Researchers at Keio University in Japan have developed “Arque,” a robotic tail that humans can wear to improve balance. The device was informed by the ways animals passively use their tails to shift their center of gravity.
Arque consists of interlocking plastic vertebrae that use a spring-based structure to handle shearing and tangential forces. Each vertebra is controlled by four “muscles” fed by a mesh-covered expandable bladder that uses compressed air. The air provides force on eight directions depending on the actuated muscles. The vertebrae can be weighted and segments of the tail can be added or removed to adjust the weight to the wearer’s body.
The tail is strapped around the user’s waist and the user wears a body tracker to determine approximate center of gravity, which then prompts the tail to move and adjust accordingly as a corrective counterbalance.
Researchers studied the tail of the seahorse because its structure can handle a high amount of force 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.
The team imagines a number of potential uses for the device’s intended ability to alter body momentum for assistive and haptic feedback. Applications could include combining Arque with sensors, linking it to brain signals to create an artificial limb, or enhancing gamers’ experiences as they explore virtual worlds.