Electricity: motive power systems – Automatic and/or with time-delay means
Reexamination Certificate
2000-08-28
2001-12-11
Masih, Karen (Department: 2837)
Electricity: motive power systems
Automatic and/or with time-delay means
C318S444000, C318S443000, C318S461000, C318S468000, C318S466000, C318S282000, C318S476000, C318S465000
Reexamination Certificate
active
06329779
ABSTRACT:
TECHNICAL FIELD
This invention relates to a method of operation for a motor-driven panel, such as a window, and more particularly to a method for triggering a reversal of the motor when the panel is driven into contact with an obstacle.
BACKGROUND OF THE INVENTION
For safety-related reasons, control systems governing the operation of motor-driven automotive panels (such as windows, sliding doors, trunk lids, sun-roofs, etc.) are typically designed to reverse the motor for retracting the panel in response to a detected engagement of the panel with an obstacle prior to reaching a desired position. See, for example, the U.S. Pat. No. 4,823,059, issued Apr. 18, 1989, which detects the presence of an obstacle in the path of a motor-driven deck lid when the motor current exceeds a predefined threshold. In order to avoid false detection of an obstacle, the control must somehow account for normally occurring variations in system voltage, wear and mechanical friction. For example, the control could be designed to measure the speed of the motor or panel, and to detect the presence of an obstacle if the measured speed is suddenly reduced in a range of panel displacement where an obstacle might be encountered. However, if the obstacle is relatively compliant, a sudden change in motor speed may not occur when the panel initially contacts the obstacle, and the control may fail to detect the obstacle as desired. If the detection thresholds are adjusted to increase sensitivity to changes in the measured speed, periodic undulations in the measured speed signal can be interpreted as a speed reduction, leading to false obstacle detection. Filtering may be used to remove the periodic undulation, but the signal delay caused by filtering correspondingly delays detection of the obstacle, which is undesirable.
Accordingly, what is needed is an improved obstacle detection method that is insensitive to variations in system voltage, wear and mechanical friction, and which is capable of reliably detecting the presence of an obstacle, even if the motor speed change due to the panel contacting the obstacle occurs only gradually.
SUMMARY OF THE INVENTION
The present invention is directed to 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.
REFERENCES:
patent: 4823059 (1989-04-01), Compeau et al.
patent: 5334876 (1994-08-01), Washeleski et al.
patent: 6064165 (2000-05-01), Boisvert et al.
patent: 6208102 (2001-03-01), Kikuchi et al.
Hjelmeland Robert W.
Pimley John Thomas
Delphi Technologies Inc.
Funke Jimmy L.
Masih Karen
LandOfFree
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