I have recently seen the circuit diagram of an interesting concept in the page - Bidirectional Visitor Counter using Microcontroller.

I am planning to do this project circuit on next week with few modifications. If we arrange this circuit to a particular large room for any meeting, it helps to count the people entering or leaving the room. But, here if the same person enters and leaves the room for more than once, it adds that many number of +1's to the total count. As a result, I think it is not possible to get exact total count of the different people that enter the room.

So, my requirement is that it should count only when a new person enters or leaves the room. i.e. if the person enters or leaves the room for more than once, it should identify it and treat it as only 1. As a result we may get correct number of different people entered or left the room. I think you understood about my requirement.

So, are there any other devices have to be added to this circuit? I have already asked my friends about this, but no one has given the solution. So, Can anybody kindly suggest me the required modifications to be done in this circuit?

  • 3
    \$\begingroup\$ Could you just subtract one when they leave and use the maximum to get an idea of how many were at the meeting? That way it won't matter if they come and go a few times during it. Otherwise you'd need them to have something like an RFID tag or use something like facial recognition which would be a lot more involved. \$\endgroup\$ – PeterJ May 7 '14 at 6:54
  • \$\begingroup\$ Yeah, this is more of an administrative problem than electronics: how do you identify the "same person"? \$\endgroup\$ – pjc50 May 8 '14 at 12:41
  • \$\begingroup\$ I mean, by arranging some biometric face recognition system. If the same person comes more than one time, it treats as duplicate and it never counts that person again. Is it not possible to arrange such type of instrument in the circuit shown in the link? \$\endgroup\$ – user3580208 May 9 '14 at 6:07

This is super easy to do. All you need is a digital input that goes high when a new person is detected, and is low when an already detected person is detected again. From an electronics perspective, it's easy. I see PIB2 is open on the micro, so why not use this? A little fiddling with the code to change the logic, and you're good to go.

The difficulty is, how do you recognize a person? Biometrics is an active research field. Facial recognition is possible, and we're starting to see relatively accurate results from new implementations. If you were to go this route, I don't think a microprocessor's going to cut it, anymore. I'd recommend a mid-grade computer controlling a camera to take a picture of each person who enters the room. A good starting point for getting facial recognition working is OpenCV. I'll gloss over the details since there's a number of algorithms to do it, but in the end, all you need is that digital out running to PIB2, and you're gravy.


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