Stryker Corporation
Person support apparatus with actuator brake control

Abstract:

A person support apparatus includes one or more motorized actuators that are braked in different manners depending upon whether or not electrical power is available to the control system. When electrical power is not available, a delay circuit delays closing a first switch that, when closed, short circuits the terminals of one of the motors. When power is available, other switches are opened and closed in a manner that short circuits the terminals of the motor while the first switch remains open. The other switches may be part of an H-bridge. The control system may also detect back emf (electromotive force) generated by the motor when electrical power is available and issue a notification to a technician or other user if an amplitude and/or duration of the detected back emf exceeds a threshold.