Hey guys. I have a general conceptual project question that I was hoping someone would be able to help me with.
I want to be able to detect exactly when a specific person goes through a doorway with fairly low latency. The person would probably carry some kind of identification trigger, and then use the person’s identifying information (a simple code would suffice) to initiate a custom task. What technology would be the best approach for this?
I initially thought about using rfid, but the passive readers have such poor range that I couldn’t mock up a system that would get enough detection in the doorway when the person just carried a tag.
I also thought about a bluetooth setup, since most people have phones which they can use to broadcast their mac address. The problem here is that bluetooth is kind of omnidirectional, and my initial tests usually end up triggering the read too early or too late.
Does anyone have any ideas on the best approach, or maybe some ideas on how to fix the problems with my first two ideas.
Thanks.
Could you use a webcam (or 2, one for each direction) and facial recognition software ?
Theft loss and inventory control systems in stores use electronic tags and a gate to walk through. Would this technology be appropriate?
Give people various doses of radiation and use a geiger counter?
Shave everyones head and apply a bar code tatto to the scalp?
Security officer at a company I worked for wanted to have all employees get one of those id modules they put into pets. Not sure what the range of those are. (Want to guess how well that went over?) Rather than under the skin you could put them into a key-fob.
Perhaps a unique modulated IR becon and a directional reciever in the door way?
Magnets in shoes?
is there door on the doorway or just a open frame?
Is the person passing through required to cooperate with this for it to work?
Lot’s of doors have solenoid latches activated by punching pin numbers in on a key pad that’s hooked up to a PC with cameras, timeclocks, remote overrides etc.
another-dave:
is there door on the doorway or just a open frame?
Is the person passing through required to cooperate with this for it to work?
Lot’s of doors have solenoid latches activated by punching pin numbers in on a key pad that’s hooked up to a PC with cameras, timeclocks, remote overrides etc.
There’s not necessarily a door, just an open frame. The person passing through the door is required to cooperate in the sense that they would be willing to carry some form of electronic signaling device, say in their pocket and the person’s goal would be to trigger the entry detection system through proximity, which would then electronically trigger an event when that person entered the room.
What I’d like is for this to happen passively, so that the person doesn’t have to enter a code or pull out an RFID tag and swipe it.
if it’s just a frame, then you can’t stop people from traveling thru it. So just put a small CCTV system on a inexpensive security DVR with motion detection single frame capture on it. You can’t rely on all travelers having a blue tooth device of appropriate strength or RFID swipe cooperation for an open frame.
another-dave:
if it’s just a frame, then you can’t stop people from traveling thru it. So just put a small CCTV system on a inexpensive security DVR with motion detection single frame capture on it. You can’t rely on all travelers having a blue tooth device of appropriate strength or RFID swipe cooperation for an open frame.
I think I may have written the question in a confusing way. I don't need to stop anyone from entering. What I need is something that will, with the full cooperation of the person, log a particular person as having entered the room through the doorway without him/her having to take any direct physical action.
I don’t need to detect everyone, just those people who want to be part of the system such that they can initiate an action upon entering the room without having to do anything else.
fll-freak:
Theft loss and inventory control systems in stores use electronic tags and a gate to walk through. Would this technology be appropriate?
@ WGN : I think your question was worded appropriately and I'd think the response above is an appropriate answer.
The stop-loss tags that are little white stickons that will activate door sensors don’t have a specific ID like a RFID cards do; but have ‘good’ range. So they can’t log a specific person. Inexpensive RFID tags don’t have good range but give specific ID. So they can log a specific person but require the ‘direct physical action’ of getting the RFID chip within range of the reader. So neither seems to satisfy your requirements as I understand them. As I now understand your need from your latest description, you don’t want to log people but enable an activity based on the user carrying a enabling key. If there are no multiple levels of activities defined by specific user keys, just have a key / don’t have a key you can use the stop-loss type tag system.
