Modelling of the robotic Powerball®: a nonholonomic, underactuated and variable structure-type system

  title={Modelling of the robotic Powerball{\textregistered}: a nonholonomic, underactuated and variable structure-type system},
  author={Tadej Petri{\vc} and Boris Curk and Peter Cafuta and Leon Žlajpah},
  journal={Mathematical and Computer Modelling of Dynamical Systems},
  pages={327 - 346}
The Powerball® is the commercial name for a gyroscopic device that is marketed as a wrist exerciser. The device has a rotor with two underactuated degrees of freedom, which can be actuated by the appropriate motion of human or robot wrist axes. After the initial spin, applying the appropriate motion and torques to the housing leads to a spin-up of the rotor. Finding these torques intuitively is an easy task for human operators, but a complex task for a technical consideration, for example, in… 
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