I want to replace the standard obstruction detectors, IR, with object detectors
I cannot find content for this project.
Using a thermal camera, I use image comparison to detect motion. If image motion is detected, then send image to a RPi where I use TensorFlow Lite to detect objects and determine between live objects and nonliving things. When a live thing is detected, I further process the image using KNN (Nearest Known Neighbour) to determine if the live thing is a human or animal. If human do some other things.
What is an object? I do not ask as a joke but in all seriousness, what is an object?
Example it is easy to take a full color image, down scale it, and compare it to the last image. If X number of images show changes, then do things. I can get about 5 or so images per second processed to do image comparison using a ESP32 and a ESP32CAM.
I've been working with the Adafruit Weatherproof TTL cam, Weatherproof TTL Serial JPEG Camera with NTSC Video and IR LEDs : ID 613 : $54.95 : Adafruit Industries, Unique & fun DIY electronics and kits. Going has been slow, I am writing my own library using the ESP32's Serial API. I really like the cameras night vision capibilities.
My plan is to have the camera do the work of image comparison and upon movement detection then send a trigger to the ESP32 to process. That way I can get rid of the ESP32CAM and use only 1 ESP32 that will do the image processing, lowering my power requirements. The project runs on solar.
TensorFlow is better ran on a RPi.
KNN runs well on a 32 bit MCU.
Simple machine learning with Arduino KNN | Arduino Blog
The example is very simple and only touches on the possibilities of KNN on a 32bit MCU.
What's the problem you're trying to solve?
So if you're standing still the door can come-down on you? 
PIR motion detectors are "Passive Infra Red" and the detect body heat. They won't detect an object that's the same temperature as it's surroundings. And any kind of "simple" device that simply detects movement is probably going to "detect" movement of the door.
I want to detect an object within the path of the door closing. The area is approximately 16’ X by 10’ Y. With is about 1’. The reason is if you put a ladder in the door closing path, it will not be detected by the present transmit/receive technology.
You could try to implement a light curtain with a row of lasers or maybe carefully focused LEDs.
To detect obstructions, it would be pretty straightforward to use a camera. The ESP32-CAM module is self contained, communicates with WiFi if you wish and costs less than $10.
It could be set up to compare a reference image of the door open with no obstructions, to a new image. Significant changes from the reference image could be an alarm situation.
Jeez!!!
The fact that you can get any kind of camera, no matter how bad the resolution, for under $10 just blows my mind!
I have all that information, thanks,
The part I don’t have is how to replace the the current system that is attached to the garage door opener controller. The signals the current obstruction sensor use are a mystery to me. The signals are pulsed at a specific rate so I need to duplicate that as an on / Off flag.
Complete mystery to us, too. Good luck with your project!
I don't know if they all work like this but ISTR that on my garage door, the signal pulsing is used to reject ambient light hitting the sensor. I vaguely remember looking at it about 15 years ago.
Your post was MOVED to its current location as it is more suitable
To be on the safe side (and to not violate any safety regulations if you live in the US or other country with applicable laws), your system should not replace, but should be in addition to the obstruction detector that came with the door.
Residential garage doors in the US...
...must comply with the above, which cites ANSI/DASMA 102 and certain UL standards.
This is not legal advice. You are working at your own risk.
Ditto.
A modulated light beam used to filter sunlight etc from randomly triggering the sensor.
Also used in optical card readers installed in areas with high ambient sunlight.
OK. Thank you all.
Actually, they detect heat that moves within the allocated "zones".
A stationary object regardless of heat output can go undetected.
Not difficult to proove, just stand stationary in front of a pir.
This might be of interest:
https://pages.mtu.edu/~suits/electronics/GarageElecEye.html
You can also do it with a microprocessor easily. I can’t find it just now, but it’s a simple pulse generator running an IR LED, just uses delay or delayMicroseconds to make the required frequency and duty cycle.
HTH
a7
A ladder will obviously not be detected by a motion sensor, or PIR. 
Thank you. This is the solution I am looking for.
It is the interface logic I am missing.
I saw articles about this interface but no hard solution.
After I find the interface logic, I can make a final determination of the sensor.
Could do the same with a $2 ultrasonic module.
I have used the door sensors in other projects. I simply monitor the current. It is a pulsing current but it is easy to monitor. If you put a switch,relay, etc in series with the signal opening it will trip the alarm circuit.