I have gotten my garage auto closer system to work fairly well. It detects when a car leaves and waits until the door is not blocked before triggering closing of the door.
The only problem is that the IR sensor (photoelectric with retroreflector) that detects the door blockage status gets saturated by sunlight and think the door is blocked as soon as the sun comes out.
This will only get worse and worse towards winter when the sun decreases it's angle and gets almost impossible to shade at the position of the sensor in the evening and retroreflector in the morning. I also don't know the wavelength of the sensor and have read filters don't always work that well.
What other sensors can I use to detect if the door is blocked? I am considering going back to using ultrasonic sensors on both sides even though I struggled with positioning here to not catch echos or reflections from the ground or garage at large.
I was hoping the photoelectric sensor would just be fool proof, but it's actually even harder to get the work reliably than the ultrasonic sensors.
What other sensors would work well here? I am considering LiDAR, believe it or not, but I don't know if that is any better? Presence detection that will only detect close objects is sadly out of the question since I want to abort closing the door if a kid runs under it for instance. So it needs to be able to detect the whole width of the opening.
No way to just affix a blinder (think racehorse blinker/blinder) to the sensor to block the sunlight from hitting the sensor? Like, the beam travels in a narrow, straight line to the retroreflector and back again, doesn't it?
I second @hallowed31. I had a similar problem and put a tube in front of the sensor. About 6" long and a couple of inches in diameter. It took a little to get it adjusted but it has worked fine for years.
Thanks for answering! I actually added a tube, but it has not been a success. But I am starting to think the reason for that is that I currently only have room for barely 2 inches. To be able to fit more I would need to move the sensor. It's doable.
But will the retroreflector also potentially get saturated by sunlight? Would I need to shade that too? Or is the sensor enough?
If the narrowed view of the detector looks at a sunlit patch, it will see IR.
Suppose you check many angles 1 at a time where the unblocked view is inside of a box or tube that shades ambient light? Something across the doorway and maybe outside detector as well as inside?
Also, you could try to sense the car metal by capacitance/metal detector or ultrasonic ping. If it has steel you could set up a strong magnet to make a field and a linear hall sensor magnetic field detector and watch for the difference between no car and anything else since iron will change the field. A digital compass might swing when iron passes over using Earth's field, those are so sensitive.
A tennis ball on a string could affect what holds it and that can be sensed.
I'd go with a combination of sensors and test to avoid closing the door on people as well as cars.
I used a sensor designed for garage doors, it was not expensive. It came prepackaged and only required mounting and electronics. All it does is turn on a LED strip when blocked so we can see if the door is clear. When moving into the garage I need to add about 2" after the light goes out because of the bracing on the door.
I think I will try moving it further back, adding a longer tube, getting a larger retroreflector for easier aim and boxing in that retroreflector to shade it as much as possible.
If that doesn't work I'll have to think of something else
I've managed to move the sensor and add a longer tube. The only problem now is that just a few mm of movement on the laser is equivalent to several centimeters on the other side of the wall. It sits fine now, but since our climate changes throughout the year from up to 30 °C with 90% relative humidity down to -25 °C with down to 50 % relative humidity, I am guaranteed to get some movement.
I'll therefore also buy a larger retroreflector, and I should be all set
When you narrow the view of the detector you don't need a laser any more! An IR led will illuminate an area and the detector(s) pick up reflected IR. You can add detector(s) behind where the car or whatever should be if illuminated from the side and get beam-break detection to complement the IR reflect detection.
Lasers concentrate light into a line. Whether you can see it or not, enough photons (depends on strength and frequency) can wreck a retina which is chemical. You don't need laser(s) for this, just dark and light to detector(s).