I think the RF tags are just a resonant circuit (low Mhz range). If one were to tune each slightly differently and have the exciter sweep/step across a small frequency range, the system could be made to discriminate amongst different users. The question would be how far the OP wants to go in making such a system and how many different users need to be ID’ed … or, perhaps, there are classes of users that need to be ID’ed … vs tagging each individually.
Here’s a (perhaps bizarre) idea. Get those simple 125Khz RFID chips that are embedded in a button / key chain fob rather than a card. Attach them to your shoe laces, a velcro strip on shoes, etc. and put a reader under a tile in the floor that’s colored /marked different than the others. Have users walk across that tile to validate their access to operations others don’t have and log who and when on a PC. You read it here first.
off topic-re: resonant tank method, how many different ID’s do you anticipate needing?
Several years ago I read about a guy building a system to let his cat in. As the cat neared the door his system took a photo. By the time the cat got to the door, the system had determined if it was his cat or not, and if it was, to unlock the door.
Was thinking it might help to break the identification and the entry down into different steps. Maybe read an rfid tag further away from the door frame and then an IR tripwire to see when they actually enter.
Chanler:
Several years ago I read about a guy building a system to let his cat in. As the cat neared the door his system took a photo. By the time the cat got to the door, the system had determined if it was his cat or not, and if it was, to unlock the door.
Was thinking it might help to break the identification and the entry down into different steps. Maybe read an rfid tag further away from the door frame and then an IR tripwire to see when they actually enter.
sounds overly complex (visual recognition). Back to RFID. What’s the upside of reading RFID further away then unlatching with a dumb sensor closer in? you still have to get the RFID in proximity of the reader which is the problem; not the time it takes to read it. If anything, I’d reverse it. With a dumb sensor triggering an RFID transponder when you get within a certain distance from the access point. No point Spewing out RF if it’s not needed. but you still have to get the RFID close to the transponder
OT-That (pet door) is an excellent candidate for the application of simple resonant tank (stop-loss tag) detection.
-No batteries on the tag, infinite life (for tag, not pet).
-Clearly defined access point to scan for tag
-Simple task, have tag at access point, door unlocks. No tag, stays locked. Sorry Mr. raccoon, neighbors dog, scrawny crackhead burglar etc.
another-dave:
sounds overly complex (visual recognition). Back to RFID. What’s the upside of reading RFID further away then unlatching with a dumb sensor closer in? you still have to get the RFID in proximity of the reader which is the problem; not the time it takes to read it. If anything, I’d reverse it. With a dumb sensor triggering an RFID transponder when you get within a certain distance from the access point. No point Spewing out RF if it’s not needed. but you still have to get the RFID close to the transponder
OT-That (pet door) is an excellent candidate for the application of simple resonant tank (stop-loss tag) detection.
-No batteries on the tag, infinite life (for tag, not pet).
-Clearly defined access point to scan for tag
-Simple task, have tag at access point, door unlocks. No tag, stays locked. Sorry Mr. raccoon, neighbors dog, scrawny crackhead burglar etc.
I agree it’s complex to implement, but it should also be the easiest to use as you won’t have to remember to bring anything and it won’t trigger if you’re on the other side of the door frame. That issue was also my reason for thinking out loud of moving the RFID reader further out.
At the expense of batteries and needing to wear or display it, you could do something like an RFID tag with led’s that could also solve the false triggering. Make a fob of sorts that picks up a pattern from the doorway and responds with its own led. A different response pattern in each fob would allow for individual identification.
I guess it depends on how much effort is expected from the person entering the room. Something less than stopping to swipe a card is my interpretation. What about holding something up or maybe displaying a QR or bar code from a cell phone?
my impression was that ‘WildGunman’ didn’t want the user involvement to be any more than have an IDing device on their person.
another-dave:
my impression was that ‘WildGunman’ didn’t want the user involvement to be any more than have an IDing device on their person.
So tattoing a barcode on their forehead is right out !
I like the idea of using something like a beam interrupter triggering an RFID read. I’m still not sure that some sort visual recognition is too hard. It’s mostly SW and perhaps that’s not the OPs specialty.
