Patent ID: 8179275

Claim:
A method for determining a failure of a spring in a movable barrier operator system comprising a motor, a spring, and a movable barrier, the motor configured to move the movable barrier between an open position and a closed position relative to an enclosure, the spring coupled to the movable barrier and configured to at least in part counterbalance weight of the movable barrier during movement of the movable barrier by the motor, the method comprising: moving the movable barrier that is at least partially counterbalanced by the spring with the motor from a first position to a second position; during movement of the movable barrier to the open position or during movement of the movable barrier to the closed position by the motor, monitoring at least one characteristic of the movement of the movable barrier; comparing the at least one monitored characteristic measured during only one of: moving the movable barrier from the closed position to the open position, or moving the movable barrier from the open position to the closed position, to a criterion related to the movement of the movable barrier not based on a movement of the movable barrier immediately preceding the movement or cycle during which the characteristic is measured; wherein variance from the criterion is indicative of spring failure; and setting an alarm condition to indicate a failure of the spring when the at least one monitored characteristic does not meet the criterion.