Morphable Pressurized Tensegrity Cells
Morphable Pressurized Tensegrity Cells (MPTCs) are a technology for producing rigid polymorphic materials and structures that have a low density--generally low enough to float in water, and in some instances low enough to be aerostatic. They consist of a strong impermeable balloon that is internally pressurized by a fluid (gaseous or liquid), a robotic nucleus that is suspended in the core of the balloon, and the tensile actuator-lines that suspend the robotic nucleus and affect the balloon envelope.
|External view of a MPTC, showing attachment locations|
During morphing, different actuator-lines lengthen or contract, pulling the balloon envelope into a different shape. The volume of the balloon remains constant, and so the process does not affect or depend upon changes in internal pressure. This allows morphing to occur quickly and with low energy expenditure. Actuator-line length remains constant during the intervals between shape morphing, maintaining the shape. The compressive strength of a MPT Cell is the result of the internal pressure being higher than the external pressure, and its tensile strength is a result of the high tensile balloon, actuator-lines and nucleus materials.
The cells are pressurized by fluids that are appropriate to their application. MPTCs that operate in deep water marine environments are generally pressurized by fresh water or inert oils. Heavier-than-air varieties that operate in roughly standard temperature and pressure environments are typically filled with local atmospheric gases, pure nitrogen, or CO2. Aerostatic varieties are pressurized by steam (insulated by Vacuum Insulated Membranes), helium or, rarely in Gaian atmospheres, hydrogen, methane, or other light flammable gases.
Cells can be permanently joined together or connected by a reconfigurable extracellular matrix. One design for the extracellular matrix consists of covering the outer surface of each cell's balloon envelope with numerous micro-scale utility foglet-like arms. As MPT Cells are macroscopic, millions, billions, or more such arms cover them. Another method forms the extracellular matrix from robotic myomemetic rope loops. Rope-bots connect specialized cells together by looping through annular attachment points that are integrated onto the external surface of the balloon cell.