Wet-Surface Tyre Model Using Sigmoid Grip Prediction
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Solution Overview
Problem
Existing vehicle simulation models based on the Pacejka Magic Formula fail to accurately predict tyre behavior on wet surfaces, leading to inadequate correlation with experimental results.
Innovation Solution
A computer-implemented tyre model using a sigmoid function dependent on vertical tyre load and longitudinal tyre velocity to calculate load-dependent friction coefficients, providing a more accurate prediction of tyre grip on wet surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Pacejka Magic Formula model is used for vehicle simulations, then the model is simple and widely applicable, but it fails to accurately predict tyre behavior on wet surfaces
Solution Approach 1:
The patent modifies the Pacejka Magic Formula model by introducing a speed-dependent friction coefficient that changes based on longitudinal tyre velocity. This parameter change allows the model to accurately capture the reduction in tyre grip at higher speeds on wet surfaces, resolving the contradiction between maintaining model simplicity and improving prediction accuracy for wet conditions
Solution Approach 2:
The patent transforms the static friction coefficient in the Pacejka model into a dynamic parameter that varies with longitudinal velocity. This dynamic adjustment enables the model to adapt to changing speed conditions on wet surfaces, improving reliability without requiring a completely new model framework
2Measurement precision
If physical testing is conducted to validate tyre behavior on wet surfaces, then accurate experimental data is obtained, but the process is time-consuming and resource-intensive
Solution Approach 1:
The patent creates a computational copy of physical tyre testing through the enhanced Magic Formula model. By implementing a speed-dependent friction coefficient, the model reproduces wet surface tyre behavior accurately without requiring repeated physical experiments, thereby maintaining measurement precision while eliminating time losses associated with physical testing
Data Source
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AI summary
A computer-implemented method of predicting the behaviour of a vehicle tyre on a wet road surface is disclosed. The method comprises: providing a computer-implemented tyre model; inputting a vertical tyre load (Fz) and a longitudinal tyre velocity (Vx) to the tyre model; using the computer-implemented tyre model to calculate a predicted tyre grip in terms of the load-dependent friction coefficient (µx, µy) based on a sigmoid function that is dependent on the vertical tyre load (Fz) and on the longitudinal tyre velocity (Vx); and outputting the predicted tyre grip from the computer-implemented tyre model.