Answer: For balance and agility.
It works for lots of other animals, so why can’t it work for humans too?
Unlike the many aesthetic robotic tails already out there, the Arque tail was designed for more utilitarian purposes. The scientists at the Keio University Graduate School of Media Design who created it envision a range of practical uses for it like helping people to lift heavy objects or move more easily if they have limited mobility.
Modeled after a seahorse’s tail, the device consists of spring-loaded joints that can be added or removed to change its length. Together they form a connected vertebrae powered by artificial muscles that move the tail to alter the wearer’s center of gravity. Additionally, a body-worn tracker allows the tail to monitor its wearer’s movements and keep up with them in real time.
In addition to maintaining balance and improving agility, the tail might also find use in virtual reality applications. For example, if someone is walking against a strong wind in virtual reality and wants to lean forward, the tail could be positioned to counteract their balance and allow them to do that.