Dynamical Modeling of the “Power Ball” Considering the Transition Between the Rolling Mode and the Sliding Mode

Abstract

The gyroscopic exercise tool which utilizes a gyroscopic effect caused by the whirling motion of a high-speed rotating body to train the antebrachial muscle is considered. When an input motion of 3–5 Hz is added to the case, the rotor spins at thousands of rpm whirling with a precession motion which is synchronous to the input motion given to the case. This tool utilizes a contact phenomenon between the rotor and the case to generate this high-speed spin motion. This paper develops its dynamical model considering the transition among noncontacting, rolling, and sliding conditions. The dynamical characteristics of its motions are numerically investigated and are also confirmed in the experiment.