Post by thread:[EE] Vehicle detection

PICers, I have a possible(?) project coming up that involves vehicle detection/counting. Pessure mats, wire loops etc not an option. The gizmo needs to be small, & portable - the requirement is to count cars as they enter/leave a large outdoors *BIG* temporary car park. The cars will come down a narrow track marked out with poles/flags, so the sensor can be positioned pretty close as they pass buy. digging up the grass for cables etc - No No. I was thinking maybe of Honeywell's detectors. To wit, one of these ---> http://www.ssec.honeywell.com/magnetic/mark_det.html Has anyone used them? Are they OK? Are there better/cheaper devices around? Thanks for advice - Debbie ____________________________________________________ Do you Yahoo!? Join the Girlfriend magazine VIP Club for insider info, freebies and more http://www.girlfriend.com.au/

I would suggest to use a desktop computer and a camera, it would be chip and you will avoid developing it, if it's a one time project. I have a software to do the task, it can use, for example a cheap ip camera. It's intended for other purposes, but can be modified to identify moving cars and count them. Regards, Mauricio Jancic Janso Desarrollos http://www.janso.com.ar spam_OUTinfoTakeThisOuTjanso.com.ar (54) 11-4542-3519 > {Original Message removed}

How narrow is the track? You could potentially use laser or IR if you can position the vehicles such that only one goes through at a time (laser or IR) and/or the track is narrow enough to get the sensor (IR) close to the vehicle) On 10/11/06, Debbie <.....cyberia429-piclistKILLspam@spam@yahoo.com.au> wrote: {Quote hidden}> > PICers, > I have a possible(?) project coming up that involves vehicle > detection/counting. Pessure mats, wire loops etc not an option. The gizmo > needs > to be small, & portable - the requirement is to count cars as they > enter/leave > a large outdoors *BIG* temporary car park. The cars will come down a > narrow > track marked out with poles/flags, so the sensor can be positioned pretty > close > as they pass buy. digging up the grass for cables etc - No No. > > I was thinking maybe of Honeywell's detectors. To wit, one of these ---> > > http://www.ssec.honeywell.com/magnetic/mark_det.html > > Has anyone used them? Are they OK? Are there better/cheaper devices > around? > > Thanks for advice - Debbie > > > > > ____________________________________________________ > Do you Yahoo!? > Join the Girlfriend magazine VIP Club for insider info, freebies and more > http://www.girlfriend.com.au/ > -

Well, if you're going to do that then you could write a small filtering program in Matlab. We wrote an application to count the amount of change in a picture taken with one of those small Agilent CMOS cameras you see in all of the phones now. Fun project, and not terribly difficult either. But I still think some sort of laser sight would work the best. Every time the line is broken, you have a vehicle in the "trap". On 10/11/06, Mauricio Jancic <infoKILLspamjanso.com.ar> wrote: {Quote hidden}> > I would suggest to use a desktop computer and a camera, it would be chip > and > you will avoid developing it, if it's a one time project. I have a > software > to do the task, it can use, for example a cheap ip camera. It's intended > for > other purposes, but can be modified to identify moving cars and count > them. > > Regards, > > Mauricio Jancic > Janso Desarrollos > http://www.janso.com.ar > .....infoKILLspam.....janso.com.ar > (54) 11-4542-3519 > > > > {Original Message removed}

> PICers, > I have a possible(?) project coming up that involves vehicle > detection/counting. Pessure mats, wire loops etc not an option. > The gizmo needs > to be small, & portable - the requirement is to count cars as > they enter/leave > a large outdoors *BIG* temporary car park. The cars will come > down a narrow > track marked out with poles/flags, so the sensor can be > positioned pretty close > as they pass buy. digging up the grass for cables etc - No No. what are you using theese counts for? do in cars and out cars take different routes? what accuracy do you need (e.g. what proportion of counts can you afford to gain/lose before the data becomes useless to you)

--- peter green <EraseMEplugwashspam_OUTTakeThisOuTP10Link.net> wrote: > what are you using theese counts for? Sounds like they want to check up on ticket sales vs cars in/cars out. > do in cars and out cars take different routes? Yep. > > what accuracy do you need (e.g. what proportion of counts can you afford to > gain/lose before the data becomes useless to you) Basically, want to log all cars. The vehicles will be pretty close to the sensor and slow moving (<15 k/h) so should give big magnetic sig? Path width should be, say, <5metres. It's a sports event - as the car park fills up, they move the poles, path and traffic wardens someplace else. Ditto car counter. So you probly don't want a gizmo that needs turf dug up or dangles loops or is fiddly to align. I'm thinking magnetic would be the way to go? Those Honeywell sensors have analogue o/p but that wouldn't be a big drama. Thanks -Debbie ____________________________________________________ On Yahoo!7 Answers: Share what you know and you might make someone's day http://www.yahoo7.com.au/answers

