Counteracting horizontal accelerations on an elevator car

Abstract

A method and apparatus for actively counteracting a disturbing force acting on a suspended elevator cab in a frame moving vertically in a hoistway is disclosed. A manifestation of the disturbing force such as acceleration is sensed and counteracted, for example, by effectively adding mass to the cab in proportion to the sensed acceleration. This may be accomplished by using an electromagnet actuator for actuating the suspended cab in response to a control signal from a control means which is in turn responsive to the sensed signal. Whatever type of actuator is used, it may be used as well to bring the suspended cab to rest with respect to a hoistway sill prior to transferring passengers. The control means may be analog or digital or a combination of both. A preferred analog-digital approach is disclosed in which the digital part is responsive to accelerometer signals, the analog part is responsive to a force command signal from the digital part and provides a position feedback signal in return. In a preferred embodiment, four electromagnet actuators are situated in the corners of the cab between the floor of the frame and the bottom of the suspended cab. Each actuator may act along a line which intersects the walls of the cab at a forty-five degree angle. A single axis embodiment is also disclosed.