An actuator is provided having an electric motor that generates a back emf. The actuator also includes a control system for controlling the speed of the electric motor. The control system includes a controller and circuitry for allowing the controller to sample the back emf of the motor. The controller...http://www.google.es/patents/US6954044?utm_source=gb-gplus-sharePatente US6954044 - Electric motor with speed control