Do they need to detect motorbikes / bicycles / golfcarts etc.. RP On 12/10/06, Debbie <cyberia429-piclistspam_OUTyahoo.com.au> wrote: {Quote hidden}> --- peter green <@spam@plugwashKILLspamP10Link.net> wrote: > > > what are you using theese counts for? > > Sounds like they want to check up on ticket sales vs cars in/cars out. > > > do in cars and out cars take different routes? > > Yep. > > > > > what accuracy do you need (e.g. what proportion of counts can you afford to > > gain/lose before the data becomes useless to you) > > Basically, want to log all cars. The vehicles will be pretty close to the > sensor and slow moving (<15 k/h) so should give big magnetic sig? Path width > should be, say, <5metres. It's a sports event - as the car park fills up, they > move the poles, path and traffic wardens someplace else. Ditto car counter. So > you probly don't want a gizmo that needs turf dug up or dangles loops or is > fiddly to align. I'm thinking magnetic would be the way to go? Those Honeywell > sensors have analogue o/p but that wouldn't be a big drama. > Thanks -Debbie > > > > ____________________________________________________ > On Yahoo!7 > Answers: Share what you know and you might make someone's day > http://www.yahoo7.com.au/answers > -

Debbie wrote: {Quote hidden}> --- peter green <KILLspamplugwashKILLspamP10Link.net> wrote: > > >> what are you using theese counts for? >> > > Sounds like they want to check up on ticket sales vs cars in/cars out. > > >> do in cars and out cars take different routes? >> > > Yep. > > >> what accuracy do you need (e.g. what proportion of counts can you afford to >> gain/lose before the data becomes useless to you) >> > > Basically, want to log all cars. The vehicles will be pretty close to the > sensor and slow moving (<15 k/h) so should give big magnetic sig? Path width > should be, say, <5metres. It's a sports event - as the car park fills up, they > move the poles, path and traffic wardens someplace else. Ditto car counter. So > you probly don't want a gizmo that needs turf dug up or dangles loops or is > fiddly to align. I'm thinking magnetic would be the way to go? Those Honeywell > sensors have analogue o/p but that wouldn't be a big drama. > Thanks -Debbie > > > > ____________________________________________________ > On Yahoo!7 > Answers: Share what you know and you might make someone's day > http://www.yahoo7.com.au/answers > The system I was familiar with used a loop buried in the concrete. The loop (plus the concrete) formed a tuned circuit. When a car drove over it, it detuned it because of the metal of the car. It was rugged and durable. Very easy to design, too, and insensitive to people and small objects over it. About 2m in diameter, buried about 4" deep. About 100 turns of #24 magnet wire. Very similar to the familiar "metal detector" design, where a loop of wire, covered with a lead foil shield, was embedded into a plastic wheel. You have to have the shield to stop capacitive (leaving only the inductive) effects. These are used in airport parking lots to dispense a ticket when a car drives up, as well as to verify that the car has left the dispenser. --Bob

> Very similar to the familiar "metal detector" design The detector doesn't have to go in the ground. It can sit on top, perhaps under a plank, which would also be the spacing for the poles, so the whole thing could be moved intact from point to point Silicon Chip had this as a project a couple of years ago http://www.siliconchip.com.au/cms/A_102998/article.html Available as kit KC5402 from http://www.jaycar.com.au

> So you probly don't want a gizmo that needs turf dug up or > dangles loops or is fiddly to align IMHonestO, a laser is the least problematic solution. It won't get dirty, is cheap, reliable, and not really that much of a chore to set up. The beam is quite plainly visible on the target so it's easily aligned. The detection process is very simple. Although people will be sensed, their passage across the beam is of much shorter duration than a vehicle and can be ignored / filtered out If the beam can also be modulated, that makes it (almost) totally immune to ambient perturbations, especially with a specific colour filter over the target sensor

--- Jinx <RemoveMEjoecolquittTakeThisOuTclear.net.nz> wrote: > Silicon Chip had this as a project a couple of years ago > > www.siliconchip.com.au/cms/A_102998/article.html > > Available as kit KC5402 from http://www.jaycar.com.au Hey, goodonya Jinx!!!! That article sounds //very// much like what I was thinking of. RP asks: golf carts, m'bikes? No, don't think they're of concern. Thanks guys. Ideas ..... Debbie :) ____________________________________________________ On Yahoo!7 Answers: Share what you know and you might make someone's day http://www.yahoo7.com.au/answers

