Have you ever been on a bus when the driver had to suddenly brake on a dime and you are thrust forward? You feel almost as if your guts are coming up. Actually, they are, as are other soft tissues in your body that have been jossled at that moment; they are controlled by gravity.
Manuca sexta Caterpillar, a gravity-defying little critter: image from Tufts University School of Arts & Sciences via ScienceNow
But scientists at Tufts University Trimmer Lab have been studying a specific kind of caterpillar - the tobacco hornworm, or Manduca sexta - and learned that, when moving forward, the caterpillar's guts precede its movement, not coincide with it, in a non-gravity controlled manner. The Manduca also has a gecko-like grip on surfaces, which defies gravity as well. These two fascinating aspects of the Manduca, in addition to others found in their studies, make this caterpillar a perfect biomimetic specimen for the Trimmer Lab to help develop its crawling robot.
Because the caterpillars have no bones or hard structures in their bodies, several means of observation needed to occur; so 3D
kinematics, electromyography, hydraulic
measurements, magnetic resonance imaging, 3D
modeling and animation, biomaterials testing,
and muscle work loop analysis were used.
Somehow, all the data from these studies came together in an elegant understanding of the biomechanics of crawling, a finding that will have a dramatic impact on the evolution of a flexible or "soft" robot. Such a robot could be used to travel intricate body structures, such as blood vessels or veins. Or, on a larger scale, a flexible robot might be used to navigate through pipelines or on hilly surfaces.
In this video, the Tufts researchers report on their own findings. It is about 5 minutes long and there are two parts that have some technical interruptions, but stick in there; it's a very elucidating video.
Visceral-Locomotory Pistoning in Crawling Caterpillars is now pre-published online in the journal Current Biology.
Sources: Trimmer Lab, Tufts University; Current Biology, via ScienceNow