Suggestions for Tire and DAQ papers?

[monoposto]

I looked through the sticky, and i've been searching through SAE on tire modelling papers and how to set-up your car to get accurate data. But honestly asking people that may have read something beneficial is a lot more time efficient. So..... SAE Papers that have solid information in them would be great!

Thanks in advance!

mono

[exFSAE]

Tire modeling is a deep dive down the rabbit hole. Why not use the tire models already available through the TTC? Maybe a later date you could look into doing your own.

[jlangholzj]

Originally posted by exFSAE:
Tire modeling is a deep dive down the rabbit hole. Why not use the tire models already available through the TTC? Maybe a later date you could look into doing your own.

I'd agree but might as well start learning right?

What exactly are you trying to find? lateral loading vs down-pound for cornering? Straight line accel/breaking. I mean you're kind of leaving this pretty open.

Also if you're not a member of the TTC and are serious about learning more on this, I'd suggest becoming one. Edward's a member here but also a very frequent member on the TTC forum and he's bar-none when it comes to tires and chassis.

[exFSAE]

Originally posted by jlangholzj:
I'd agree but might as well start learning right?

Not necessarily. It's a question of what's a valuable use of your time. Not everything is.

Honestly I see diving into tire model fitting at the FSAE level as high investment and minimal return - even negative return if you don't have expert level knowledge on what's right and what isn't and then start making decisions based on questionable results. If it were me I'd use off-the-shelf deliverables from TTC and roll with it. Maybe do some QA on the supplied fit curves.

[BillCobb]

And in case you were unaware, SAE papers are not free for the asking.

Join the TTC (its only money), get tire representations ready to use, get suggestions on how to roll your own, get methods to create your own fits to traditional models, get examples of how to use tire models in vehicle simulations, get results. This is not a science class, its engineering.

Anteposto.

[js10coastr]

Not an SAE paper, but this is a pretty good starters' book for data acquisition.

http://www.amazon.com/Analysis...sition/dp/076801655X (http://www.amazon.com/Analysis-Techniques-Racecar-Data-Acquisition/dp/076801655X)

[Zac]

Originally posted by js10coastr:
Not an SAE paper, but this is a pretty good starters' book for data acquisition.

http://www.amazon.com/Analysis...sition/dp/076801655X (http://www.amazon.com/Analysis-Techniques-Racecar-Data-Acquisition/dp/076801655X)

The book Data Power is also pretty good for getting started. It has been out of print forever and used copies are very overpriced. There's a pdf floating around somewhere in the bowels of the internet though.

[Charles Kaneb]

Originally posted by BillCobb:
And in case you were unaware, SAE papers are not free for the asking.

Join the TTC (its only money), get tire representations ready to use, get suggestions on how to roll your own, get methods to create your own fits to traditional models, get examples of how to use tire models in vehicle simulations, get results. This is not a science class, its engineering.

Anteposto.

At most US universities, SAE papers are right there in the library. I know they are at TxA&M.

[jlangholzj]

Originally posted by Charles Kaneb:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by BillCobb:
And in case you were unaware, SAE papers are not free for the asking.

Join the TTC (its only money), get tire representations ready to use, get suggestions on how to roll your own, get methods to create your own fits to traditional models, get examples of how to use tire models in vehicle simulations, get results. This is not a science class, its engineering.

Anteposto.

At most US universities, SAE papers are right there in the library. I know they are at TxA&M. </div></BLOCKQUOTE>

either that or we ask our advisor and they can get the papers for us. Any uni should have easy access to them

[monoposto]

Apologies, have been busy with classes as of late.

@Bill, agreed. I am a part of the TTC however the volume of traffic leaves much to be desired. At least compared to this forum which get's quite a bit and a reasonable amount of knowledgeable people, not that the TTC doesn't. Just as well, my university is allowed to attain SAE papers via Illiad. Or so they tell me. I may cross post this over to the TTC as well.

On to the topic at hand. I should've elaborated more to make my reasoning on this clear. I was very vague....

My reasoning behind this is that I want to set up some sensor's on a track car so as to measure the forces at the tires. Once I have that, my plan was to just roll my own tires so to speak to where I can understand Pacjeka (what im most familiar with) or do some sort of curve fit that is at my level of understanding tires. The problem is, I don't know where to start with this other than possibly setting up some strain gauges on the a-arms/possibly uprights. Hence the tire paper's and DAQ.

From this move on to some more complex simulation etc... Honestly this is my hobby, I LIKE doing and reading stuff like this. So have no intention of being a professional race engineer just a damn good weekend racer that understands the vehicle dynamics a level above the competition. http://fsae.com/groupee_common/emoticons/icon_wink.gif

P.S. I have been looking at some DAQ books and I saw one that was around $700....USED!!!! http://fsae.com/groupee_common/emoticons/icon_eek.gif Being a poor college student, I will have to wait on that one. And I appreciate the feedback!

[jlangholzj]

Look into TTC. There's some explaining of the Pacjeka models as well as some code on fitting curves to find them. I know, I stole snippets from bills code, modified it and put it up as well http://fsae.com/groupee_common/emoticons/icon_wink.gif

TBH, I don't know much outside my aero / suspension guys telling me what to do, but once they explain what they're looking for its very apparent what benefits there are to learning about it.

Before you go all crazy and start taking in Daq on tires, I'd get VERY comfortable with using matlab and processing the TTC data available. Little bit of work and you can get something like this:

http://i260.photobucket.com/albums/ii35/jlangholzj/28471318-f6f4-4dbf-9ea9-c87fb137e1fb_zpsd4773fa1.jpg


I removed the lateral forces so as not just to throw this information out there, most of the important stuff was left out.