Mee_n_Mac:
another-dave:
my impression was that ‘WildGunman’ didn’t want the user involvement to be any more than have an IDing device on their person
So tattoing a barcode on their forehead is right out !
did you mean ‘is out, right’? actually, that’s the level of involvement requested, you’re carrying an identifier but it’s up the ‘system’ to know that and do something with it.
I like the idea of using something like a beam interrupter triggering an RFID read.
RFID doesn’t need to be triggered (by a ‘beam interrupter’). It’s a transponder that squirts RF; that RF is used to power up the RFID card which then transmits a code back. But it’s range is measured in inches. So it either has to be be placed by user involvement (bzzzzt! wrong answer) or placed on a shoe. SFE did a tutorial on RFID people should read
I’m still not sure that some sort visual recognition is too hard. It’s mostly SW and perhaps that’s not the OPs specialty.
simple enough to identify a person (shape) or complex enough for a specific person? If just any person willing to be ID’d for access, I’d chose resonant tank tag for the simplicity. But as I understand it he want to log who also
‘WildGunman’- how many volunteer victims do you anticipate?
another-dave:
Mee_n_Mac:
So tattoing a barcode on their forehead is right out !
**did you mean 'is out, right'? actually, that's the level of involvement requested, you're carrying an identifier but it's up the 'system' to know that and do something with it.**
Actually I meant '"right out" but I suppose not everyone is a Monty Python fan. :mrgreen:
another-dave:
Mee_n_Mac:
I like the idea of using something like a beam interrupter triggering an RFID read.
**RFID doesn't need to be triggered (by a 'beam interrupter'). It's a transponder that squirts RF; that RF is used to power up the RFID card which then transmits a code back. But it's range is measured in inches. So it either has to be be placed by user involvement (bzzzzt! wrong answer) or placed on a shoe. SFE did a tutorial on RFID people should read**
No it doesn't need to be but here was my thinking. Any system which could read an RFID tag at a distance (and that can be done) might want to distinguish between someone crossing the threshold and someone outside of the doorway. A beam triggered system helps in that regard.
another-dave:
Mee_n_Mac:
I’m still not sure that some sort visual recognition is too hard. It’s mostly SW and perhaps that’s not the OPs specialty.
**simple enough to identify a person (shape) or complex enough for a specific person? If just any person willing to be ID'd for access, I'd chose resonant tank tag for the simplicity. But as I understand it he want to log who also**
‘WildGunman’- how many volunteer victims do you anticipate?
I'll see if I can't dig up the video I saw a bit ago on HaD. The grad student had a facial recognition system running on simple HW using Matlab and with a webcam. Given co-operative victims this might be one way of accomplishing the task.
Any system which could read an RFID tag at a distance (and that can be done) might want to distinguish between someone crossing the threshold and someone outside of the doorway. A beam triggered system helps in that regard.
what system are you referring to? I’ve worked in the commercial RFid engineering business and all the 125Khz and 13.56Mhz passive systems I’ve seen have ranges of about 2"
while I haven’t worked with them, The only ‘long range’ systems I’m aware of are the powered / active kind. About the size of a pack of cigarettes. Such as EZpass and they are not available for private use or in small quantities
Nike has a passive, shoe based system for minimal user cooperation in foot races, so I guess I didn’t think it up for the first time in my posting last week 
another-dave:
Any system which could read an RFID tag at a distance (and that can be done) might want to distinguish between someone crossing the threshold and someone outside of the doorway. A beam triggered system helps in that regard.
what system are you referring to? I’ve worked in the commercial RFid engineering business and all the 125Khz and 13.56Mhz passive systems I’ve seen have ranges of about 2"
while I haven’t worked with them, The only ‘long range’ systems I’m aware of are the powered / active kind. About the size of a pack of cigarettes. Such as EZpass and they are not available for private use or in small quantities
Nike has a passive, shoe based system for minimal user cooperation in foot races, so I guess I didn’t think it up for the first time in my posting last week
Active transponders are what I’m thinking of. I don’t think they need to be as bulky as EZ Pass.