Data Aquisition Question
#47
Drifting
Join Date: Sep 2002
Location: La Jolla, CA
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Originally Posted by SundayDriver
Kary,
How does a GPS system do over/understeer? I have seen claims that using 2 sensors (front and rear) will do it, but the physics make that very doubtful.
How does a GPS system do over/understeer? I have seen claims that using 2 sensors (front and rear) will do it, but the physics make that very doubtful.
Not sure how to really do it in the manner you have described. I am trying to figure out some of the channels needed on my G2X. The G2X has plenty of calculation capability. Last night I did a Total G's calc (SQRT( POW(Lat G,2) + POW(Accel G,2)). It showed some interesting things with my data as compared to a professional driver on the same track.
I will post some of my calcs when I get them built and perhaps all of us here can do a work in progress with each of our repsective DA systems.
#48
Race Car
WOW, I wish I would've read this thread before I purchased my DAS setup!
Did I screw up when I ordered a Traqmate complete system? I haven't heard anyone mention on on here but does anyone reading this thread have one, or experience with one? It is a GPS based unit, seems pretty useful and the price was right for someone (myself) that isn't too sure he needs DAS setup just yet.
I understand that Trackvision software is compatible with the system and there are some basic inputs I can incorporate like the tachometer and others, not sure how the brakes/steering/throttle inputs play in...if at all, didn't do too much research prior to purchase.
If anyone has any input on my new acquisition (no pun intended) or any further insights - I'd like to hear it.
Did I screw up when I ordered a Traqmate complete system? I haven't heard anyone mention on on here but does anyone reading this thread have one, or experience with one? It is a GPS based unit, seems pretty useful and the price was right for someone (myself) that isn't too sure he needs DAS setup just yet.
I understand that Trackvision software is compatible with the system and there are some basic inputs I can incorporate like the tachometer and others, not sure how the brakes/steering/throttle inputs play in...if at all, didn't do too much research prior to purchase.
If anyone has any input on my new acquisition (no pun intended) or any further insights - I'd like to hear it.
#49
Lifetime Rennlist Member
Originally Posted by Jeff Curtis
WOW, I wish I would've read this thread before I purchased my DAS setup!
Did I screw up when I ordered a Traqmate complete system? I haven't heard anyone mention on on here but does anyone reading this thread have one, or experience with one? It is a GPS based unit, seems pretty useful and the price was right for someone (myself) that isn't too sure he needs DAS setup just yet.
I understand that Trackvision software is compatible with the system and there are some basic inputs I can incorporate like the tachometer and others, not sure how the brakes/steering/throttle inputs play in...if at all, didn't do too much research prior to purchase.
If anyone has any input on my new acquisition (no pun intended) or any further insights - I'd like to hear it.
Did I screw up when I ordered a Traqmate complete system? I haven't heard anyone mention on on here but does anyone reading this thread have one, or experience with one? It is a GPS based unit, seems pretty useful and the price was right for someone (myself) that isn't too sure he needs DAS setup just yet.
I understand that Trackvision software is compatible with the system and there are some basic inputs I can incorporate like the tachometer and others, not sure how the brakes/steering/throttle inputs play in...if at all, didn't do too much research prior to purchase.
If anyone has any input on my new acquisition (no pun intended) or any further insights - I'd like to hear it.
The big difference when you step up to MoTec or Pi (Pro stuff) is the power of the math, ease of use, channel count, and resolution. Case in point - guys are builing math channels in another thread to do inverse corner radius, combined g's etc. This is stuff that is already in the pre-configured math from the higher end systems (even Stack offers these built in). MoTeC not only does that, but can do some amazing math IN THE DASH IN REAL TIME. You can display all of this stuff if it is important to you. You have logic that can eliminate data points that are not valid, based on speed or any other status. The list just goes on and on.
Here is another example...
Brake aggressiveness. Calculate filtered brake pressure (maybe over 20+ readings at 50Hz), then subtract that from brake pressure to see how aggressive the driver is being on the brakes. Do that with steering as well. If you know your car, you can even set an alarm that tells the driver they are pushing too hard and will destroy the tires, so they need to back off.
Here is a simple one - calculate brake bias. Not just F/R pressure, but calculate pad clamping force by using piston sizes so you have a real brake bias of relative force. Now have that display on the dash, but make it take the place of something else only when front pressure exceeds 50 psi. This is pretty easy to do with MoTeC. Why is this valuable? I go into a corner and get rear lockup - all I do is glance at the dash and it is showing me what I needed to see at that moment, but when I am off the brakes, it shows something different that is important at that moment.
But, that is at a price. For me, it really comes down to how many channels and what kind you want. If you are going to spend $5k on sensors then you end up with a low end $7k system. For $10k, you have it all. OTOH, if you are only doing $500 in sensors, then there is a huge total price difference between low end and MoTeC.
#50
Race Car
Thanks for the reply Sunday Driver, that was a very comprehensive reply. Obviously you have become quite intimate with your DAS setup, I know that would be a VERY useful tool in a platform such as a Stohr - no doubt there.
Yeah, I see your point with adding to a low-end system. Admittedly, I am not sure of the capabilities of the Traqmate system and just took a dive after looking at a few other low-end sytems. It was $1,000 and appears that another $200-$300 or so will get me a few options like tach readout and Trackvision software for video, etc.
We'll see when I get it and have three days to read the literature!
Yeah, I see your point with adding to a low-end system. Admittedly, I am not sure of the capabilities of the Traqmate system and just took a dive after looking at a few other low-end sytems. It was $1,000 and appears that another $200-$300 or so will get me a few options like tach readout and Trackvision software for video, etc.
We'll see when I get it and have three days to read the literature!
#51
Three Wheelin'
I have a few spare input channels on my ECU which already logs RPM, TPS, MAP etc and I'd like to add brake pressure to the spare analogue input. Having not logged brake pressures before I am unclear on what pressure range the sensor must cover. I'd appreciate it if someone could advise what the typical upper limits of brake pressure are and a recommendation on a specific pressure sensor would be appreciated.
Thanks,
Thanks,
#52
Addict
Rennlist Member
Rennlist Member
It's not hard to hit 250 bar at the master, with practice.
#54
Three Wheelin'
Thanks Vaughan & Mark. I'm glad I asked the questions as I thought pressures would be under 3000PSI but apparently that is not the case. That particular transducer looks good for future expandability even if I can only use one channel for the time being.
#55
Rennlist Member
Originally Posted by SundayDriver
This is the transducer I have (top of page). Mount with the bleeder up so you can bleed this part of the circuit.
Steve
#58
Rennlist Member
Originally Posted by SundayDriver
I think that SPA part comes with the mounting block and bleeder. As Geoffrey said, simply make the lines to connect.
Steve
#59
Nordschleife Master
Here is a picture of how I installed the brake pressure transducers in my car. The lines are -3 with screw on ends. The transducers are MoTeC parts which use have a -3 female connector and are 0-2000psi rated.
#60
Addict
Rennlist Member
Rennlist Member
Ah... if I'm not horribly mistaken, you have an ABS unit and they're plumbed in after the ABS unit? That'll keep the pressures down.
If you exceed rated pressures on these sensors - do they fail, or just rail-out? If the latter, I'd have no concerns about using them (on a non-ABS car).
If you exceed rated pressures on these sensors - do they fail, or just rail-out? If the latter, I'd have no concerns about using them (on a non-ABS car).