Senior Project Help

Hello fred04

Initial thoughts:

Most home properties would be fenced, and that will make the job easier.

You could use RFID technology, but remember it only works within a few metres at present, so your sensor/s would need to be located further away from the house, towards the limits you set.

Other Idea:

It could be done by a regular pulsed signal sent from the child or machine and if the signal is too weak, the pulse does not arrive on a regular basis, and a radio signal could be sent back to the toy, to interrupt the power to the wheels etc, and/or sound an alarm at the toy/house/your cellphone etc.

The above two systems sprang to mind rather quickly.

Kind Regards....

There is much more input required in this aspect.

Like do you want the system to be area based or through specific location.

If you want it through specific locations like that of gates and exits thro which the machine will be forced to go through then a very simple solution in hand exists.Use a proximity sensor to cut off supply.

But since this is your major s project i suggest you do something more complex and impressive

Use an RF based system to create a monitoring system as to find out where the machine goes and cut the supply off when it reaches a purticular point.

Loads of ideas can be implemented in this regard and the above is just a small suggestion

There is technology similar to what you seek for pet containment. A system such as this could possibly be modified for your use:

http://www.invisiblefence.com/

I use this system for my dogs and it works great. You have to bury a wire along you property line.

Or, a google search:

pet_containment

Some of these use an adjustable radio beacon to set the range.

Hello,

Why RF?

Make Small preset pulse counter, put a magnet on wheel and hall sensor at some fix place to read the magnetic pulse at every rotation as a input signal.

send this input signal to your pulse counter which can shut off the cart motor whenever it exceed the preset limit.

Rakesh,

Your concept would be distance traveled not necessarily distance from the begining to its most distant point. If in the child example the child were to walk around a tree many times...

Yes good point, accepted.

I'd rather go with having an RF transmitter putting out either a constant sinewave signal. The toy would have a receiver which provides power to the motor as long as the receiver gets the transmitted signal. If the signal goes below a certain threshold, the power to the motor is cut off and the toy stops.

Of course, that doesn't prevent the child from picking up the toy and bringing it farther away.

If you want to detect the child instead, put the transmitter in the toy and the receiver in the house. If the receiver doesn't "hear" the transmitter, it calls the police . Or if you want to be ordinary about it, you can just have it sound a buzzer or something.

Hello fred04,

How about a wire attached to the back of the toy, while the other end is attached to a bell. Can even be attached to a safety switch to cut power. Covers all basis and is cheap. Just kidding.

Actually I like the RF idea, but using loss of signal as the trigger has problems. Field propagation, and interference to name two.

Instead, how about using a receiver/transmitter as both the base and mobile units using a digital signal. By using the base station to send out a coded signal and the mobile unit to return a signal, an accurate distance can be determined by comparing send and receive data timing. By using this method, certain benchmarks can be set to alert either or both units, such as change of location of said object or approach and breach of containment boundaries. These parameters can be changed easily at anytime through the base station user interface. Other features such as instant stop, call back, communications, or panic trouble alarm can be incorporated into the product.
Also several mobile units can be set to use one base station while allowing the above said benchmark properties to be individually set for each mobile device. This also allows several different units to be used in close proximity without interference.
Though the use of several (3+) base stations, triangulation data can be used to determine exact location and can be used to set particular boundaries, or no-go zones. This can also be connected to other systems such as computer mapping and camera monitoring systems. The possibilities are nearly endless.

Using loss of signal as a final failsafe is a good idea.

But since this is your homework assignment I will leave the details up to you.

Good Luck

Hi,

currently there are systems that are used to keep dogs within a perimeter, and these are comprised of collar receivers placed on the dogs which invoke a high voltage, low amp pulse when the dogs approach a perimeter defined by a wire loop buried a few inches below the ground around the area defined by the owner to keep the dogs in. The wire is energized with a low voltage signal that is detected by the receivers on the dog collars

hope this helps

quantum engineering

This works

http://video.search.yahoo.com/video/play?p=shocking+dog&b=22&ei=UTF-8&fr=yfp-t-309&fr2=tab-img&tnr=21&vid=000111008496

Reminds me of "Kinderkatch" which was the lab name of a device using signal strength (or loss of) for babysitting toddlers, some 20 years ago.

Today, I would use GPS. Enter start longitude and latitude (into the Powerwheels), and turn the Powerwheels off if it went outside the area prescribed (in seconds of longitude and latitude).

I discovered that the length of our house is approximately .6 seconds in latitude thus if we were to set our shutdown device to 1 second of arc, it would call a halt shortly outside the perimeter of the house.

We do not do homework but I hope to have opened you to some thoughts...

Bill

find a builder of shopping carts ithe rfid capacity, i think there is more than one out there.

'da ber

Cameras aimed along the edge of the perimeter of the area the child is allowed to play in. The cameras should be connected to a digital recorder that has motion detector technology that will record, or start another function, when the camera sees the child. That other function would be an override to the controls of the Power Wheel that would cause the toy to return towards a predetermined location. After the child is out of site of the cameras for a predetermined period of time the control of the toy would again return to the child. This would serve a second benefit. If an intruder was to enter the property, the child would be brought back to the safety of the house, or other predetermined location. The monitor should be equipped with a audible warning device and override button to force the toy to return all the way back to the safety location.

There is my idea. Now all you need to do is put all of this existing technology together. Good luck.

My radio theory has gone to pot since I last used it in earnest 40years ago but wouldn't the best way be to send two radio signals out on slightly differing frequencies modulated with the same frequency. The resultant of the addition of the signals will produce standing waves of coincidence every so often in a circular moiré pattern. A change in one frequency will change the distance of the first ring of coincidence.

If I've got my maths right (and I may well not have) then 27 MHz and 27.1 MHz should give a sync point at about 123m (405ft). Detect this and shut down the toy, or, other way round start the alarm.

This has one added benefit, if you stay close to the transmitter where the signals are also in sync then the little blighter can't run into you legs with his turbocharged wheeley toy!

I'm thinking shopping cart anti-theft. When the carts at some supercenters are taken past a pre-determined boundry the rear wheel is clamped down preventing the wheel to move freely.

don't recall seeing such a fancy item in these parts but it seems like you follow my idea and those of the ikotrol systems that came from germany in the late "80's

'da ber

Thanks for the help. I think im going to go with the RF, dog fence idea. This seems to be a good idea for my project. Now all i need help with is drawing the circuit diagram for this project and finding the right parts for it. As u can see, i am quite lost right now.

hi,,i'm an undergraduate student in communication engineering,i was searching for an idea for my project,,, and i'v just read all the conversation about ur project,,it's approixematly year ago,, i like the idea and i was wondering what happend with ur project and i would like to tell me in details...