This was for SS cornering and I'm working through my code to make sure it works for accel/braking as well. The script has a gui that prompts you for the file, how you want to evaluate it and what you're looking for. ie what vs what.

doing all of this is a bit of a handfull in itself.

[DougMilliken]

Originally posted by jlangholzj:
... I removed the lateral forces so as not just to throw this information out there, most of the important stuff was left out.
Nice to see that you are following the TTC data license. For anyone new to TTC, this can be found on the public page,
http://www.millikenresearch.com/fsaettc.html Heading: "USE OF THE DATA – FSAE TTC LICENSE AGREEMENT"

TTC members have access to the private forum where it is acceptable to discuss the actual data.

[exFSAE]

As if tire modeling wasn't a challenge enough, if you want to extract model curves from track data... that can be quite a challenge (if not entirely impractical), as the data is very sparse.

[MCoach]

Strain gauge all the things. http://fsae.com/groupee_common/emoticons/icon_wink.gif

http://sphotos-b.xx.fbcdn.net/hphotos-snc6/277415_213076328744700_8297997_o.jpg

[monoposto]

Has anyone read this sae paper? 2009-01-0434: http://papers.sae.org/2009-01-0434/

So, since you guys have asked more questions on why I want to do this, it has forced me to sort of refine my questions a bit more. So.....

Any recommendations on threads/sae papers regarding pacjeka curve fitting and sort of a method for going about it?

[ben]

Originally posted by monoposto:
Has anyone read this sae paper? 2009-01-0434: http://papers.sae.org/2009-01-0434/

So, since you guys have asked more questions on why I want to do this, it has forced me to sort of refine my questions a bit more. So.....

Any recommendations on threads/sae papers regarding pacjeka curve fitting and sort of a method for going about it?

I've been using OptimumT for the past few years, but prior to that I wrote my own fitting routines in Matlab using the optimisation toolbox. You can use Excel Solver to be honest too.

The general approach is this:

Select best guess set of coefficients as a start point
Calculate force and moments using these coefficients
Calculate the error between your forces and moments and the values calculated from your model
Adjust the coefficients to minimise the error using a solver (Excel, Fminsearch, Fmincon, etc)

As for the order in which to do things, this generally works:

Fit pure Fy
Fit Mz
Fit Fx and Fx combined at the same time
Fit Fy combined

At each stage using the coefficients from the previous step, to improve the fit.

Ben

[jlangholzj]

Originally posted by ben:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by monoposto:
Has anyone read this sae paper? 2009-01-0434: http://papers.sae.org/2009-01-0434/

So, since you guys have asked more questions on why I want to do this, it has forced me to sort of refine my questions a bit more. So.....

Any recommendations on threads/sae papers regarding pacjeka curve fitting and sort of a method for going about it?

I've been using OptimumT for the past few years, but prior to that I wrote my own fitting routines in Matlab using the optimisation toolbox. You can use Excel Solver to be honest too.

The general approach is this:

Select best guess set of coefficients as a start point
Calculate force and moments using these coefficients
Calculate the error between your forces and moments and the values calculated from your model
Adjust the coefficients to minimise the error using a solver (Excel, Fminsearch, Fmincon, etc)

As for the order in which to do things, this generally works:

Fit pure Fy
Fit Mz
Fit Fx and Fx combined at the same time
Fit Fy combined

At each stage using the coefficients from the previous step, to improve the fit.

Ben </div></BLOCKQUOTE>


matlab can do all that for you with the "csaps" function. Works a lot like the "plot" command where you give it x-coordinates and y-coordinates that then return the fit curve.

I'd really suggest using matlab, excell seems....painfull. I mean if its all you've got then i guess thats all you can do. The main benefit of a program like matlab is the use of loops.

Also if you don't have matlab, get ubuntu (free) and download octave (free) which is basically matlab with a different gui.

[Spetsnazos]

Originally posted by jlangholzj:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ben:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by monoposto:
Has anyone read this sae paper? 2009-01-0434: http://papers.sae.org/2009-01-0434/

So, since you guys have asked more questions on why I want to do this, it has forced me to sort of refine my questions a bit more. So.....

Any recommendations on threads/sae papers regarding pacjeka curve fitting and sort of a method for going about it?

I've been using OptimumT for the past few years, but prior to that I wrote my own fitting routines in Matlab using the optimisation toolbox. You can use Excel Solver to be honest too.

The general approach is this:

Select best guess set of coefficients as a start point
Calculate force and moments using these coefficients
Calculate the error between your forces and moments and the values calculated from your model
Adjust the coefficients to minimise the error using a solver (Excel, Fminsearch, Fmincon, etc)

As for the order in which to do things, this generally works:

Fit pure Fy
Fit Mz
Fit Fx and Fx combined at the same time
Fit Fy combined

At each stage using the coefficients from the previous step, to improve the fit.

Ben </div></BLOCKQUOTE>


matlab can do all that for you with the "csaps" function. Works a lot like the "plot" command where you give it x-coordinates and y-coordinates that then return the fit curve.

I'd really suggest using matlab, excell seems....painfull. I mean if its all you've got then i guess thats all you can do. The main benefit of a program like matlab is the use of loops.

Also if you don't have matlab, get ubuntu (free) and download octave (free) which is basically matlab with a different gui. </div></BLOCKQUOTE>

You can write macro's in VBA

but yeah, I rather use Matlab