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Author Topic: Electronics expert needed!  (Read 4009 times)

omra85

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Electronics expert needed!
« on: October 12, 2009, 11:06:49 AM »

Hi All
I need a bit of help with some conceptual thinking and I'm pretty sure that Mayhem has such thinkers  :-))  (bull, bull bull .....  {-) )
This is about an automatic lap counting system for use in OMRA races. I know the multi lads already use the BBK system but, to be honest, it seems incredibly expensive to me!
The BBK system works by having a receiver loop stretched out over the water with each boat having it's own transponder. When the boat passes under the loop, a unique signal is sent to the receiver and then to a laptop which adds and displays the number of laps (it also records times).
Now, I am not the world's best when it comes to electronics (I can just about work out a resistor value given long enough) but I was thinking -
1. Would we actually need a loop aerial or could we use a single point aerial, say on the bank next to the pits? If we did need a loop, it would have to be long enough (say 10-15 mtrs from the bank) and high enough for the boats to get under (say 800mm above the water). I accept that this probably could not be used in sea races as the height variation may be too great, but should be fine for lake races.
2. What sort of transmission device would be needed in the boat? (It should be small and light with a rechargable battery that would last at least an hour). Could the latest generation of 2.4GHz keyfob type transmitters be used? (they would have to be encapsulated for waterproofing).
3. The receiver would need to be operable on 12V.
4. A laptop could be made available with appropriate software to count/display the laps (commercial stuff is available and not TOO expensive).

Any thoughts guys, or do we have to go down the "commercial" route?
Thanks
Danny
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Rubdown

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Re: Electronics expert needed!
« Reply #1 on: October 12, 2009, 12:03:09 PM »

I think that with car racing an aerial goes accross the track on above it,so I pressume they same system would have to be in place to pick up the transponder signal

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malcolmfrary

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Re: Electronics expert needed!
« Reply #2 on: October 12, 2009, 05:22:42 PM »

Making radio signals, picking them up and processing them was never my forte, I was more into stopping radio signals going where they shouldn't, but - as a rough guide, budget about 1000 per cubic foot for the base unit, then start adding the time spent researching a viable and reliable method of generating the signal, then differentiating when it passes through the "beam", with a unique signal for each competitor.
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DickyD

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Re: Electronics expert needed!
« Reply #3 on: October 12, 2009, 06:54:05 PM »

Why do you personally need a lap counter to count your laps Danny, you have a hand with fingers don't you ? {:-{
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dodgy geezer

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Re: Electronics expert needed!
« Reply #4 on: October 12, 2009, 10:34:24 PM »

I wonder if you could bar code the boats and use a surplus supermarket bar code reader. Or a shoplifting tag detector...
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omra85

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Re: Electronics expert needed!
« Reply #5 on: October 12, 2009, 10:42:17 PM »

Why do you personally need a lap counter to count your laps Danny, you have a hand with fingers don't you ? {:-{

Thought you wouldn't be long  %) %)

The microchip idea and the barcode both have the same problem - range. There is an IR system for model cars but I don't think it would be modifyable for boats (and it would cost a few hundred pounds to find out!!).  I know Maplins list Tx and RX units but I'm at a loss to know what to do with them!

Thanks for the replies so far though.
Danny
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HS93 (RIP)

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Re: Electronics expert needed!
« Reply #6 on: October 12, 2009, 11:05:22 PM »

in car racing the early systems where low power and we used a small bridge over the top of the track as the loop was bulky but I don't think it would be much fun having to get Ormra boats through a 6ft gate as the power in the modules got better and the loop got thinner it could go under the carpet this is the system that has been about from the start have a look on there site they now have lots of applications hat may do.


http://www.mylaps.com/mylaps/


peter
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omra85

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Re: Electronics expert needed!
« Reply #7 on: October 13, 2009, 08:03:59 PM »

Peter
Having checked your link I find that Mylaps is the new name for AMB. I rang Rob Nelson of BBK, who sell the AMB/Mylaps system and the prices are worse than I thought!
Just the receiver/decoder and the wire loop aerial is 2800, software 460 for non-expiry licence, then nearly 100 EACH PER BOAT for everyone to buy their own personal transponder.
Over 160 different boats have taken part in this years OMRA Championships which would have meant an outlay of 16000 by members to get their laps counted !
Given that the design is over 5 yrs old and the downward trend in all component costs, even if they are only making a few a year, that price seems awfully high.
I know Sweden are using this system as are the MPBA Multi section so it must work - but the initial costs...!
I think we may be pressing buttons for a few more years unless someone comes up with a cheaper way!
Danny
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HS93 (RIP)

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Re: Electronics expert needed!
« Reply #8 on: October 13, 2009, 10:57:41 PM »

at one time they just had 12 transponders for 12 car races as you came of you gave them to the people in the next race, but I believe they have there own now BUT I have seen them for sale very cheap, just a few pounds. try contackting the brca and tell them your predicament , it cannot be that expensive as most small clubs have a system now.have a read   http://www.carsrcracing.co.uk/?page_id=19   try contackting the chairman he is helpfull, he may tell you how small clubs can afford it.or the  http://www.brca.org/  also Spectrum do personal  lap counting equip, maybe that could be modified

Peter
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wombat

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Re: Electronics expert needed!
« Reply #9 on: October 19, 2009, 06:33:20 PM »

OK hows about this for a suggestion.....