Jinx <joecolquitt <at> clear.net.nz> writes: > > > So you probly don't want a gizmo that needs turf dug up or > > dangles loops or is fiddly to align > > IMHonestO, a laser is the least problematic solution. It won't > get dirty, is cheap, reliable, and not really that much of a chore > to set up. The beam is quite plainly visible on the target so it's > easily aligned. The detection process is very simple. Although > people will be sensed, their passage across the beam is of much > shorter duration than a vehicle and can be ignored / filtered out > > If the beam can also be modulated, that makes it (almost) totally > immune to ambient perturbations, especially with a specific colour > filter over the target sensor > Are there any health/legal problems with lasers for such application as parking? Suppose somebody gets drunk at the sporting event and decides to look into the laser? Even 5 mW laser pointer can be bad for eyes. Legal liabilities could be very high. Sergey Dryga

Why not use a standard industrial retro-reflective (IR) sensor with the appropriate reflector? See http://www.banner.com for more info. There are many other manufacturers of these but the Banner mini-beam sensors are great. Regards, Stephen D. Barnes Debbie wrote: {Quote hidden}> PICers, > I have a possible(?) project coming up that involves vehicle > detection/counting. Pessure mats, wire loops etc not an option. The gizmo needs > to be small, & portable - the requirement is to count cars as they enter/leave > a large outdoors *BIG* temporary car park. The cars will come down a narrow > track marked out with poles/flags, so the sensor can be positioned pretty close > as they pass buy. digging up the grass for cables etc - No No. > > I was thinking maybe of Honeywell's detectors. To wit, one of these ---> > > http://www.ssec.honeywell.com/magnetic/mark_det.html > > Has anyone used them? Are they OK? Are there better/cheaper devices around? > > Thanks for advice - Debbie > > > > > ____________________________________________________ > Do you Yahoo!? > Join the Girlfriend magazine VIP Club for insider info, freebies and more > http://www.girlfriend.com.au/ >

> Are there any health/legal problems with lasers for such application > as parking? Suppose somebody gets drunk at the sporting event > and decides to look into the laser? Even 5 mW laser pointer can > be bad for eyes. Legal liabilities could be very high I think you'd have to be *** extremely *** drunk for the blink response not to be working. And I'm sure even someone completely sodden with booze would turn away, if only out of irritation, and stagger off muttering. Anything's possible of course, and there have been some silly PC liability issues in Australia recently

You could go purchase the a garage door opener and use the child detection sensors out of that. If you can't find the sensors elsewhere. On 10/11/06, Stephen D. Barnes <spamBeGonestephendbarnesspamBeGonecox.net> wrote: {Quote hidden}> > Why not use a standard industrial retro-reflective (IR) sensor with the > appropriate reflector? > See http://www.banner.com for more info. There are many other manufacturers of > these but the Banner mini-beam > sensors are great. > > Regards, > Stephen D. Barnes > > Debbie wrote: > > PICers, > > I have a possible(?) project coming up that involves vehicle > > detection/counting. Pessure mats, wire loops etc not an option. The > gizmo needs > > to be small, & portable - the requirement is to count cars as they > enter/leave > > a large outdoors *BIG* temporary car park. The cars will come down a > narrow > > track marked out with poles/flags, so the sensor can be positioned > pretty close > > as they pass buy. digging up the grass for cables etc - No No. > > > > I was thinking maybe of Honeywell's detectors. To wit, one of these ---> > > > > www.ssec.honeywell.com/magnetic/mark_det.html > > > > Has anyone used them? Are they OK? Are there better/cheaper devices > around? > > > > Thanks for advice - Debbie > > > > > > > > > > ____________________________________________________ > > Do you Yahoo!? > > Join the Girlfriend magazine VIP Club for insider info, freebies and > more > > http://www.girlfriend.com.au/ > > > > -

How about something air operated - like the old gas station drive over the hose ding-ding. Maybe you could use a small aquarium pump to generate air pressure and pump the pressure into an open-ended hose stretched across the road. If someone drives over the hose the pressure builds up and trips an air switch - then count the pulses - 1 pulse per axle. Something like this... http://www.metrocount.com/products/roadsideunit/index.html Maybe this is not an option because it's too much like a pressure mat though. -- Mark > {Original Message removed}

