Animals with tails have evolved to use their appendages in unique ways. Cheetahs, for example, rotate their tails like a gyro to maintain stability while chasing prey, alligators and crocodiles use them to swim swiftly through water, and some species of monkeys can use them as a third arm to clutch branches while moving from tree to tree. Engineers from Keio University’s Graduate School of Media Design have taken inspiration from those animals to design a robotic tail for humans to enhance our balance and agility.
In a recently released paper entitled “Arque- Artificial Biomimicry-Inspired Tail for Extending Innate Body Functions,” the engineers describe how they designed the artificial limb using inspiration garnered from animals, including seahorses. The tail features a series of interconnected plastic vertebrae, each consisting of four protective plates and a weight-adjustment system that can be optimally configured for users with different heights.
Each joint is outfitted with an elastic cord and spring mechanism, allowing it to deform and move into a position that benefits the wearer’s movements. Each vertebra houses an artificial muscle that actuates the tail using compressed air, meaning the tail has to be tethered to an air compressor to function.
The most obvious application for the Arque tail would be for workers who routinely carry heavy loads, acting as a counterweight that takes the pressure off the worker’s back while moving large objects. Another application see’s the limb used as a full-body haptic feedback system for people exploring virtual worlds, changing their center of mass to reflect the force generated in those worlds, such as virtual winds.