Any ideas on how to accomplish this?

[bartman]

I'm just rolling this around in the back of my head for a project.

I live in a rural area and we have problems with hunters driving through the yard without stopping to ask permission to hunt or to even be on our land in the first place. We don't always see them go through, but find evidence of what happened later.

We also have a problem with wild animals walking through the yard.

Now, a simple motion detector in the driveway can alert us if either a deer or a vehicle goes past, but it can't distinguish one from the other. It might go off in the middle of the night and we see it's just a deer going past the driveway. We'd like it to go off if a vehicle goes through (night or day), but not when a deer goes past. In other words, wake us up if someone drives in the yard, but ignore the deer or other animals walking through.

I'd like to build something that sees the vehicle, ignores the deer, send a radio signal from the driveway to the house to sound an alarm and runs on a 9v battery for extended periods of time like the existing motion detector does.

All of this should be easy except the detection process. Any ideas on how the PIC could tell the difference and possible related hardware? Remember, for now I'm just toying wiht this idea.

Thanks.

Bart

[Ingvar]

Since most vehicles are made from steel and most wildlife ain't, i'd try to detect the small magnetic shifts the iron/steel will produce. You might fail to detect nascars, and get false readings on any deer with piercings ;-), but hey, what do you expect for a few dollars. Philips make a range of small magnetoresistive sensors(KMZxx). I'd use one with built in set/reset coils, KMZ51 springs to mind(or the dual KMZ52). There are some appnotes on Philips website.

/Ingvar

[sayzer]

Here is the solution for you Bart.

I would not draw this if the deer were not the subject!

Attached is the concept.
Two laser pointers crossing the yard placed with a distance to each other that is small enough to be intercepted at the same time on a vehicle pass AND also big enough not to be intercepted at the same time on a deer pass.

- You may want to add a third laser for height detect.
- You may want to consider the legs of the deer for safer detect.

- A car can be best detected with front, rear and top lasers; all being intercepted at the same time for activating something.

You can come up with the code I believe.



---------------------------

[Acetronics2]

Hi, bart

Some natural scenes like a little river, some rocks here and there .... and so on could definitly stop bicycles, bikes, Quads and motorized vehicles.

And that would be valuable for your environment ...

that what we've done to stop trespassing through our model planes landing ground ...

Alain

[dhouston]

Cartel driveway sensors react only to moving metal.

[sayzer]

Cartel driveway sensors react only to moving metal.

They are nice and quite effective but cost over US$150 and the range is 50ft to 70ft.

Look at my "design under five minutes" !
It costs below $10 and the range is over a mile!


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[Luciano]

Sayzer,

What is the correct distance between the two laser beams?

(Click to enlarge)
http://img10.picsplace.to/11/thumbs/deer_x3.JPG (http://img11.picsplace.to/img10/11/deer_x3.JPG)
(Click to enlarge)
http://img10.picsplace.to/11/thumbs/deer.JPG (http://img11.picsplace.to/img10/11/deer.JPG)

Best regards,

Luciano

[bartman]

All good ideas. I like the lasers and appreciate that you drew it just for me. I'd need to work on that one to account for more than one deer coming in at a time (we've had up to 20 standing in the yard in a pack so they would cover both beams quite easily. Maybe some speed or timing routines).

The magnetic field detector also sounds cool if it has some range.

I probably could just buy the one for $150.00, but that would take all the fun and stress of building it myself away! I need to finish my current project, but I think this is a good one for next. If I can do it cheap enough I could cover a couple areas of the farm that could use some coverage.

I'd be introducing myself to all sorts of PIC commands and routines to delight and confuse me!

Thanks.

Bart

[Melanie]

There's also Pressure Sensitive Cable... but Luciano's Gay Deer might exert the same point-weight as a vehicle. Then there's a variation such as Piezo Cable... that would give you a different signal profile from a point-weight such as a hoof than from a tyre.

However for a real cheap option, this is my favourite...

[Ron Marcus]

I did some work for a client interested in perimeter detection/identification. He had a magnetic vibration sensor, which was simply a magnet suspended on a spring, inside a coil of wire. It was amazingly sensitive, and could pick up a person walking 50 feet away. There is all kinds of algorythm software to identify vibrational footprints and distinguish between vehicles, wildlife, Al Queda, etc.

Ron

PS...Those deer are probably from Vermont! Civil Union...It's not just a law, it's a Man-date!

