Exploring Soft-Bodied Animals, Building Soft-Bodied Robots
Many animals can produce high-power movements seemingly beyond the capability of their muscles. Animals with stiff skeletons accomplish this feat by storing energy in specialized structures and releasing it quickly, with added mechanical advantage provided by levers and joints. While soft and flexible animals—those without internal or external skeletons—can also move quickly, how they accomplish this is not known.
Robert F. Shepherd, Mechanical and Aerospace Engineering, along with collaborators at Tufts and Johns Hopkins Universities, is exploring three new hypotheses about rapid, repeatable movements in soft animals. First, soft-bodied animals can stiffen their bodies by muscle, then suddenly but controllably, buckle their bodies to generate powerful movements. Second, much of the energy for this process is stored in elastic proteins in the muscle itself. Third, animals can control the magnitude, direction, and timing of the explosive release to make it directional and useful.
The team of biologists and engineers is examining these novel mechanical and neural mechanisms by ascertaining basic mathematical principles with mechanical muscle models; studying fast movements, particularly rapid escape and defense behaviors, in fish and caterpillars; and building computational and physical models that demonstrate how basic principles can be emulated or exceeded in soft machines. These machines will be built using the latest three-dimensional printing technologies to explore new mechanisms of actuation and recovery. The overall goal is to identify common underlying principles governing repeatable, impulsive movements and to use this fundamental theoretical framework as the basis for new engineered devices.
Controlling instabilities to generate goal-directed, extreme, and high-power maneuvers is of general interest to the United States Department of Defense. The results of this effort could be used for building robots that swim or run through unpredictable terrain and marine environments, as well as for constructing artificial limbs, rapid actuation systems, actuators, and dexterous manipulators.