US Patent 8182003 Exit device and method of operating the same

The invention provides a method of operating an exit device. The exit device includes a locking mechanism for locking and unlocking a door, the locking mechanism having a latch bolt movable between an extended state and a retracted state, and a link connected to the latch bolt and movable between locked and unlocked positions, movement of the link between the locked and unlocked positions causing movement of the latch bolt between the extended state and the retracted state to lock and unlock the door, and a motor operably connected to the link. The method comprises operating the motor to move the link in a first direction toward the unlocked position, the motor being operated until the link reaches a hard stop position; thereafter determining a soft stop position based on the hard stop position; and thereafter selectively using the motor to move the link in the first direction toward the unlocked position, the motor being operated only until the link reaches the soft stop position.