Tiny punching "robot" mimics the mechanism of the mantis shrimp
Among other things, the mantis shrimp is known for having the fastest punch of any animal. Harvard scientists have now built a mechanism that simulates that punch, and they believe that it could lead to new capabilities for human technologies.
In order to deliver its lethal punch, the shrimp starts by building up pressure in the muscles of two club-like appendages. Within the tendons of those muscles are two small structures known as sclerites. These work like a latch, initially holding the "spring-loaded" muscles back, but then allowing them to release their stored energy all at once. As a result, the two clubs shoot forward faster than a bullet leaving a gun.
One thing that had previously been noted, however, was the fact that there is a slight delay between the sclerites releasing the appendages, and the appendages moving forward. In order to better understand what purpose this serves, a Harvard University team led by Prof. Robert Wood built a 1.5-gram shrimp-scale "robot" that replicates the mantis shrimp's club mechanism.
Although the device doesn't quite match the punching speed of the shrimp, it is able to move faster than any other similar device built at the same scale – its arm hits a speed of 26 meters (85 ft) per second. Additionally, as is the case with the shrimp, it was found that when the robot's equivalent of the sclerites are released, there is a delay before the arm shoots forward.
By analyzing ultra-slow-motion footage of both the shrimp and the robot, the scientists came to the conclusion that after the sclerites are released, the structure of the muscles themselves serves as a sort of secondary latch. Such an arrangement helps control the movement of the appendages, holding them precisely in place until they reach a tipping point at which they shoot forward.
"This process controls the release of stored elastic energy and actually enhances the mechanical output of the system,” says graduate student Emma Steinhardt. "The geometric latching process reveals how organisms generate extremely high acceleration in these short duration movements, like punches."
It is now hoped that this new understanding of the mantis shrimp could one day lead to increased functionality of robots and other devices.
A paper on the research, which also involved Duke University, was recently published in the journal Proceedings of the National Academy of Sciences. You can see the shrimp and the robot in action, in the following video.