US researches have developed a robot that gets about with a pair of flipper-like arms. By recording FlipperBot's adventures using a high-speed camera, the researchers are gaining understanding about the mechanics of traversing "complex surfaces" such as sand.
Though only 19 cm (7.5 inches) long and weighing 790 g (1.7 lb), FlipperBot's limbs span 40 cm (15.8 inches). The arms themselves, powered by small servomotors, are rigid, but have a lightweight board attached at each end, providing the surface area FlipperBot needs to drag itself through sand-like material (the researchers actually use poppy seeds).
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"FlipperBot allowed us to explore aspects of the sea turtle's gait and structure that were challenging, if not impossible, to investigate in field experiments using actual animals," Professor Goldman of the Georgia Institute of Technology said in a press release.
For example, the researchers found that FlipperBot was much more effective when moving with free wrists rather than fixed ones. "[It] allowed the flipper to remain locked in place within a solid region of sand and thus disturbed less material during the forward thrust," Goldman explained. "With a fixed wrist, the robot also interacts with the ground that has already been disturbed by its previous steps, which hinders its movement."
The researchers claim that this finding was borne out by observation of loggerhead sea turtles, filmed by Georgia Institute of Technology researcher Nicole Mazouchova, who built FlipperBot with Dr. Paul Umbanhowar of Northwestern University.
The researchers also discovered that optimal gait was extremely sensitive to change. Minor alterations in FlipperBot's body or movement significantly compromised performance.
The researchers have highlighted numerous potential applications for their work. They hope that FlipperBot may grant new understanding into the evolution of fins and flippers as animals made the transition from water to land. And, that the learning can be applied to future generations of amphibious robots capable of self-locomotion in water or on land using the same limbs.
Perhaps most fittingly, Mazouchova believes that similar research could allow scientists to test the characteristics of beach environments which could help in the conservation of endangered sea turtle species. The effects of disturbed ground on movement may help to explain why some sea turtle hatchlings make more headway than others.
The team's research was published in the April 24 edition of the journal Bioinspiration and Biomimetics. You can see FlipperBot in action below.
Update 04.24.2013: Oh, and if, like us, you were wondering why the researchers use poppy seeds and not sand to test FlipperBot, it's for the benefit of the robot itself. "We have found over the years (going back to our 2009 PNAS SandBot work) that poppies tend to be "gentler" on the robot motors," Professor Goldman told Gizmag. "In early days of testing, little sand grains (which are quite hard) would get inside motors and could damage them. Poppies are larger and softer and didn't seem to do damage to motors." Goldman explained that poppy seeds made "no qualitative changes in locomotor behavior," and are easily ordered on Amazon. So there you have it.
Source: Bioinspiration and Biomimetics