Tire modeling for functional safety compliant vehicles

By Paul van Straten
Developing functional safety compliant vehicles
Mf-Tyre/MF-Swift 2021.1 release

MF-Tyre/MF-Swift is now classified according to ISO26262, making the tool suitable for developing functional safety compliant vehicles. Further, release 2021.1 brings increased fidelity in steering simulations and a safe exchange of tire model parameters.

MF-Tyre/MF-Swift ISO 26262 qualification, supporting the development of safety compliant vehicles

On the road towards autonomous driving vehicles more and more safety critical systems are introduced. The developments of such systems are typically supported by software tools. To ensure these systems are safety compliant it is important that one can be confident about the adequate functioning of these software tools. Therefore, the ISO26262 recommends qualification of the (software) tools used in the development process of such systems.

The MF-Tyre/MF-Swift product has been assessed and demonstrates the highest-level op tool confidence, namely a classification TCL1, according to ISO 26262:2018. A certificate has been obtained from the Certification Body for Functional Safety SGS-TUV Saar GmbH.

Improvements for standstill steering maneuvers

Predicting tire behavior when steering the wheels at standstill is important for the design and dimensioning of steering systems. To represent the tire forces and moments under these conditions a dedicated sub-model is used in MF-Tyre/MF-Swift. In the 2021.1 release the following improvements are included:

  • The model robustness for noise inputs (e.g. coming from sensor signals on HiL setups) is increased
  • The rubber relaxation properties are explicitly modelled
  • The saturation of the tire aligning moment is modelled dependent on the vertical load
  • The changes of inflation pressure are explicitly modelled

With these improvements the accuracy and robustness are significantly increased.

Supporting a safe exchange of tire model parameters

With further digitalization of the vehicle development process comes the need to exchange Digital Twins of the vehicle and its components. Zooming in on tire modeling at OEMs, this exchange happens internally between different development departments and externally with suppliers. The latter may be an exchange of Digital Twins of tire prototypes between OEM and tire manufacturers, but also between OEMs and their TIERs, such as steering- or braking system suppliers.

In many of these situations the tire model parameters that are exchanged should not be readable to the receiving party. The two main reasons are that:

  • Confidential information is exchanged, therefore exact parameter values should not be revealed
  • The sending party wishes to prevent that the receiving party changes the parameter values

MF-Tyre/MF-Swift 2021.1 comes with an obfuscation tool to support above use cases. With this tool the MF-Tyre/MF-Swift TIR-files can be obfuscated, meaning that end users can no longer read nor change parameters. The user settings present in the TIR-files remain readable and editable.

Product compatibility and availability

MF-Tyre/MF-Swift is directly available with all major vehicle simulation packages. Release 2021.1 is now available in combination with Matlab and MSC Adams. Throughout the coming months MF-Tyre/MF-Swift v2021.1 will also be available with Siemens Simcenter AmeSim, Siemens Simcenter 3D Motion, IPG CarMaker, VI-CarRealTime, Mechanical Simulation Corp CarSim, Dassault Simpack, Altair MotionSolve, Modelon Vehicle Dynamics Library and others.

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This article first appeared on the Siemens Digital Industries Software blog at