"I saw a lot of hysteresis on raw data graph i.e. for IA=4° tests pass trough SA=0 four times and 2 curves indicates a lot of FY+ and the 2 others indicate approximately 0."

All of the curves pass through zero four times. That's how the tests are run, watch the test videos. They pass each tire through zero four times in order to get as much data as possible in that area, so they can approximate the cornering stiffness as accurately as possible.

As for the problems with the Goodyear tire I agree with you that its camber response doesn't seem right. MRA is aware of the problems and have scheduled time to fix them.

I hope that helps.

Hi VinceL,

Thanks for the details.

In fact, for the test, I know how they are run... my point was more about FY value of these curves. There is effectively 4 curves that pass through zero but 2 of these curves give a FY value of about 30 lbs for lateral force while the 2 other curves give a lateral force near to zero (which is what is expected). I wonder what caused this difference.

If MRA is aware of the problem, do you know when we should expect to have some news from them? How do you know the are aware of the problem? Is there any place where the known problems are listed?

Thanks!

Hi all, I'm developing a vehicle dynamics model of our Formula Student car, using MatLab Simulink (SimMechanics) I would like to incorporate Pacejka's tyre model into this eventually. Does the Tyre Test Consortium data give Pacejka coefficients of the tyres?

Secondly I have a problem; my university wont fund the cost of the FSAE tyre data until I have a model that I can prove will work with pacejka coefficients. So I wonder if anyone has pacejka data for a somewhat 'random' tyre that they would send me? Just to get a working model with Pajecka coefficients that are roughly the right orders of magnitude...

Jonny_B, I believe you can find Pacejeka coeffiecients of a tire just using Google. In fact I believe a set of coefs. are given in RCVD. And yes Pacejka coeffiecents are given from the tires, although I personally prefer the MRA Non-dimensional model and if you are writing your own code, I'd use that.

On another note, is there anyone else that would like to see a "closed" forum where schools that have bought the data can discuss it and post plots and figures? Maybe that is something that can be organized in collaboration betweend FSAE.com and Dr. Kasprzak/Dr. Milliken? I mean on this forum we are able to dicuss nearly any aspect of the cars. I don't know about you, but I've learnt quite a lot from these forums, why shouldn't we be able to learn about tires as well?

Yes, a closed forum would be great. It would be easier to discuss about data if we can post graph.

Hi all,

I owe several people e-mail replies. I've been traveling and am swamped with paid work right now, but I hope to catch-up on my FSAE TTC correspondence in the next week or two.

OK Can someone tell me about this non-dimensional tire model that is included with tthe tyre data? Is it a 'combined' model such that lateral slip angle will also affect the longitudinal force? I need to write the tire model into MatLab code for my dynamics model - is there any problem with doing this? Also are we provided with mathematical code for the easy generation of tire curves?

We will be purchasing this soon if it does meet our requirements.

Thanks,

Jon.

Jon, a MATLAB script that uses normal load, inclination angle, slip angle, slip ratio as input and gives you lateral and longitudinal force is included with the data. The non-dimensional model is described in RCVD.

The same script can be used to create tire curves as well.

OK thants good. Finally, how long will it take for the disc to be posted to us (need it ASAP), and are we directly given all of the coefficients that we need to construct tire curves for each of the tested tires?

Thanks,
Jon.

All the coefficients are in *.mat files called by the script. Each tire has its own *.mat file.

A few posts ago someone mentioned creating a private forum for FSAE TTC members only. Does anyone know how we could set this up? I like the idea.

For me, I'll have updates to the MRA model to ship shortly, and SES has also sent me a document clarifying sign conventions that I'd like to get to everyone. Posting in a secure forum would be the easiest way to distribute these since the files will not be large.

I'd like to see all the FSAE students be able to talk more openly about their data and models. Let me know if you have any ideas on setting up a secure site. Seems like the hard part will be verifying that those logging on really are from a member school....

Oh, and thanks everyone for respecting the terms of the FSAE TTC agreement (not posting data, etc.) We've had almost no issues. You'll have plenty of legal agreements to abide by and proprietary knowledge to protect in your upcoming careers--it's nice to see that our agreement has been so well-respected.

About the private forum, I guess FSAE TTC has an email contact to all partcipating schools, by sending login info to that adress would be one way.

I don't know who manages this site? Adding another password protected forum alongside all the existing ones makes most sense IMO.

Hi,

Does anyone know what to do?
I got this error using the ExpansionType 5 with any of round 3 tire data file:


??? Error using ==> rdivide
Matrix dimensions must agree.

Error in ==> ...\fromMillikenResearchAssociates\expand_mrandim.p>expand_mrandim at 792


Error in ==> call_mrandim at 208
MZ = expand_mrandim([5,units],NDIM5,[FZ,SA,IA,0,mu]); % Call to MRA Nondimensional Tire Model



And I got this error using metric units with any of round 3 tire data file:

??? In an assignment A(I) = B, the number of elements in B and
I must be the same.

Error in ==> ...\fromMillikenResearchAssociates\expand_mrandim.p>expand_mrandim at 741


Error in ==> call_mrandim at 104
FY = expand_mrandim([4,units],NDIM4,[FZ,SA,IA,0,mu]); % Call to MRA Nondimensional Tire Model


We would very thankful if someone could help us.

Thanks!

Matthias_W,

That's a known error in dataset #3, as Dr. Kasprzak (of the FSAE TTC) mentioned earlier in this thread, they are working on a fix for this.

Regarding a private forum for FSAE TTC members:

If there is a student who would like to volunteer his/her time to set-up and maintain such a forum the consortium leadership would be interested in hearing from you. Please e-mail me directly. We'd like to establish the position of "Student Associate", similar to the position Denny Trimble occupied when the consortium was founded (and before he graduated). Duties would include:

+ Establishing a private forum for the FSAE TTC
+ Establishing access to this forum for consortium members
+ Maintaining the forum membership list as new schools register for the consortium and as contacts at schools are updated. This happens regularly.
+ Watch for students openly posting data outside of the private forum and pursue corrective action

We have a contact person and e-mail for all the schools, so this can be used to establish sign-in rights and password protection. The only issue there is that some of the contacts are a few years old now and may no longer be relevant. These will need to be updated.

In return, you will be making a valuable contribution to the FSAE community, will have even more work to do and will exprience occasional throbbing headaches because of it. You'll also be listed on the FSAE TTC website as the Student Associate and the consortium leadership (and member students) will say all sorts of nice things about you--assuming you do a good job.

Finally, we're open to a discussion on whether or not this position merits a small monthly stipend. The directors are all-volunteer, but this may be a large enough and important enough task to offer lunch money to the student who jumps onboard. What do you students think?

I'm looking forward to hearing from anyone who's interested.

A question about the non-dimensional model and slip angle peaks.

If you do not see a peak for a slip angle sweep at a given load then you will not know the peak coefficient of friction for that load. In this case, how would you go about normalizing that slip angle sweep?

Hi,

I'm very interested to know how other UK teams managed to pay for this data..? It seems they wont accept any form of payment that my university can provide!

Thanks,

Jon.

What's going on with the MRA update?

I'm also wondering about the MRA update. Did anyone else notice that the slip angles and slip ratios seem to have the wrong sign in the Goodyear Round 3 data. I didn't have any problems with the Round 1 nondimensional solution, but round 3 is tearing me up.

Also, any more word on the private forum?

VTSpensh: it is just a bug and i had mailed Mr Milliken some time back. he said he would get it solved as soon as he has time...