A froghopper can jump more than 100 times its body length. A trap-jaw ant can go from a complete standstill to 140 mph in less than a millisecond. But how in the world do they do it?
A new mathematical model, published Thursday in Science, helps explain how such small creatures can reach blinding speeds. The findings could also help robotics overtake nature, at least in one area.
The key for these tiny creatures lies in how they store and release energy. Where humans use muscles, these small animals use spring-like parts to achieve those high speeds. Previous models looked at the physical tradeoffs of muscles, but didn’t take into account the spring and latch-like mechanisms. This study takes into account the compromises of those mechanisms that many tiny creatures have.
Working Together is Key
Mark Ilton and colleagues included size and acceleration information for more than 100 species in their dataset and then compared it to nature-inspired small robots. The spring systems they looked at, both biological and mechanical, consist of a motor, spring, latch and projectile. Latches control the release of a lot of energy over a short period of time and the shape and release time can affect how they perform. Insects including fleas, leafhoppers and froghoppers rely heavily on latches and springs working closely together to gain such high speeds in short timeframes.
They also found that the stiffness of the spring must be carefully balanced with motor properties, discovering that “a large spring is slowed down by its own force-velocity trade-off, whereas a small spring is more likely to fail.” That likely helps explain why mid-size insects tend to jump faster than small or large ones.
This model could help researchers further understand spring-powered animals. Not only that, but it could help robots become impeccably small and fast.
“If you have a particular size robot that you want to design, for example, it would allow you to better explore what kind of spring you want, what kind of motor you want, what kind of latch you need to get the best performance at that size scale, and understand the consequences of those design choices,” said Sarah Bergbreiter, co-author of the study and an associate professor of mechanical engineering at the University of Maryland, in a news release.