The creation of the tyre’s digital twin is divided into two phases: the first addresses the tyre geometry, comprehending layers’ thicknesses, meridian profile and user-defined discretization level; the second regards the structural behaviour of the tyre, parametrizing the contact patch variations with varying boundary conditions, starting from images acquired through static or dynamic tests (usually Tekscan or pressure-sensitive paper sheets are adopted).

The output of the tool consists in the parameterization files used within the thermoRIDE model, weaRIDE model and adheRIDE model.

The output of the tool consists in several extra “virtual telemetry” physical channels, including the tires’ dynamics and kinematics, in terms of forces, wheel orientation and slip estimations at each corner. Giving the possibility to estimate the tires’ behavior in each vehicle operating condition, TRICK enriches the standard telemetry datasets with the information concerning the tire interaction characteristics and, therefore, increases the amount of information that track sessions can provide.

Furthermore, TRICK dynamic and kinematic channels per corner enable the employment of the tire physical models, allowing to add further physical features within the enriched dataset, as thermal, wear or transient phenomena. Starting from the outdoor data, so constituted dataset can be exploited to evaluate the dynamic tire characteristics or to properly identify the tire parameters from a multi-physical point of view, with the aim to calibrate the tire models in the widest possible vehicle working conditions range and to reproduce its extremely non-linear behavior within the simulation environment.

The definition of a procedure able to estimate tire forces and slip indices during test sessions can represent a crucial task for many in automotive industry, such as vehicle manufacturers, vehicle dynamics engineers and tire production companies. TRICK has been exploited as both a development tool to be employed in the earliest prototyping phases and as a data analysis advanced tool for experimental activities carried out with high performance vehicles during the setup preparation sessions, since it significantly increases the amount of crucial data available to understand how the vehicle and its tires are performing, taking strategic decisions for vehicle and tires setup development.

The innovation represented by the TRICK is in its novel approach in tire characterization and in tire models correlation with outdoor vehicle data, since it enables the understanding of the dynamic response of the whole vehicle and of the tires by means of simple and smart outdoor track sessions, carried out employing the vehicle as a moving lab, with no need of bulky and expensive tire test benches.

Silver medal at Vehicle Dynamics awards 2014

Starting from the raw data, RIDElab enables smart procedures for the elimination of the outliers, reliable evaluation of camber and load effects, leading the user to a robust identification of both the Pacejka’s Magic Formula based and other mechanical tire interaction models, taking also into account of their variations towards complex multi-physical of tire/road contact phenomena. The effects induced by thermal and wear phenomena on frictional and structural tire behavior, including the discrimination between the effects due to tread layers and carcass temperature, to compound degradation, road roughness influence and polymers viscoelastic characteristics, can be smartly identified and validated with the RIDElab tool.

RIDElab is moreover adopted by our partners, to:

The model is able to provide real-time tire temperature distribution, with particular reference to the deep layers usually not reached by measurement instruments, accounting for the dissipative phenomena induced by cyclic deformations and for the effects due to thermal exchanges with external environment.

Moreover, thermoRIDE is preliminarily characterized by means of a specific “LAB” version, able to identify thermal (density, conductivity and specific heat) and structural characteristics (SEL characterization and contact patch area measurement at different values of vertical load, inflation pressure and camber angle) with proprietary totally non-destructive methodologies.

Considering the tire as a thermodynamic system, the heat transfer mechanisms have been physically modelled, accounting for:

Depending on the complexity and on the geometry, the tire structure is discretized, guaranteeing hard real-time performance, with up to 6 radial layers (from external tread to inner liner) and 16 lateral ribs (in our motorcycle thermoRIDE version), with peculiar physical characteristics. The layers reproduce the tire composite matrix structure, comprising tread external surface, tread core, tread interface with belt, carcass inner liner and inner air, allowing to better understand the thermodynamics of the whole tire in terms of grip and stiffness variations and in the definition of the optimal thermal range. The developed thermodynamic tire model is based on the resolution of the diffusion equation of Fourier applied to a three-dimensional domain, whose formulations have been specifically coded for an optimized computation.

With the aim to let thermoRIDE users being able to autonomously parameterize and manage the tire digitalization, a specifically developed tool, called RIDEtool, is provided to the customers.

Tire Technology of the Year, together with adheRIDE, at Hannover Tire Technology Expo in 2018

Among these, the influence that, for example, the thermal conditions of the different tread layers have on friction and on stiffness characteristics, is particularly significant and definitely not negligible in case a full reliability of the vehicle dynamics simulations is required in both motorsport and passenger applications.

