Need ALOT of help on an interesting project.

[somekyleguy]

I am a complex manager of a small apartment complex with 50 parking spaces in two 25-space rows in front of our building. I want to create 50 small devices to implant under the concrete that will detect a vehicle magnetically and show a red or green light in a control panel near the main office.

I was wondering if anyone could draw up a schematic and list of materials for just one of the devices. I was going to try and put them into a waterproof film canister and use a long branching cable to each one that will send power and receive data (whether or not the car was present) from and to the control box.

I don't know if this is too hard or not. Any help would be appreciated.

Thanks.

 

[(*steve*)]

The only way I've seen this done was by embedding a large coil under the road surface (we're talking several feet across). I've no doubt there are other methods.

The problem with embedding them in concrete is that if anything fails, you're stuck with it.

You might consider one of several other options:

1) ultrasonic sensor above the bay reading the distance to the ground. The ground will "rise" when a car is parked there.

2) a LED and a photodiode in the ceiling pointing at a reflector on the ground. (this can be a very rugged device like those placed on roads). When a car is there, the reflection is no longer detected.

3) a fixed surveillance camera with some image processing to determine if a bay has something in it.

 

[somekyleguy]

Those do sound pretty familiar but there is no overhead carport and I believe the angle that the camera is placed at would make it impossible to count the spots.

 

[duke37]

Traffic lights in the UK often have vehicle detectors to optimise the light timings. These are coils which are embeded in the road surface by cutting a slot with a diamond saw. The coils therefore are rectangular.

I do not know how the detection circuit works or how you would protect against the biscuit tin lid trick.

Fifty cables would be a very large and expensive job, It may be possible to pole the devices and use one cable.

 

[KrisBlueNZ]

Perhaps a number of cameras with image processing software, or a large pressure pad at the back end of each parking space. The first option is sure to be cheaper and lower-maintenance.