Pedestrian crossing human-detector

The IR LEDs were probably sending out known pulse sequences. If they want security then make them pseudo random. But probably not on something like this. Then on the receiving end the microcontroller verifies it's getting the expected pulse sequence. If it is, then it knows it has good data for detection. If not it can ignore it.

Nani Isobel

Yeah, today a cheap camera would be used. I suspect that is older, pre-camera hardware. Modern digital video compression algorithms include motion detection. Once the algorithms were implemented in hardware, camera based motion detection got really cheap.

Nani Isobel

The British pedestrian crossings come in several flavours, which are officially given names like pelican, puffin, toucan, etc. My favourite is the Toucan, which is for both pedestrians and cyclist. Two can cross. Two can. Toucan... geddit?

Jon Knight

Today, the cost of a low resolution camera is insignificant, but then the video needs to be processed by software to analyze the humans in the scene and interpret that into reliable control signals - we wouldn't want someone to get in an accident. I'm surprised that the IR LEDs don't show up brightly in the camera's sensors.

John Lundgren ~ Acme Fixer

I suppose that makes sense. A photo Diode is presumably sensitive to more than just ambient light. RThanks all.

Mike Hughes

Ha ha! Yes our light controlled pedestrian crossings were/are named after birds, pelican, puffin & toucan. The puffin replaced the pelican crossing and has different traffic light sequence. The Toucan has lights for cyclists to cross and now we also have Pagasus crossings which allow horses (with or without a mounted rider) to cross. And as Clive rightly says Zebra crossings where pedestrians have right of way as soon as they set foot on the black and white striped crossings. The only warning lights there are Belisha Beacons....orange flashing balls on a black and white pole now replaced by LED disks. And in London and some other major cities there are count down displays on their toucan crossings allowing suicidal pedestrians to know how long they've got to live before being mowed down by a courier cyclist or black cab as they race to cross the road before the lights change lol

And zebra crossings too. I think they give then cute names to encourage kids to use them.

Big Clive

"Keystone" correction, he noted Amazing to me that they are so precisely aimed.

Peter Laws

"...older pelican crossings and the newer toucan and puffin crossings..." I know each of those words, but I cannot make this sentence make sense. This must be a British thing?

Circuitmike

The PCB is marked PDx (where x = some number) so I assume photodiodes.

Circuitmike

I knew about the rotating cone underneath. First spotted it when I saw a vandalised button box and wondered why there was a motor. During covid they also added some contactless activation by means of an IR unit underneath.

Big Clive

It does look the part.

Big Clive

Ah, I didn't spot the ADC. I had a brief glance at the 16C66 and didn't immediately see an ADC. I used to use the Zetex ZTX300 in my microtransmitters.

Big Clive

I'd guess photodiode.

Big Clive

Plessy controls on someToucan and Pegasus crossings use similar to monitor the crossing and waiting point after a request to cross is made by a pedestrian. They monitor whether a pedestrian has cleared the crossing and edjust the light timing as appropriate. Some can rudimentarly count how many people are waiting to cross and also time the crossing period. As an aside did you know the push to cross button box with the Wait sign on older pelican crossings and the newer toucan and puffin crossings have a spinning grooved cone underneath so blind/deaf blind or partially sighted pedestrians know by feel when the cone spins it's safe to cross. (I briefly worked for a company that supplied Plessy with boards for inductive sensors embedded in the road at traffic lights)

Clive mentions this. It appears to be so they can cover the road / pavement surface evenly.

Mike Page

The positions of the LEDs is strange. I would have expected an even layout.

evilution

It might make a good head/scanner for a battle robot. Human detected. EXTERMINATE. :D

David Ihnen

Neat. Those Zetex E-Lines date it along with the 16C66, which is OTP. At least it has ICSP so you can make do with a half dozen windowed parts for development - or a quite expensive emulator. I am slow. Just realized IC1 is LTC1286 12 bit ADC. That's more like it. The 16C66 has no ADC.

Mike Page

I thought these looked at the crossing area, rather than the waiting area, so I assumed they were looking for people actually crossing so they could adjust the traffic red light time to suit. I’ll have to have a conscious look at one the next time I’m passing

Adam Pepper

What type of sensor is it? (I realise it's Infra Red, but is it like an LDR or more of a photo diode? just curious.)

Mike Hughes

Pretty cool device. Would love to play with one.

Derek Smith