To take into account of the crucial effects related to grip/temperature relationship, to tire degradation state and to the completely variable boundary conditions under analysis, the employment of an innovative version of the widely adopted Pacejka’s formulation, able to run in parallel with thermal, wear and road multi-contact models, becomes a necessity for applications requiring high compliance with the consolidated MF approach.

adheRIDE represents an advanced Pacejka-based interaction model, whose parameters are no more static or fixed throughout the entire run, but are variable with external physical dependencies.

An example of the importance of the interaction between adheRIDE advanced MF and other physical tire models can be easily deduced analyzing the impact of tire tread core and carcass temperature quantities, not available from common onboard sensors (but provided by thermoRIDE tire thermal model), that deeply modify the tire dynamic behavior. The same can be said for the effects due to wear, to road roughness scales and to tread compounds viscoelasticity, identified by RIDElab and parameterized in adheRIDE for their reproduction in real-time simulations, laptime predictions and model-based data analysis. 

With the aim to let adheRIDE users being able to autonomously parameterize and manage the tire digitalization, a specifically developed tool, called RIDEtool, is provided to the customers

Tire Technology of the Year, together with thermoRIDE, at Hannover Tire Technology Expo in 2018

adheRIDE model can be used, as a “middle layer” between wheel hub and virtual road engine, in both offline and DiL simulative applications. In a basic scenario related to standard MF approach, adheRIDE can interact with road by a single contact point.

Thanks to threedeeRIDE model, deputed to the extension of the standard MF model to higher frequency domain, it can interact with the road mesh through a multi-contact mechanic, in a double way:

• for pure handling applications, by means of a kinematic low-frequency interface (which consists of a double-cam quasi-static approach whose dimensions depend on the tire’s state),
• for ride & handling simulations, through a high-frequency interface adopting a SWIFT-evo modeling, considering both the contact patch and the out-of-plane belt dynamics and all the other multiphysical effects (temperature, wear, viscoelasticity, etc.) reproducing the real contact feeling between the vehicle and the external environments in hard real-time applications. 

Such solution provides, thanks to the physical modelling of the effects involved in the contact between the tire and the environmental texture, the continuous local contact height and the orientation of the tire contact patch normal vector. They are used to enhance the feelings and realism of the driving experience, and to properly evaluate the kinematics at the tire/road interface, taking into account of all the phenomena connected to the multiphysical tire state, as tread and inner temperature, internal inflation pressure and the wheel alignment configuration.

threedeeRIDE aims to extend the range of tire dynamics validity of the usual single-contact-point models in the frequency domain, both within the lower frequencies concerning the tire interaction with the large obstacles (as kerbs, bumps, pot holes, …) and the higher frequencies regarding the power spectral density of the road surface texture, enabling no more just handling analysis and simulations, but ride too. Moreover, the model provides the normal vector to the plane representing the 3D orientation of the tire footprint, along which the tire-road interaction loads are transferred to the vehicle suspension system, allowing a proper design and structural sizing.

The model is able to interact with any kind of road mesh, coming from ride scenarios, high-definition track 3D scans and driving simulations, calculating the trajectory of the wheel hub when the tire overcomes an obstacle on its path, or runs on the macro and micro texture of road asphalt.

threedeeRIDE generates its output taking into account the variations induced in the contact patch shape and in the tire carcass deflection due to vertical load, inflation pressure, inclination angle and speed. Such variables are taken as an input by the model, that is physically parameterized by previous analysis on the footprint shape and extension under various working conditions, obtained by means of proper test campaigns carried out at our laboratories.

threedeeRIDE model can be coupled with adheRIDE or with any other third-parties tire interaction model to extend the range of validity of the contact patch formulation to a higher frequency domain. A specific multi-contact module is designed to interface with any road engine determining a correct normal direction and equivalent plane for the forces’ propagation from the contact patch to the wheel hub and to properly model tire/road interaction encountering micro- and macro-asperities, evaluating the dynamic information regarding the generalized load and torque vectors transmitted to the suspension. The road can be queried with two different purposes:

• for handling applications, linkable by means of a simplified kinematic low-frequency interface (which consists of a double-cam quasi-static approach whose dimensions depend on the tire’s state)
• for ride & handling simulations, linkable by means of a high-frequency interface adopting a SWIFT-evo modeling, considering both the contact patch and the out-of-plane belt dynamics with all the intrinsic multiphysical effects (temperature, wear, viscoelasticity, etc.) reproducing the real contact feeling between the vehicle and the external environments in hard real-time applications

Such a specific modeling allows to discern two important mechanisms: the mechanical abrasion of the compound due to the interaction with the road asperities (wear is proportional to the work done by abrasive friction forces arising at the contact interface) and the chemical degradation of the rubber linked to the thermal fatigue which induces the continuation of the vulcanization process and leads to both the gradual hardening of the compound and the reduction in peak friction capability.

With the aim to let weaRIDE users being able to autonomously parameterize and manage the tire digitalization, a specifically developed tool, called RIDEtool, is provided to the customers