1 January 2002
Roborake to the plant floor?
By Bob Felton
NASA's Jet Propulsion Laboratory is developing miniature rakes with electroactive-polymer (EAP) tines that emulate human muscles to remove soil, dust, and other loose, particulate material from solid surfaces. Developed to clean rock surfaces for photography during geological exploration of Mars, the technology is available for licensing.
The miniature electroactive-polymer rake (MEAR) is a low-power device that removes soil, dust, or other loose particulate matter from the surfaces of solid objects. It closely resembles an ordinary rake. Unlike the tines of a rake, however, the tines in a MEAR are actuator fingers that bend under electrical control. Each tine consists of a sandwichlike composite comprised of an inner, ion-exchange membrane between two gold- or platinum-coated polymer layers that serve as electrodes. The amount and direction of bending depends on the magnitude and polarity of the applied voltage. An alternating voltage causes a raking or sweeping action.
Small, stiff fibers attached to the end of the tines enhance the cleaning action. Copper grounding wires on the tips prevent accumulation of static electric charges caused by the sweeping.
It was difficulties that arose during the Mars Pathfinder mission that provided the impetus for development of MEAR. "Recent lessons learned from Mars Pathfinder," the inventors explained, "raised the need of planetary geologists to remotely expose surfaces of rocks and other explored materials. The use of mechanical/robotic arms to perform such a function can be complex, clumsy, expensive, [and] cumbersome and consume critical mission resources. The required function is to carefully displace soil, dust, loose gravel, or other powdery ground substance that obscures the ability to visually examine planetary geological objects."
Researcher Dr. Yoseph Bar-Cohen said, "When it comes to space applications, electroactive polymers are changing the paradigm about the complexity of robots. In the future, we see the potential to emulate the resilience and fracture tolerance of biological muscles, enabling us to build simple robots that dig and operate cooperatively like ants, soft land like cats, or traverse long distances like a grasshopper."
EAP could someday replace damaged human muscles, said Bar-Cohen, leading to "bionic" men and women. "My hope," Bar-Cohen said, "is someday to see a handicapped person jogging to the grocery store using this technology." IT