall in 2007, the 317 kilogram (700 pound) sphere is hung by cables and automatically expands and contracts.

Switch Pitch Toy
Beginning production in 2001, the Switch Pitch toy is a ball made to switch the inner and outer layers of the sphere when thrown into the air, thus changing its color. This toy won the Oppenheim Platinum Award for Design and was featured on the HBO comedy series Silicon Valley.

Hoberman Arch
In the 2002 Winter Olympics at Salt Lake City, Utah, the Hoberman arch was used as a screen to be opened before revealing the stage for awarding medals.

POLA Ginza Façade
At the request of POLA, a Japanese cosmetics manufacturer, Hoberman designed a shading system with help from design architect Yasuda Atelier and executive architect Nikken Seikei, for its new building in the Ginza district in Tokyo. Opening in 2009, the fourteen-story complex has 185 controlled panel mechanisms inside the double windows of the building's front side. Each panel is roughly 1 meter (3.28 feet) by 3 meters (9.84 feet) and is made from a curved acrylic sheet.

Microwave Antennas
The properties of a microwave antenna can be changed if its surface area changes, enabling one antenna to perform multiple functions, specifically by tuning its frequency. This design has two partially rigid pieces linked together with pin joints that adjust the two actuation (operation) rings' surface area when necessary.