Abstract

Powerball is commercial name of a gyroscopic device that is marketed as a wrist exercisers. The device has rotor with two unactuated DOFs and can be actuated with suitable motion of additional human or robot wrist axis. After initial rotor’s spin, applying the properly torque about wrist axis lead to spin-up of the rotor. Finding this torque intuitively is easy job for most peoples, but not so easy for technical consideration for example in robotics.  The article's main contributions are dynamic models with considered friction effects. Working principles of this device in all three modes: free rotor and both modes of rotor rolling in the housing are described. The work introduces reduction to 1 DOF excitation, considering preliminary research results, which enables laboratory control experiment. Estimation of friction parameters is also discussed. Both, the simulation with animation and experimental results are presented.