[Archilochus]

To keep it low power for the 9V batt, you could have an ultra-low power PIR sensor that 'wakes up' the other detector (LASER, magnet, vibration, etc) only after motion is detected. I use a similar setup on some of my automatic wildlife trail-cameras.

Then - after it's confirmed to be an auto - raise up the tire spikes }:-]

Arch

[Luciano]

More cheap options out there....

(Click to enlarge)
http://img10.picsplace.to/11/thumbs/trespass.jpg (http://img11.picsplace.to/img10/11/trespass.jpg)

[bartman]

I hadn't considered the tire spikes yet or the automatic weapons popping up from hidden bunkers. I might need more than that 9v battery powering this.

I best have my software bang on (no pun intended) or I might find myself full of holes when I forget to turn it off!

Bart

[sayzer]

Sayzer,
What is the correct distance between the two laser beams?
I did not know about deer group work!

Since Bart said that they appear standing all together, placing the laser beams at a height low enough somewhere around the tires of vehicle and also around the legs of the deer could be ok. Bart can find the correct height with respect to the ground. And if there is a group work going on, Bart’s code may also detect it! :-)

Also, considering an average vehicle speed and putting a second set of lasers somewhere after the first set (say 20 meters), can provide much much safer detect. Costs $10 extra!

- May use small pieces of mirrors and can control the entire circuit from home. No battery is needed! Remember, the range of cheap (US$2.0) laser pointers is over one mile and if you get a good quality one you get about 10miles.

Also, here is my version of social warning (modified from Melanie's)

<a href="http://img10.picsplace.to/11/warning2.JPG"><img src="http://img10.picsplace.to/11/thumbs/warning2.JPG" alt="Image Hosting by PicsPlace.to" ></a>

[Archilochus]

Don't know if this is what Melanie was referring to with the pressure sensitive cable... but I just remembered something from back when I used to live in an area with 'full-service' gas stations... They had a hose run across the pump area, and when a car ran over the hose the change in air pressure [I think] in the hose triggered a sensor with a bell in the service bay.

Seems like even if a deer did step on the hose, it might not displace enough air to cause a trigger.

Of course it would only work on a hard, fairly smooth surface.
Also would be hard to hide from the trespassers, who will be likely to destroy any sensors they find.

Arch

[Acetronics2]

Seems our friend Sayzer has re-invented the wheel ....

http://www3.telus.net/chemelec/Projects/Alarm/Laser-Alarm.htm

.... no comment, I bought some 2N5777 about 35 Years ago... and they are always here !!!

Alain

[sayzer]

Any progress out there?

[ronsimpson]

You want to cense cars and not animals.
1.)Place a rubber hose across the road. Plug the far end. Close end has a pressure censor. The hose should not be airtight, it needs a small hole [leak]. When a car drives over the hose, the air pressure changes.
2.) I have a commercial device. There is a “coil” in a PVC tube buried under the road. The coil oscillates. The frequency is not stable, it slowly drifts over time. When a car passes over the coil the frequency changes fast. It is built on a ‘metal detector’ idea.
3.) I now am playing with flux-gates for another projects. It appears I can detect large metal objects 20 feet away. Too complex but fun.

I can supply details if you need it.

[Archangel]

Love those bureaucratic words, Traffis lights around town use a large coil of wire under the street to sense the metal vehicles presence. I believe a smaller coil is there too as the tank coil of an oscillator. I remember seeing metal detector circuits over the years that used 2 coils, and you would null out the circuit, when metal appeared it would throw the circuit out of Null and it would oscillate. I believe the coils were supposed to be at right angles to each other.

Another suggestion: Radio Shack sells a cheap / toy metal detector, it might be the basis of what you need.

Last Idea, bury a sheet metal plate,or install overhead or on side, and hook to a darlington transistor switch circuit. the vehicle might induce enough stray capacitance to trigger switch.
Cheap enough to experiment, anyway.

edit : Doe! sorry Ron, I didn't see your mention of metal detector.

Melanie: I like it!
JS
http://www.ssec.honeywell.com/magnetic/datasheets/an218.pdf
http://home.clara.net/saxons/bfo.htm
http://www3.telus.net/chemelec/Projects/Metal/Metal.htm
http://home.skif.net/~yukol/MetalE.htm
http://electronics.howstuffworks.com/metal-detector3.htm
http://www.absoluteautomation.com/driveway_alarms/index.html