MotionView FSAE Model: Issues Integrating Custom MF-Tyre Coefficients

Shrikar
Shrikar Altair Community Member
in Community Q&A

We’re building a multibody dynamics (MBD) model of our Formula Student electric vehicle using MotionView with the FSAE vehicle library. We’ve successfully removed the default internal combustion powertrain and replaced it with the electric powertrain setup from the commercial vehicle example model.

What we’re trying to achieve:

We want to simulate dynamic events (e.g., constant radius, acceleration) using tire parameters based on our actual FSAE tire data. Our goal is to replace the default example tire data with our own fitted coefficients, calculated using the Magic Formula based on data from the FSAE TTC.

What we've tried:

  • Generated custom MF-Tyre data using a self-developed MATLAB fitting tool.
  • Initially tried to load this as a new tire file but ran into the error:
    "Unknown PROPERTY_FILE_FORMAT", due to missing required chunk:
    PROPERTY_FILE_FORMAT = 'SWIFT-TYRE'
    FUNCTION_NAME = 'tnodelft::DTYRE'
    ROAD_SOURCE = 'TNO'
    N_TIRE_STATES = 5
    USE_MODE = 114
    HMAX_LOCAL = 2.5E-4
    SWITCH_INTEG = 0.1
  • As a workaround, we manually edited the default example tire files and replaced the coefficients with our own.
  • After this, the model loads and runs, but the simulation fails partway through the dynamic events

Is manually editing default MF-Tyre files the recommended approach, or is there a more robust method to import our custom tire data?

Are there any best practices for ensuring stability and convergence in simulations using edited tire data?

Have we possibly missed any available FSAE-specific tire templates or documentation for working with TTC-derived models?

Is there a way to validate that the modified tire file is being parsed correctly by MotionSolve?

Any guidance or sample FSAE tire integration practices would be very helpful. We’d be happy to share snippets of our tire data or the modified tire file if needed.

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Answers

  • Vishvam
    Vishvam
    Altair Employee

    Hello @Shrikar,

    The best starting point for using a tire model in Motionview can be using Altair Fiala Tire models. You will find the FIALA folder in the installation "Tires" directory which you can use for reference.
    Applicability of the FIALA tire model is limited primarily to vehicle handling on smooth road surfaces. It needs very few input parameters to begin with and can be helpful for your usecase.

    Here is the link to understand more on FIALA tire models

    You can also go through the following link to understand different tire models, it's applications and limitations:
    Introduction to Tire Modeling

    Hope this helps!

  • Shrikar
    Shrikar Altair Community Member

    @Vishwam

    Thank you for your response. I'll definitely go through the FIALA tire model as suggested.

    Just to clarify, we already have the tire data from the FSAE TTC dataset, and we've calculated the coefficients based on the Pacejka Magic Formula. The .tir file we've generated includes all the required coefficient blocks, but it's missing specific configuration variables such as:

    PROPERTY_FILE_FORMAT

    • FUNCTION_NAME
    • ROAD_SOURCE
    • N_TIRE_STATES
    • USE_MODE
    • HMAX_LOCAL
    • SWITCH_INTEG

    These were mentioned in my original question, and we’re trying to understand how and where to include them correctly for compatibility with MotionView.

    I can also attach the .tir file we generated if that helps in reviewing the structure.

    TIR file

  • GTT Adam
    GTT Adam
    Altair Employee

    Hi @Shrikar,

    The default values for this heading will suffice for your exploratory needs:

    PROPERTY_FILE_FORMAT ='SWIFT-TYRE'
    FUNCTION_NAME = 'tnodelft::DTYRE'
    N_TIRE_STATES = 5
    USE_MODE = 114 $Tyre use mode switch
    HMAX_LOCAL = 2.5E-4 $Local integration time step (ADAMS only)
    SWITCH_INTEG = 0.1 $Overrule local integrator when set to 0 (ADAMS only)

    The number of tire states should be set to the number of tires in the model + 1, the use mode should be set to your current licensing restrictions and intended simulation needs (shown below), and the other two parameters are for ADAMS only.


    ! USE_MODE specifies the type of calculation performed:
    ! 0: Fz only, no Magic Formula evaluation
    ! 1: Fx,My only
    ! 2: Fy,Mx,Mz only
    ! 3: Fx,Fy,Mx,My,Mz uncombined force/moment calculation
    ! 4: Fx,Fy,Mx,My,Mz combined force/moment calculation
    ! 5: Fx,Fy,Mx,My,Mz combined force/moment calculation + turnslip
    ! +0: steady state behaviour
    ! +10: including relaxation behaviour
    ! +20: including relaxation behaviour (nonlinear)
    ! +30: including rigid ring dynamics
    ! +100: smooth road contact
    ! +200: smooth road contact (circular cross section, motorcycles)
    ! +400: road contact for 2D roads (using travelled distance)
    ! +500: road contact for 3D roads
    !
    ! example: USE_MODE = 434 implies:
    ! -combined slip
    ! -rigid ring dynamics
    ! -road contact for 2D roads
    !

    Hope this helps!

    Adam Reid

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