Latch-based control of energy output in spring actuated systems

The inherent force-velocity trade-off of muscles and motors can be overcome by instead loading and releasing energy in springs to power extreme movements. A key component of this paradigm is the latch that mediates the release of spring energy to power the motion. Latches have traditionally been considered as switches; they maintain spring compression in one state and allow the spring to release energy without constraint in the other. Using a mathematical model, we demonstrate that changing the parameters of a simplified contact latch (latch radius and release velocity) can enable both this instantaneous energy release behavior as well as a regime that reduces and delays the energy released by the spring. This is true even for latches found in biology that have rounded edges and do not geometrically disappear instantaneously. We also identify a critical threshold between these instantaneous and delayed regimes. We validate this model in both a physical experiment as well as with data from the Dracula ant, Mystrium camillae, and propose that latch release velocity can be used in both engineering and biological systems to control energy output.