I know I will find thousands of smart people here, I'm looking for help to solve a problem.
I have a door between rooms. I need to somehow open this door if the person wanting to pass is within 3-8 meters. I have written up to 10 in the subject line, but it is not that important. The important thing is that the door only works if that person has authorisation to cross, so proximity sensors are out.
I was considering some sort of communication between the ESP8266, but the issue of constantly powering a device that someone has in their pocket, and recognising the distance between two ESPs is probably hard to figure out.
A person can approach from both sides of the door, so the signal will be weaker from one side, or you have to mount receivers on both sides.
At the door I have a 24V power supply that I can turn into any lower one, this is not a problem.
The devices in the pocket / hanging around the neck of the person entering must be battery powered and last a minimum of 16 h of operation without charging (I can use 18650 and charge overnight).
The ideal solution is some type of RFID card, but communication over such a distance is expensive and I am looking for a cost-effective solution.
Please give me ideas on what I can use, all things considered.
BaGRoS
Also, I don't need 10 cm accuracy, 5 meters is more than enough. Door should be open when somebody with "device" is 3-8 m, so accuracy like 5 m is enough. I do not need any authorization if door could be open only by the "device".
Thank you for the suggestion, I can dig deeper.
BaGRoS
I used to work in the access control industry and this was sometimes asked for by customers. However it is not very safe.
Supposed some unauthorised person wants to get in. All they have to do is to hangout close to the door and wait until someone with a token to walk past the door but not in. He will here the door unlocked and then he can go to the door and go through it just like he had authorised access.
We always explained this case to customers who asked for this feature, and they always changed there minds about wanting it.
If you can guarantee that the person will be wearing the device in a specific location, e.g., around the neck and they have to face the door to open it, then any BLE device, even a BLE beacon could be used. Just trigger the door when the beacon signal is seen at a high enough RSSI.
The reason they need to face the door is that the signal strength will drop considerably if their body is in the path between receiver and transmitter.
This is for PPT drivers, so if they are the only ones going to the door, it should open, the production people should not open it. That's why a motion sensor, proximity sensor, microwave sensor will not work.
What about using the facial recognition feature of the ESP32-CAM? I wouldn't use it for access to a nuclear power station... but for the type of thing you are talking about it should work ok.
Of course, close to the door we have a fob reader (outside) or button (inside), so everyone can walk and open the door. But this is time, time is money... They open this door every few minutes, so by 12h is a lot, time and walking.
No space.
This is packhouse, so a lot of machinery around, driving by the door both directions, time to time by two doors in matter of seconds, from packhouse to 1st chiller and second door 8 m from 1st, by second door to second chiller.
So now that we actually know how this is going to be used (would have been nice if you'd said that upfront!), is there a reason you can't have a "normal" remote access panel in the forktruck that the driver can enter a code on as they approach the door? Solve the distance problem and the authorization problem in one swoop!
Now we have remote controls, they fall out of their hands, they are broken, they create a danger when driving. The company that makes them does so at the exclusivity of the door manufacturer, which I cannot contact. I can of course replace all the control panels, and all the remotes. However, if it is possible to use, for example, ESP8266s as servers and measure distances to clients, which could also be ESP8266s then it is worth a try. The point is that then they don't have to look for a button (each one is for a different door) and thus get distracted from driving.
Yes, Should be ok. Can I read by ESP32? How much can I read at the same time, because you know, they will be moving around, then even some weak signals will overlap.
this solution is cheap enough that I can even stick two beacons to each truck on two sides and have confirmation from both that it is coming.
EDIT: I need LOW LATENCY device, which can send data with frequency 10Hz.
You will read every signal that is in range. That could be 1 or 100. In a large building it will probably be hundreds. You'll have to filter by name and signal strength.
10Hz is on the limit of BLE advertising frequency. IIRC it can be set as low as 100ms, but it's been a while, so I could be wrong. After all, the "LE" means Low Energy so the rate isn't very fast.
You could use a phone, yes. Or a much lower cost and lower power BLE tag. Again, placement is very important. If you use a phone in someone's back pocket you will get a much weaker signal than if it's mounted on the front of the fork truck. This will render filtering by signal strength useless.
