researchers at keio university in japan have developed a robotic tail that humans can wear to improve balance. called ‘arque’, it was inspired by the way animals passively use their own tails to improve mobility by shifting their center of gravity.

'arque' is a robotic tail that improves human agility and balance

images courtesy of keio university



arque consists of interlocking plastic vertebrae that use a spring-based structure to handle shearing and tangential forces. each vertebral joint is made up of one central plate, surrounded by an additional four protective plates, with the plates being linked together with elastic cords. because of the modular, additional segments can be added, or removed, making the rail heavier or lighter depending on the wearers physique


the internal structure of the tail uses four pneumatic artificial muscles that use compressed air to provide force on eight directions depending on the actuated muscles. the tail is strapped around the user’s waist, and the user dons a wearable body tracker that determines the user’s approximate center of gravity, which then prompts the tail to move and adjust itself accordingly as a corrective counterbalance.

'arque' is a robotic tail that improves human agility and balance



‘for most vertebrate animals, tail plays an important role for their body, providing variant functions to expand their mobility,’ reads a statement outlining the project. ‘in this work, arque, we propose an artificial biomimicry-inspired anthropomorphic tail to allow us to alter our body momentum for assistive and haptic feedback applications.’

'arque' is a robotic tail that improves human agility and balance



researchers studied the tail of the seahorse as its structure can handle a high amount of forces, relative to its size. appendages in animals are typically round, but the seahorse tail has a square cross section with each vertebra surrounded by four, interlocking L-shaped plates.

'arque' is a robotic tail that improves human agility and balance



the team imagines a number of potential uses for the device, including combining it with sensors or linking it up with brain signals to create an artificial limb. it also imagines using use the tail as a gaming device to enhance user experience as wearers explore virtual worlds.


project info


research body: keio university

name: arque

type: wearable technology