There are several ideas on how to detect direction of motion in the thread at https://forums.homeseer.com/forum/ho...tion-of-motion. In that thread I posted the Sonoff/MQTT implementation using the IR LED beam break approach where three IR LED receivers were mounted in a Sonoff Basic case and provided some of the lessons learned from the exercise. In that thread I indicated disappointment in the maximum distance of the IR beam which was about one foot. This is a follow-up to describe success with a a higher power IR LED emitter. The write up of the implementation is in Section 13.8 of mcsMQTT.pdf (http://mcsSprinklers.com/mcsMQTT.pdf).
The new IR LED emitters are rated at 100 ma vs. the assumed 20 ma in the original implementation. This changed the effective beam distance from one foot to three feet, but it did make pointing of the LEDs very sensitive. Small angle of misalignment would make the circuit non-functional. In a third implementation I used three emitters in parallel as shown the picture. This showed to provide two benefits. One is that distance increased to four feet. Further Increase to 52 inches resulted in false beam-break reports. The second is that the alignment is not as sensitive. I actually found that a perpendicular alignment of emitter threesome vs. received threesome provided easier alignment. I suspect this means that in my case the vertical rather than horizontal alignment was more sensitive. I believe that commercial beam-bream implementations over long distance, such a garage door safety, use lens to help with beam focus and alignment.
Overall I consider the very simple circuitry of IR LED and resistor pairs to be quite viable for motion direction detection for selected situations. The span of beam separation becomes the limiting factor. Mounting on a doorway which is typically three feet of narrower would be a good use case. A staircase which is typically under four feet wide is another. Pet doors have very small spans so even the original implementation of a single 20 ma IR LED receiver will work well.
The new IR LED emitters are rated at 100 ma vs. the assumed 20 ma in the original implementation. This changed the effective beam distance from one foot to three feet, but it did make pointing of the LEDs very sensitive. Small angle of misalignment would make the circuit non-functional. In a third implementation I used three emitters in parallel as shown the picture. This showed to provide two benefits. One is that distance increased to four feet. Further Increase to 52 inches resulted in false beam-break reports. The second is that the alignment is not as sensitive. I actually found that a perpendicular alignment of emitter threesome vs. received threesome provided easier alignment. I suspect this means that in my case the vertical rather than horizontal alignment was more sensitive. I believe that commercial beam-bream implementations over long distance, such a garage door safety, use lens to help with beam focus and alignment.
Overall I consider the very simple circuitry of IR LED and resistor pairs to be quite viable for motion direction detection for selected situations. The span of beam separation becomes the limiting factor. Mounting on a doorway which is typically three feet of narrower would be a good use case. A staircase which is typically under four feet wide is another. Pet doors have very small spans so even the original implementation of a single 20 ma IR LED receiver will work well.
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