Fz0 Nominal or rated load of the Tire TTC and OptimumT ?.

[Ben A]

Hello,

i playing around with the TireData Software OptimumT and the TTC Data. When i do the Model fitting they ask me the static parameter of the The tire i have to insert the Nominal or rated load Fz0 of the Tire.
But i don´t no what i have to insert there can anyone describe me what load that is? Is this the Maximum load during testing, or the minimal? Or another?
look at page 2 on this tutorial: http://www.optimumg.com/docs/OptimumT_Tutorial3.pdf

That would be great thank you.

[BillCobb]

As stated in the Delft Tyre Models User Manual for a Pacejka model solution, Fz0 is a nominal WHEEL load. It could/can be the average of all 4 wheels of your vehicle, or even the average of the left or right wheels. It is just a term used to undimensionalize the raw data for use with the trigonometric functions in the construction of Pacejka (and other) tire model coefficients.

Just for science, you might try to use average front or rear axle weight load to configure the tire data fitting procedure. Yes, you will get slightly different coefficients, but it is theoretically possible to discover a 'better' solution by using a different nominal vertical load for starting the solution iteration.

[HenningO]

Ben,

As Bill explained, the nominal load (Fz0) (and other model constraints such as Pi0 and V0) are used to non-dimensionalize the data.

I would recommend that you pick the highest or second highest tested load as your Fz0. This makes it easier to understand the quality of your fit and how different parameters/coefficients affect it, because the tire model curve at nominal load will overlay one of your raw data sweeps.

For example:
The lateral coefficient PDY1 controls the grip level at Fz0. The PDY2 coefficient affects how the grip level changes with load. Changing PDY1 will change the grip at your nominal load (which is one of your tested loads) but changing PDY2 will not change the curvature at your nominal load, but at lower and higher loads. You can easily try this clicking and holding on the +/- signs next the coefficients in OptimumT.

[Ben A]

Thank you.