Door opener control with adaptive limits and method therefor

DETAILED DESCRIPTION It is therefore an object of the invention to set or reset sensitivity limits in accordance with the forces operating on the door not only in conjunction with a learn mode but throughout the operating mode as well, thereby maintaining a current basis for the sensitivity limits and permitting small offsets which are indicative of excess force caused by an obstruction.
It is also an object of the invention to increase the sensitivity to an obstruction during the final several inches of door closing.
Another object of the invention is to set or reset the down position limit in accordance with the detected position of the floor, not only in learn mode but throughout the operating mode as well.
The garage door operator has a motor for driving the door in each direction and sensors which detect motor rotation.
The number of rotations is counted to measure the distance travelled using the fully open position as the zero position.
The motor speed and deceleration are determined from the time elapsed per revolution and its variance from the preceding revolution.
Door opening or closing loads cause the motor speed to drop below a nominal no-load value and the lowest speeds reached during successful opening and closing, respectively, minus an offset are used as the sensitivity limit settings.
Any motor speed lower than the respective sensitivity limit is presumed to be caused by an obstruction.
When such a speed is reached during a closing movement, the door is stopped and then opened.
If the limit speed is reached during an opening movement, the door is merely stopped.
The operator circuit is based on a microcomputer which is programmed to function in a learn mode for initial setting of the limits, and in an operate mode for controlling the door to operate in accordance with the limits an to update the limits each time the door successfully completes its travel.
Initial motor speed settings for different sensitivity levels are stored in the microcomputer.
The operator has separate manually actuated up and down learn switches or push buttons