Bluetooth Proximity Sensor

Guys I'm a noobie and I really need help. I have been tasked with a small project that I really am trying to get my head around.

We have small kids battery ride-ons in a shopping center and the kids can ride these things everywhere. The issue is I want to stop the ride-on when ever it gets to an exit, escalator, carpark entrance... etc you get the point.

The range I want the ride-on to stop is around 5-10 meters from some sort of a proximty beacon which is where I think bluetooth would be perfect.

I have multiple ride-ons and multiple exits to cover

The arduino on the ride-on only needs 1 output to turn on a relay to kill power on the forward motor (they can still reverse)

The arduino at the exits are basically continuously sending out a signal like a proximity beacon

Is this possible to do the above? Which Arduino's/add on modules would suit to do this? Would a nano and RN42 do the job for both ride-on and beacon? Any other way of doing the above easier?

Any help would be greatly appreciated as this is a whole new world for me!

Bluetooth is not a good option. By the time pairing/connecting is done each time something comes into range, your desired distance barrier is moot.

If your transmitting modules at each point will be plugged in so battery life isn't a concern, I would set up multiple IR diodes to transmit a signal. Cars with a few receivers will detect at about the same range as you have in mind, and it's a much simpler and cheaper system.

I'm not sure if you are trying to describe a central "beacon" which stops a car when it gets beyond the effective radius or a "danger beacon" at each exit which stops a car when it come into range.

In either case I doubt if Bluetooth would be suitable as it relies on two units being paired. And I don't think the signal strength would be a suitable distance indicator - I don't think it would be sufficiently precise where safety is concerned.

The only thing I can think of is some sort of beam-break system - but even then I can't immediately think how the car that should stop would know that it is the one that has broken the beam.

One idea might be an IR transmitter that continuously sends a message (doesn't really matter what). The light from the transmitter would be screened so it would only be detected by a sensor on the car if the car was where it should not be. If the car could receive the message it would know to stop. But if something else (such as shopper) accidentally blocked the beam the car would not stop.

However, for a safety system I would much prefer a system in which the car would only work if it could receive the signal. Then the system would fail safe. But organizing that might be more complicated. You are unlikely to want unsightly shrouds at danger points just to block an IR signal.

Just my 3 cents.


Wow you guys are quick!!

All good points guys. Was trying to keep this simple but currently the owner of these things have a couple working that were setup already. from what I can make out. The cars turn off when they come into proximity of a beacon

RIDE-ON has a DUE board and some shield which I can't find anywhere, the Shield has a RN42-I/RM and a Microchip RN2483 on it, various electronics, 3 leds and a 2 pole dipswitch

BEACON seems to have a copy/ripoff of a NANO board and another shield board which I can't find anywhere, The shield also has a RN42-I/RM, an led and a 4 pole dipswitch

The complication for me is trying to replicate what they have already as they don't know who originally built the devices or how they work exactly. As far as my little understanding of Arduino is that I can't read the code in them only write to them. So therefore I'm trying to start from scratch to make all the devices the same and future proof it when they add more rides-ons

I though of IR curtains but the dilemma is not many power points around, the centre is hesitant in letting us plug in as well and battery technology is prefered

I will take pictures of the boards and post links soon

I haven't seen the cars or them working but have been told that they do. I got roped into this because I'm a bit cluey with tech and the others wouldn't know what a resistor is if you get my point!

Here is a dropbox link of the pics of the boards

We have small kids battery ride-ons in a shopping center and the kids can ride these things everywhere. The issue is I want to stop the ride-on when ever it gets to an exit, escalator, carpark entrance… etc you get the point.

My local Marks and Spenser store has physical barriers to prevent pushchairs and wheelchairs acessing

Local supermarket has jam wheels on the trolleys to prevent theft.

I think that this works with a bueried perimiter cable though.nt

You could do it with a pair of ultrasound rx/tx devices - the fixed one would be a simple transponder..



This is not part of the shopping centre facilities, these guys hire a stall and then "rent" the little cars to parents for their kids to drive around the centre. In 6 months time they may packup and rent a stall in another centre So all this must be easy to install and remove without defacing anything in the centre

The board on the cars (DUE) has other wires on it and I'm told that these are for the ultrasonic sensors front/rear the cars. If they come close to a eg: a wall, the car stops and can only reverse. If they are reversing and there is someone behind them it will only go foward (as long as there is nothing infront of them!

They also handed me a Bluecats Model BC303 which I have no idea if they are using that straight out of the box or if it's been modified or somehow code put into it.... don't even know if it works on their current system but none the less they threw it into the mix! Maybe a clue

Allanhurst.... I'm listening, is that multi directional and proximity adjustable?

Yes - the beam of an ultrasound tx/rx is pretty broad.

You send out a (coded?) pulse from the car which the fixed detector will detect and respond with another ( different code) pulse. By now the car has swapped to receive, and times between the end of it's send and the start of it's received pulse. Knowing that sound goes at 1100ft/sec, you can easily figure out distance.

You could make the pulses coded to as to prevent false detections - eg a car picking up another car.

And make the fixed transponders send different codes depending on how close you want the cars to get......



Sounds complicated in the sense of how do you send/recieve out coded messages via the ultrasonics, is that a standard module you can add onto a nano?

There are many cheap ultrasonic devices available - eg

as for coding - on/off short and long pulses, just like morse or uart protocols...

there are several libraries available which make all this easier...



Don't those send and receive via the same board?

Can you point me in the right direction because I simply can't find anything regarding coding between 2 Ultrasonic units. Everywhere I look its all about distance measuring

read my posts again. Each station has to have both a transmitter and receiver....

and you'll have a lot of coding to do/