Obstacle detection method for a motor-driven panel

Abstract

An improved method of detecting the presence of an obstacle in the path of a motor-driven panel by computing the slope of a measured motor speed signal in a way that cancels the effect of periodic undulation of the speed signal, and comparing the computed slope to a slope threshold that is selected as a function of the average motor speed. A position sensor produces a series of pulses corresponding to panel movement, and a microprocessor-based controller stores an array of speed-related samples corresponding to the time periods between successively produced sensor pulses. The average speed is computed at two different points in the array, and the slope of the stored speed samples is determined according to a difference between the computed average speeds. Periodic variation in successive motor speed samples due to a periodic variation in the sensor pulse spacing has a repetition interval corresponding to a fixed number of samples, and the average speeds are computed based on speed samples that are separated by one-half of the repetition interval to substantially eliminate the effect of the periodic variation. The slope threshold for obstacle detection decreases with increasing average motor speed so that obstacle detection occurs when the obstacle exerts a given force on the panel, regardless of the panel speed.

Dependencies are inferred from the claim text.