Tufts University Groundbreaking Research On Caterpillar Locomotion

Trimmer recently received his third National Science Foundation grant, totaling nearly $1 million to date, to support this research.

An associate professor of biology in the School of Arts and Sciences at Tufts with expertise in cellular biology and neurophysiology, Trimmer has appointments in biomedical engineering at Tufts' School of Engineering and in neurosciences at Tufts' Sackler School of Graduate Biomedical Sciences.

"We are trying to understand how the nervous system controls these complex movements so we can replicate that movement and build our own soft-bodied robots that maneuver easily, like a caterpillar," Trimmer said.

He added, "Our research has potential applications in the design and control of a new type of flexible robot that could be used to navigate through pipelines or intricate structures such as blood vessels and air tubes, as well as space shuttle operations and building construction."

Trimmer's lab is believed to be the only one of its kind to focus on the locomotion of soft-bodied insects, specifically the nervous system and how it works with the biomechanics of the caterpillar. (There are many biologists and engineers that study animals with skeletons and joints with a goal of building jointed, but not flexible robots.)

Two specific aspects of the caterpillar's movement are being examined in detail: first, the research is trying to understand how crawling is controlled by the central nervous system and how it interacts with peripheral structures such as muscles and cuticles. Second, the unique ability of caterpillars to climb using curved hooks at the tips of the abdominal prolegs is being examined. This gripping is passive but very strong (similar to Velcro hooks) and can be actively released.

To examine these questions, Trimmer and his research team are using 3D kinematics, electromyography, hydraulic measurements, magnetic resonance imaging, 3D modeling and animation and biomaterials testing.

Caterpillars provide a useful survival model: They do not escape predators by running but instead use camouflage, chemical defenses and cryptic behavior. As a result, their movement – crawling – has evolved into a highly specialized form of locomotion which allows soft-bodied animals to crumple, compress and rotate body parts into confined three-dimensional structures such as tubes and branches.

Trimmer is working with Tufts colleagues across the University in physics, mathematics and mechanical engineering, and often employs undergraduate researchers as well. The majority of the knowledge about how humans move is based on research about creatures that walk, fly or swim using hard bones and exoskeletons (a hard outer structure that provides protection or support). By looking at soft bodied animals like the caterpillar, Trimmer can copy some of the unique ways in which they move.

This summer, the team will begin to design a physics-based computerized simulation model of the locomotion, and it hopes to have an operating prototype ready next year.

"We need to solve the artificial muscle problem first, currently there are no good soft actuators (motors) available," according to Trimmer.

"Professor Trimmer is a trailblazer in the field of biosystems and neural processes," said Susan Ernst, a biologist and dean of the School of Arts & Sciences. "His work could help scientists and engineers around the world navigate complex and even dangerous situations."

Trimmer – who is from Leicestershire County, England, and has been at Tufts since 1990 – has presented his work on the neural control of soft-bodied locomotion at several meetings over the past two years, including the British Biochemical Society, the East Coast Nerve Net meeting, the Society for Neuroscience Annual Meeting, and the Society for Integrative and Comparative Biology's annual meeting.

For more information on Trimmer and other neural processes work being done in his lab, see: http://ase.tufts.edu/biology/faculty/trimmer/.

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Tufts University, located on three Massachusetts campuses in Boston, Medford/Somerville, and Grafton, and in Talloires, France, is recognized among the premier research universities in the United States. Tufts enjoys a global reputation for academic excellence and for the preparation of students as leaders in a wide range of professions. A growing number of innovative teaching and research initiatives span all Tufts campuses, and collaboration among the faculty and students in the undergraduate, graduate and professional programs across the University's eight schools is widely encouraged.