A thermomechanical motorsport tyre model applicable for real-time driver-in-the-loop simulations
With the introduction of real-life testing limitations and the advances in the simulation technology, the driver-in-the-loop type simulation environments have gained great popularity over the past decade and become the norm used in the high level of motorsport engineering for driver and vehicle development purposes. Since the tyre is a critical component affecting the overall behaviour of a road-going vehicle, tyre models offering reliable real-time simulation capabilities have therefore gained significant research interest in the field of vehicle dynamics. However, the commercialised nature of the well-developed tyre models currently available in the literature imposes a number of less than ideal limitations and constraints, which makes the implementation of the state-of-the-art methods a challenging and impractical task. The present research work investigates development of practical, high fidelity and computationally-efficient tyre models applicable for real-time simulation purposes, with the ultimate goal of reliable integration into driver-in-the-loop simulation codes. In order to replicate a realistic behaviour of tyres, a physics-based approach was utilised as the main simulation environment, wherein semi-empirical components were introduced to maximise the computational efficiency of the resulting model. Unlike the typical approach of either one-dimensional or three-dimensional discretisation of the tyre, a novel two-dimensional representation of the tyre is proposed herein, where the mechanical behaviour of the tyre is computed over the longitudinal and lateral directions within a finite contact patch contour, with the thermal simulation across the tread width and height being considered in each cycle of wheel rotation. The behaviour of the resulting tyre model was validated by means of both comparison against an industry standard tyre model for combined slip cases and experimental data concerning the lateral characteristics including the velocity-dependent behaviour, with the findings showing error figures less than 3.5% for the shear force predictions. Additionally, through a series of qualitative analyses, the contact patch and thermal simulation behaviour of the model was found to be in good agreement with both theoretical and literature-based findings, which again highlights the high-fidelity characteristics of the model. A novel parameter identification strategy was also proposed, wherein a global optimisation algorithm was used for robust, yet computationally satisfactory results. Finally, the computational efficiency of the resulting model was thoroughly examined through virtual simulation benchmarks, where it was found to be real-time capable even in MATLAB programming environment when subjected to high sampling frequencies.
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