heart rate sensor

felix
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heart rate sensor

Postby felix » Sun Dec 30, 2007 11:17 am

Anyone ever tried to integerate a heart rate sensor, the kind that clips to your ear or the around the chest strap style?

jlucas
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Postby jlucas » Mon Dec 31, 2007 4:09 am

I always thought this would be an interesting one to try.

Let me know if you find something that works.
Jeremy Lucas
Fast Tech Limited - a Race Technology Dealer

scorpia
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Postby scorpia » Sun Nov 08, 2009 8:17 am

i thought it would be interesting as well - did some research, rowing sport uses this sort of stuff - the chest straps spit out a magnetic pulse on each beat, the heart rate monitor type watch we wear when exercising picks up these pulses and counts then displays on the watch face. The box you can buy receives the pulses and converts them to a pulse output - reasonably easy to integrate to dl1 i think.

ive seen kits for receiving and converting when rowing either on a machine or a boat - didnt appear especially expensive - will get back to you with some web links etc...

scorpia
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Postby scorpia » Tue Mar 16, 2010 11:03 am

fyi. i dont work for them, havent dealt with them, only researched the issue and thought that the product may well work with a DL1.

couple of things:

1. i would make up an adaptor plug so you dont have to chop the cable on the receiver - this way you can sell it when u are finished, or use it @ the gym on the rowing machine.

2. i note the australian distributor lists the prices as twice as much as the US one - our dollar isnt that bad! Shop around.

Have fun!

http://www.concept2.com/us/indoorrowers/accessories/hrequip.asp

Maxx
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Postby Maxx » Thu Mar 18, 2010 1:28 pm

We are working on just such a device and hope to test next week. We are also using the video and intend to show heart-rate on the video.

Will update this thread with our progress.

Malcolm

scorpia
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Postby scorpia » Fri Jul 16, 2010 3:48 pm

Maxx wrote:We are working on just such a device and hope to test next week. We are also using the video and intend to show heart-rate on the video.

Will update this thread with our progress.

Malcolm


update?

Maxx
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Postby Maxx » Fri Jul 16, 2010 4:15 pm

Sorry, I had forgotten I had posted this.

We have done more with it and you can see the results in this video : http://www.youtube.com/watch?v=f_YCkAwIf7c

Progress is slow as it's just a friend of mind doing it in his spare time plus we didnt follow up for a while.

We use a Polar Chest-Strap (bought watch & strap for £40) and a custom receiver module. At first we mounted the receiver on the top of the windscreen and got a decent signal but seemed to be intermittent (they give max range as 0.8mtr unobstructed).

We then tucked the receiver unit in the drivers racesuit, this seemed better.

I dont know much about the way it works apart from the DL1 gets fed with a frequency and this relates exactly to the heart rate.

We do still seem to get some anomolies which I still think is down to loss of signal. I suspect it's at the transmit end, the driver doesn't sweat much and the chest band needs moisture to work, we tried to get some conductive gel but couldn't before our last test.

I'm not sure what happens with the data the unit sends to the DL1 if there is no data coming from the chest strap, so I need to get my guy talking to RT but he's particularly busy at the moment.

What we see are odd rises and falls on some laps which have no relation to others. I got round it a little by setting a realistic maximum rate of change but am sure there is still an issue with the underlying data.

Incidentally, many have expressed surprise at the heart rates shown, I was initially even though I have seen similar on V8 Supercar footage who occasionally show heart rate.

I do know that a drivers' biggest problem is lack of (or rather very shallow) breathing, and this sends the heart rate sky high as it needs to pump harder to get teh required oxygen to the brain.

The driver in the above video was tipped into a triple spin at over 100mph (at around 3:00) and we could see after his heart rate rocket. The raw data actually went to 236 but the max rate of change we used meant we never saw that.

I was very sceptical but apparently it's not uncommon to see this type of rise in these sorts of circumstances.

We will be running it again on Sunday but have done no further work as yet. I'll try and post any news on this thread.

Maxx

scorpia
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Postby scorpia » Sun Jul 18, 2010 4:54 am

yah ive seen odd readings when used with different brands of exercise machines - also ive seen HR displayed on a treadmill when i wasnt wearing the polar sender - someone 2 metres away was!

conductive gel sounds like fun, ive been known the soak my chest strap in water before exercise and it works great then. saliva or salt/chlorinated water has the same effect.

what does the box output? pulse or voltage? Ive just changed tacho output type on my ECU and now am using 5volt - this will free the frequency counter channel up for me to plug in the HR monitor.

