Millions of years after human ancestors lost their tails, researchers at Keio University in Tokyo are bringing the appendage back in robotic form. They have developed a wearable robotic tail designed to enhance human balance and mobility, offering a unique solution to assist the nation’s rapidly aging population.

The one-meter-long device, dubbed “Arque,” attaches to the wearer’s waist via a harness and is engineered to function like the tail of a cheetah or a monkey, acting as a pendulum to maintain equilibrium.

The technology is inspired by biomimicry, specifically the seahorse tail, which is known for its incredible strength and flexibility due to its boxy, interlocking vertebrae.

• Active Counterbalance: The tail uses a system of four pneumatic artificial muscles powered by compressed air, allowing it to move dynamically in eight directions.
• Real-time Response: A wearable body tracker monitors the user’s center of gravity. When the user tilts their body one way—such as while walking over uneven ground or bending to lift an object—the tail automatically swings in the opposite direction to counteract the movement, restoring balance.
• Elderly Assistance: Researchers believe Arque could significantly reduce the risk of falls and injuries for the elderly, helping them walk more confidently and steadily and remain independent for longer.

While the initial focus is on assisting the elderly, the team is exploring other applications for the innovative prosthetic:

• Industrial Use: It could serve as a balancing aid for warehouse workers carrying heavy, off-center loads, helping to reduce strain and increase stability.
• Virtual Reality (VR): The tail could provide a unique form of haptic feedback in VR environments, altering the player’s balance to simulate strong winds or unstable terrain for a more immersive experience.

The Arque tail remains a prototype, but its development showcases Japan’s commitment to technological solutions for its demographic challenges, merging ancient biological principles with cutting-edge robotics to augment human function.