Extended Reality Waterball for Spinal Rehabilitation

We propose the use of a waterball (water-walking-ball) for physical exercise (spinal rehabilitation) using an IMU (inertial measurement unit) for realtime tracking of the ball's orientation in a feedback loop with a head-mounted display worn by the occupant of the ball. The display functions like a flight simulator or video game, in which the ball becomes the game-controller (interface) for a simple physical exercise activity of walking while maintaining the polar axis as horizontal (or as vertical) as possible. A score is generated by computing the time-integral of the tilt away from this horizontal line, which becomes an error function to be minimized.