The proposed techniques rely on three principal concepts: (1) controlling the polarity of electromagnets, (2) circulating fluid through a compartmentalized bladder, and (3) expanding and deflating polymers. These designs would allow amorphous robots to move across a surface without conventional wheels or legs. The advantages of amorphous robots would be many, including greater mobility, passive shape changing to allow the robot to pass through odd-shaped openings, and immunity to dust and contamination. This idea is completely scalable from small to enormous robots.

The initial concept was to use a multistage, fluid-filled bladder with circulating high-viscosity fluid. Propulsion is accomplished by moving fluid between different bladder compartments, displacing the robot mass in an arbitrary direction without any external moving parts. This novel method of locomotion allows the entire robot to be sealed in a heavy-duty, fluid-filled bag with a centric electromechanical valve system.

Movement would resemble that of an amoeba, essentially protruding the equivalent of cytoplasm and forming pseudopodia (false feet). The valve system will draw in liquid from the rear compartment, and inject it into the front compartment. The bladder will then inch forward in the direction of the expansion. The meshing along the top and bottom of the compartments is used to gently re-equalize the liquid in the bladder. This process is repeated for continuous movement. More complex omnidirectional movement can be achieved by operating more than one valve simultaneously at varying fluid flow rates. A variation of this design can be achieved by turning the valve system upright, and allowing the compartments to inflate and deflate progressively with high-viscosity liquid. In another embodiment, the amorphous robot would be a long, flexible tube that is propelled by forcing ferro-fluid to move through a movable electromagnetic ring. The polarity of the electromagnet can be easily reversed to change the direction of the inchworm action.

In another concept, the design consists of multiple electromagnetic spheres inside a fluid-filled flexible bladder. The polarity of the electromagnets is sequentially altered to initially force the leadmost ball away from the rest, and then draw the other electromagnets together at the new forward position.

The final design concept incorporates the use of multiple polymer-filled compartments into a large amorphous bag. The individual compartments are sequentially heated or cooled (or electrically stimulated) to cause the polymer to expand or contract. This action is used to roll the bag along the surface.

This work was done by Arthur Bradley of Langley Research Center. LAR-17993-1


NASA Tech Briefs Magazine

This article first appeared in the September, 2014 issue of NASA Tech Briefs Magazine.

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