pacejka MF5.2 /2002 equations

[Ben A]

Hello,

i´m thinking to build up some Excelspreadsheets for pacejka MF5.2 coef. To plot FY vs. SA and so on. But at the Moment i strungel a little bit where to find the rigth pacejka MF5.2 or 2002 equations. With the ttc Data there is a PDF with the Stackpol pacejka 96 equations but im not sure what is the differents and additional coef. and equations.

Is there someone who can send me the equations?

Thank you

[Claude Rouelle]

And you are?

[exFSAE]

Usually wouldn't care that much to throw this much of a bone, but... Google: adams tire pdf pac2002

[slicktop]

I second adams help file - it is a great reference. Also, there is an explanation in HBP's book.

[Zac C]

You want chapter 4.3.2 of pacejka's book. A google search turned up this on the front page:

http://www.rmcet.com/lib/E-Books/Mech-auto/Tyre_and_Vehicle_Dynamics.pdf

[slicktop]

So how do you pronounce Pacejka? I've always wondered. I think it's pa-sedge-ka.

[Zac C]

So how do you pronounce Pacejka? I've always wondered. I think it's pa-sedge-ka.

pa - jay - ka

[Ben A]

Thank you all for your replys.

@Mr. Claude, sorry i´m Ben i´m a Member of the OWL Racing Team from Germany, we were just new to the TTC and Tiremodeling.

[Viv]

Hi everyone. I am Viv from University of Toronto. I was looking to create MATLAB simulations which require Tire Models specifically the Pacejka 2002 tire models. I have fit models using Optimum Tire. Now I was looking to program the model equations into Matlab and use these coefficients to generate forces for simulation. My resource for the equations is an ADAMS Tire pdf explaining the pac2002 models.

The problem: the tire curves generated by my simulation are wrong when camber effects are included. At zero camber I get curves that look identical to those generated by Optimum Tire. Upon adding any amount of camber the curves have the same general trend but are not identical to those plotted by Optimum Tire. I have attached the pdf of the equations, and two images showing the optimum tire curves and my curves. In the pdf for steady-state lateral, there is an equation for camber stiffness which is not used in any of the other equations (could this be a problem)?


701702703704

[Tim.Wright]

Viv,

The first thing to check in all this tyre modelling business is the units and reference system.

I can't read the equations on my dumb phone at the moment but I have seen that the Adams implememtation is different to what is in pacejka's book. I assume (maybe Claude can confirm) that optimum T uses the formulation in Pacejka's book. If you can get hold of that book (tire & vehicle dynamics) you can do a comparison of the 2 formulations.

[SNasello]

Viv, if you are using optimum tire why don't you just use the COM add in? There is an example of it included with OptimumTire.

In addition if you look on the TTC forum I have posted there a block set to use the com add in with simulink.

As for your qeustion, the standard input for camber and slip angle in pacejka is in radians. This could be causing your strange behaviour.

[Claude Rouelle]

As it is the case to 95 % of the questions our software support team received from students, the answer to this question is in the OptimumTire software help file.

There are 2 rules related to software use
1. You cannot make a software work unless you read the user manual
2. Nobody, and certainly not students, want to go though the pain of reading the user manual.

Up to you now....

[slicktop]

Whether using Optimum T or putting together a computer desk from Ikea, the first step is always to throw out the instructions. :-)

[Viv]

Hi Guys. Sorry I haven't been back with an update. I have been busy.

Thanks for your response Claude. I did in fact look at the manual and it does mention that the equations implemented are from the first version of the Tire and Vehicle Dynamcis from 2002. As I didn't have a copy of the book I was trying to confirm whether the equations from Adams were the same.

Thanks Tim. As you mentioned the implementation between Adams and the book was slightly different and I also noticed I was missing the implementation of one of the first equations (it calculated alpha_star from alpha using tan(alpha)).

In conclusion, I finished the lateral force plotter and also finished the aligning torque plotter.

And Slicktop, its often more fun to put together things without the manual, especially those Ikea desks. :)