Small unit within the boat with IR or other detector - maybe four or five in an arc to maximise reception coverage.  Have vertical bars on the start/finish gate that generate IR signals - modulate the IR to make it more detectable - or use lasers or xenon beacons.

Unit in the boat has a counter - this is reset ot zero at the start of the race - counts up by one each time the gate is passed. At the end of the race the timers from the boats are handed in and the lap count downloaded into a laptop. The number of laps and possibly individual lap times are downloaded and indicated.

Start and stop of the race is determined by switching on the IR beam from the timekeepers desk - no beam means no count.

My initial guess is that the unit cost of the counter system in the boat would be of the order of 50-100 worst case, maybe a couple of hundred pounds for the sender unit. An upgrade would be to add packet radio to the boat modules to report lap counts realtime - this would probably add about 20 per boat. It would also allow other facilities - such as remote shutdown of a rogue boat or throttle override in the event of a safety situation or for enforcing penalities

Wom

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omra85

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Re: Electronics expert needed!
« Reply #10 on: October 19, 2009, 08:15:11 PM »

Thanks Wombat, interesting idea.
I understand the principle but not the technicalities so I shall take these suggestions to our AGM and see if we have anyone who's into this kind of thing.
Cheers
Danny
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Harrison

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Re: Electronics expert needed!
« Reply #11 on: November 21, 2009, 09:14:24 AM »

Hi,

Is the expert still required?
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omra85

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Re: Electronics expert needed!
« Reply #12 on: November 21, 2009, 09:39:58 AM »

Hi Harrison
We have the AGM tomorrow with a vote for using number plates (not quite the huge advance into the future we would like but it's a start), but if you can come up with something, I'd be most interested.
Thanks
Danny
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Harrison

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Re: Electronics expert needed!
« Reply #13 on: November 21, 2009, 02:03:54 PM »

Can anyone briefly fill me in on the width of the finish line?
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andyn

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Re: Electronics expert needed!
« Reply #14 on: November 21, 2009, 07:18:56 PM »

We don't use BBK Danny, it's AMB now ;)

It's hurrendously expensive, something like 60 each :o :o :o :o :o :o

Can anyone briefly fill me in on the width of the finish line?

The wires are about 50cm apart.

Everythings logged onto computer then uploaded to the net, where everyone who took part can see race analysis (lap times etc).
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omra85

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Re: Electronics expert needed!
« Reply #15 on: November 21, 2009, 08:19:24 PM »

Can anyone briefly fill me in on the width of the finish line?

Unfortunately, the banks are of variable slope so it could be anything between 10 and 25 metres.
Would it have to be a loop type system?  It would be good if it could be just a singe point receiver aerial on the bank with a low range Tx on the boat.
Our problem (apart from cost) is that the "water" end of the loop would often be in very choppy water of variable depth.
Cheers
Danny

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andyn

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Re: Electronics expert needed!
« Reply #16 on: November 21, 2009, 10:14:00 PM »

Our problem (apart from cost) is that the "water" end of the loop would often be in very choppy water of variable depth.

You lot are tight ;) No problem there, the other end of the loop is on a big block of polystryrene with an anchor of some sort keeping it still.

(Preferably without boat attached, they don't help matters...)

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Harrison

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Re: Electronics expert needed!
« Reply #17 on: November 22, 2009, 05:08:51 PM »

Do all the boats have the same size numbers on them? I was thinking OCR at the finish line but I expect spray from other boats would prevent the numbers from being seen clearly on each pass, a shame as it would have beena very cheap and easy to setup system.
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malcolmfrary

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Re: Electronics expert needed!
« Reply #18 on: November 23, 2009, 09:57:27 AM »

Do all the boats have the same size numbers on them? I was thinking OCR at the finish line but I expect spray from other boats would prevent the numbers from being seen clearly on each pass, a shame as it would have beena very cheap and easy to setup system.
Barcodes?  Might be readable more robustly than numbers.  Dont know about the range, though.  Multiple simultaneous line crossings might be a problem as well.
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omra85

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Re: Electronics expert needed!
« Reply #19 on: November 23, 2009, 10:38:50 AM »

Hi Chaps
Thanks for all the input on this.
Unfortunately, even a proposal to have clearly visible number plates was voted out, so I can't see much chance of progress with this  <:(
Ah well, as an intellectual exercise it got my grey cell(s) moving - but even I know when I'm on 'a hiding to nothing'!
Thanks again
Danny
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dodgy geezer

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Re: Electronics expert needed!
« Reply #20 on: November 23, 2009, 11:04:29 AM »

Hi Chaps
Thanks for all the input on this.
Unfortunately, even a proposal to have clearly visible number plates was voted out, so I can't see much chance of progress with this  <:(
Ah well, as an intellectual exercise it got my grey cell(s) moving - but even I know when I'm on 'a hiding to nothing'!
Thanks again
Danny



Ah, well...

Incidentally, I wonder if we were thinking about the requirement to 'detect the boat crossing the line' from the wrong angle.

Instead of trying to detect a boat passing a defined point, we could just detect the boat's position at all times, which would enable us to know when it had passed any particular point - in fact we could see its track during the whole race. The sort of thing I'm thinking about is miniature GPS transponders. I note that the 'High Altitude Glider' project used GPS boards costing about 25 which talked back to base, and there are occasionally stories about pet tracking units in the press. I don't know of any currently available products, but I am sure they will come as the Galileo satellites come on line.

There could be all sorts of spin-offs from using this technology - drivers would get data on their driving, and race officials could investigate any claimed issues....
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