Im considering displaying the HR on the dash - will be a good reminder to breathe - no doubt we shallow breathe as we are in a snug seat - good for support during cornering but bad for physiological/cognitive function. Sounds like a fantastic topic of discussion with some red wine if you ask me :)


With your custom rx module - did you make it @ home or is it something like the link i put up in an earlier post?

im going to order one of these modules in the next few days.

given that the tx method is magnetic pulse, it would be clearly susceptible to ignition discharges / solenoid operations etc that are found in a car, not much we can do about this except explore the options of wired ie non magnetic transmission protocols and shielded cable.

scorpia
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Postby scorpia » Sun Jul 18, 2010 5:27 am

just looking @ your engine restart after your spin you have a huge EMF discharge that pissed your cameras - definitely some need for RF choking devices around there - are you using shielded cable for your data stuff? belden 8723 with a shielded ground wire is always handy:)

didnt know you drove a mex - me too. my datalogger shows a 10km/h improvement in top end speed in my NA6 at phillip island with the roof up vs roof down - sure visibility is a bit compromised and the cage has to be made to fit but its worth it :)

Maxx
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Postby Maxx » Tue Jul 20, 2010 8:02 am

Scorpia,

scorpia wrote:yah ive seen odd readings when used with different brands of exercise machines - also ive seen HR displayed on a treadmill when i wasnt wearing the polar sender - someone 2 metres away was!


Yes, We use the watch to check we are getting tramsmission and we have found it works easily up to 2mtrs, I know that there is an option to get a 'coded' system, which links the strap and the watch so you dont get interference from others close by.

conductive gel sounds like fun, ive been known the soak my chest strap in water before exercise and it works great then. saliva or salt/chlorinated water has the same effect.


We start with it wetted and I think it probably does work even though my guy doesn't perspire much, it's just that, at the moment, I'm not sure what you would 'get' if there was an interuption. We dont get any 'zeros' but we do get a climbing trace or a descending trace that doesn't look real. When I get a moment I will post a screengrab of the traces.

We didnt get any data on Sunday, got caught out on time in race 1 so couldnt get the strap fitted and we didnt get any data from race 2, probably finger error :(

what does the box output? pulse or voltage? Ive just changed tacho output type on my ECU and now am using 5volt - this will free the frequency counter channel up for me to plug in the HR monitor.


I dont really have a clue, a buddy of mine has done all the electronics. We get the data on FREQ3. We dont have 'Pulse Counting' or 'Period Measurement' set in the DL1 config just "Freq Measurement". We have the units set at 'cycles per minute' which gives us our heart rate.


Im considering displaying the HR on the dash - will be a good reminder to breathe - no doubt we shallow breathe as we are in a snug seat - good for support during cornering but bad for physiological/cognitive function. Sounds like a fantastic topic of discussion with some red wine if you ask me :)


I'd like to, and have spoken to my guy about actually going further and also getting a blood/oxygen reading. Aparently we can get heart rate and blood oxygen via a 'ear clip' (probably other ways but this sounds like the best).

With your custom rx module - did you make it @ home or is it something like the link i put up in an earlier post?

im going to order one of these modules in the next few days.


As I say, it's a buddy of mine, he won't have read the forum I suspect so gone his own way, all I know is that he uses the standard Polar Rx module with some other custom electronics.

given that the tx method is magnetic pulse, it would be clearly susceptible to ignition discharges / solenoid operations etc that are found in a car, not much we can do about this except explore the options of wired ie non magnetic transmission protocols and shielded cable.


As I say, we know clip the Rx module to the racesuit just in front of where the chest strap is. We do use shielded cable, not sure on spec though.

Maxx

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Postby Maxx » Tue Jul 20, 2010 8:04 am

scorpia wrote:

didnt know you drove a mex - me too. my datalogger shows a 10km/h improvement in top end speed in my NA6 at phillip island with the roof up vs roof down - sure visibility is a bit compromised and the cage has to be made to fit but its worth it :)


The regs don't allow us to run with a hardtop so no option there but is the same for everyone.

Maxx

scorpia
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Postby scorpia » Mon Oct 11, 2010 5:07 pm

okay ive ordered one of these receivers, it should be here in a day or 2 - im going to put it on a cro and see what sort of wave comes out of it. Im expecting a simple pulse from it.

any suggestions on the equation to show heart rate in beats / minute?


Maxx
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Postby Maxx » Mon Oct 11, 2010 5:35 pm

Scorpia,

End of the season for us in the UK now so on the back burner a bit. One of the issues we had is what happens when, for whatever reason we dont receive a pulse/signal and we are having to include circuitry to deal with that.

Don't ask me what though, it's a friend who is developing it.

Maxx

scorpia
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Postby scorpia » Mon Oct 11, 2010 5:38 pm

cheers Max.

my questions more about the equation - i will give the hardware a shot myself.


Im hoping that those that are more experienced than I will be able to shed some light on turning Hz into BPM. Im thinking it is Hz*60

felix
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Postby felix » Thu Oct 21, 2010 2:38 pm

scorpia wrote:okay ive ordered one of these receivers, it should be here in a day or 2 - im going to put it on a cro and see what sort of wave comes out of it. Im expecting a simple pulse from it.

any suggestions on the equation to show heart rate in beats / minute?



Can you point me to a source for the receiver?


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