US Patent 9114536 Electronic emergency-stop braking circuit for robotic arms

Representative embodiments of a system for braking a cyclically rotating motor upon a power failure include (i) charge-storage circuitry for storing charge and converting the stored charge to an output voltage upon power failure; (ii) one or more passive electrical elements for conducting current induced by motor rotations; and (iii) voltage-actuated circuitry connected to the passive electrical element and the charge-storage circuitry for braking the motor during each half-cycle of motor rotation. The circuitry is inactive until actuated by the charge-storage circuitry upon power failure.