Stephen D. Barnes wrote: >Why not use a standard industrial retro-reflective (IR) sensor with the >appropriate reflector? >See http://www.banner.com for more info. There are many other manufacturers of >these but the Banner mini-beam >sensors are great. > This is exactly what I was going to suggest, but OP should note that these will detect anything that breaks the light beam. People, etc. You will also have to align the reflector and sensor every time it is moved. BTW, that link should be http://www.bannerengineering.com. (I am partial to the Mini-Beam SM312.) Aaron

--- Aaron <TakeThisOuTaaron.piclistEraseMEspam_OUTgmail.com> wrote: > Stephen D. Barnes wrote: > >Why not use a standard industrial retro-reflective (IR) sensor with the > > This is exactly what I was going to suggest, but OP should note that > these will detect anything that breaks the light beam. People, etc. > You will also have to align the reflector and sensor every time it is moved. Hey, that's a good point! There'll be lots of people walking about, going to/from cars, there'll be children, couple of kiosks/vendors selling balloons, sausages etc. But it's only cars they want to count. -- Mark Scoville <RemoveMEmscovilleTakeThisOuTunicontrolinc.com> wrote: > How about something air operated - like the old gas station drive over the Yeah, I thought about those pressure hoses. The police(?) put them across roads to monitor traffic. There are two snags with the hose idea, as I see it --> 1/ The ground in the car park (temporary venue) is soft in places. ie grass, sandy soil etc. The wardens will move the flags + detectors etc about and you don't know where, exactly. 2/ You don't want the tube getting snagged in cars' wheels or passersby tripping over it. So @ the mo' .... I'd say I'm leaning very much towards magnetic sensors. I located a copy of that Silicon chip article in a local library, Jinx. Will go dig it out today. Debbie ____________________________________________________ On Yahoo!7 Check back weekly for Trixi's new online adventures http://www.trixi.com.au

On Thu, 12 Oct 2006 01:03:55 +0200, Debbie <cyberia429-piclistEraseME.....yahoo.com.au> wrote: > PICers, > I have a possible(?) project coming up that involves vehicle > detection/counting. [...] Would a capacitive sensor do the job? There should be a sufficient difference in capacitance between people and cars. Using a LMC555 or similar for converting capacitance to frequency, and then counting this frequency with a PIC should be cheap and straightforward. I'm using the same technique for tracking gestures, and it works quite well even with a small human hand. Look at http://thereminvision.com/version-2/TV-II-index.html for a useable circuit design. Using two 20x20 cm electrode plates should provide sufficient range and redundancy. Place one plate on each side of the track - if both show a capacitance change at the same time it's probably a car and not someone standing in front of it. Raphael -- Raphael Wimmer LFE Media Informatics E-Mail: EraseMEraphaelhcilab.org University of Munich WWW: http://hcilab.org Amalienstr. 17 Tel: +49 89 2180-4659 80333 MÃ¼nchen Fax: +49 89 2180-99-4659 Germany

How about a 38 khz signal, being sent as 1 ms pulses; a 3 pin IR detector would easily detect the pulses at the distance you want. Keep polling the pulses; if they are interrupted, you increment the counter. This would also work the other way (the vehicle reflects the signal) if you need the trasnmitter and the detector on the same side. In this case, you'll need to shield them from each other to prevent direct crossover, though. Regards, Anand {Original Message removed}

--- Anand Dhuru <RemoveMEardhuruEraseMEEraseMEvsnl.com> wrote: > How about a 38 khz signal, being sent as 1 ms pulses; a 3 pin IR detector > > Anand > From: "Richard Prosser" <RemoveMErhprosserspam_OUTKILLspamgmail.com> > > > Do they need to detect motorbikes / bicycles / golfcarts etc.. > Hmmm. Looks like it's either an IR sig, modulated @ 38-40kHz, to a reflector and back or a magnetic sensor, Honeywell probly. The reflector set up would work, I'd say, but needs to be aligned + I'm thinking about battery capacity if you're flashing the light non stop all day. The battery wouldn't have to be particularly small, however. The gizmo described in that Si-chip article used a hand wound sensor coil, so not really practical. Basically, it was a metal detector cct like you go after nuggets with. So, OK, I have a few 3-pin IR rx/demodulators ... will do some expts, see how it looks. Thanks for all the tips, guys. Debbie PS: It's mainly cars they want to count. Bikes etc don't pay so not of interest. I think motorbikes do but I'm guessing a big bike like a Harley or top end BMW would probably have a (magnetic) signature like a car anyway. ____________________________________________________ On Yahoo!7 Photos: Unlimited free storage – keep all your photos in one place! http://au.photos.yahoo.com

> The gizmo described in that Si-chip article used a hand- > wound sensor coil, so not really practical. Basically, it was > a metal detector cct like you go after nuggets with As they say in the article, the coil is thousands of fine turns on a soft iron core and impractical to wind youself, so it's supplied ready-made with the kit. The difference between what SC did and a metal detector is that their coil is passive, and relies on the disturbance of the Earth's magnetic field to cause voltage in the coil. They call it a low-power system (70mA, though I can see room for improvement in the circuit) but I've no idea how that compares with a typical metal detector

--- Jinx <RemoveMEjoecolquittTakeThisOuTspamclear.net.nz> wrote: > > As they say in the article, the coil is thousands of fine turns > on a soft iron core and impractical to wind youself, so it's > supplied ready-made with the kit. The difference between > what SC did and a metal detector is that their coil is passive, > and relies on the disturbance of the Earth's magnetic field > to cause voltage in the coil. They call it a low-power system > (70mA, though I can see room for improvement in the circuit) > but I've no idea how that compares with a typical metal > detector Yep, you're right Jinx. :) A metal detector has an oscillator to excite one coil, usually. I built one a ways back. Turned out ants in central Victoria have this habit of piling up tiny iron pellets all over their nests .... :( Debbie ____________________________________________________ On Yahoo!7 Break a world record with Total Girl's World’s Largest Slumber Party http://www.totalgirl.com.au/slumberparty

Debbie, On Mon, 16 Oct 2006 13:48:09 +1000 (EST), Debbie wrote: {Quote hidden}> --- Jinx <EraseMEjoecolquittspamspamBeGoneclear.net.nz> wrote: > > > > As they say in the article, the coil is thousands of fine turns > > on a soft iron core and impractical to wind youself, so it's > > supplied ready-made with the kit. The difference between > > what SC did and a metal detector is that their coil is passive, > > and relies on the disturbance of the Earth's magnetic field > > to cause voltage in the coil. They call it a low-power system > > (70mA, though I can see room for improvement in the circuit) > > but I've no idea how that compares with a typical metal > > detector > > Yep, you're right Jinx. :) A metal detector has an oscillator to excite one > coil, usually. I built one a ways back. Turned out ants in central Victoria > have this habit of piling up tiny iron pellets all over their nests .... :( Perhaps it's a trap? It gets metal detectorists to start digging, then the ants swarm out and eat them! :-) Cheers, Howard Winter St.Albans, England

>Hmmm. Looks like it's either an IR sig, modulated @ 38-40kHz, to a >reflector >and back or a magnetic sensor, Honeywell probly. >The reflector set up would work, I'd say, but needs to be aligned + I'm >thinking about battery capacity if you're flashing the light non stop all >day. >The battery wouldn't have to be particularly small, however. The alignment at the range you need is really not as difficult as it sounds; the beam is fairly divergent, both ways, transmitting and reflecting. Its the shielding to prevent direct reception you will have to be careful about. Take a look at http://www.rentron.com/PicBasic/infrared_object_detection.htm This is for PBP users, but you'll get the idea. Regards, Anand ____________________________________________________ On Yahoo!7 Photos: Unlimited free storage - keep all your photos in one place! http://au.photos.yahoo.com

> Hmmm. Looks like it's either an IR sig, modulated @ 38-40kHz, to a reflector > and back or a magnetic sensor, Honeywell probly. > The reflector set up would work, I'd say, but needs to be aligned + I'm > thinking about battery capacity if you're flashing the light non stop all day. > The battery wouldn't have to be particularly small, however. Okay, two things jumping in at the last minute. First, for an IR trip sensor, you need to modulate a signal at 38 kHz, and then THAT signal needs to be switched on and off, too. Most IR receivers will filter out a constant source of 38 kHz flashing light (or so I'm given to understand; may bear experimentation). Second, try NVE's line of giant magnetoresistive sensors. The most sensitive ones can detect a screwdriver a foot away; I think they'd have NO trouble with a car, even up to a couple of meters. They're also cheap. Mike H.

> > > Second, try NVE's line of giant magnetoresistive sensors. The most > sensitive > ones can detect a screwdriver a foot away; I think they'd have NO trouble > with > a car, even up to a couple of meters. They're also cheap. A large diameter coil, and current-voltage amp will detect cars quite a ways away. In hawaii, I expeimented with this using a six inch coil of a few turns, and was able to see traffic on the street three floors down and about 20 feet away.