Wet Braking Evaluation via Pressure Distribution Reduction
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Solution Overview
Problem
Current methods for evaluating braking performance on wet road surfaces are costly due to high calculation costs associated with modeling tire and road surface interactions, and existing simulation methods are not suited for combined analysis with vehicle models.
Innovation Solution
A method and device that acquire a tire ground contact pressure distribution and sliding friction coefficient table using a brush model, where the second ground contact pressure distribution is derived by applying the effect of a water film to a first distribution, allowing for the calculation of friction force without a fluid model, thereby reducing calculation costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fluid model is used to model the water film between tires and road surface, then the accuracy of braking performance evaluation on wet surfaces is improved, but the calculation cost increases significantly
Solution Approach 1:
The patent extracts the water film effect from the complex fluid model and represents it through a simplified ground contact pressure distribution model. Instead of modeling the water film as a fluid, the invention applies a reduction coefficient to the ground contact pressure to account for the water film's presence, thereby eliminating the need for expensive fluid dynamics calculations while retaining the essential effect of water on braking performance
Solution Approach 2:
The patent changes the parameter representation from fluid dynamic parameters (velocity, pressure fields) to simplified mechanical parameters (ground contact pressure distribution with reduction coefficient). This parameter transformation allows the system to capture the water film effect through a single coefficient that modifies the pressure distribution, dramatically reducing computational requirements while maintaining evaluation accuracy
2Measurement precision
If a comprehensive tire model and road surface model with fluid model are constructed, then the evaluation accuracy is improved, but the device complexity and calculation resources required increase
Solution Approach 1:
The patent extracts only the essential effect of the water film (pressure reduction) from the comprehensive fluid model, separating this critical function from the complex fluid dynamics calculations. The water film is represented not as a full fluid model but as a modification to the ground contact pressure distribution through a reduction coefficient, simplifying the overall system while preserving the key wet surface effect
Solution Approach 2:
Instead of modeling the water film directly and then deriving its effect on tire contact, the patent inverts the approach by starting with the ground contact pressure distribution and applying a reduction coefficient to represent the water film effect. This reverse engineering approach simplifies the model structure while maintaining the physical accuracy of the wet surface braking evaluation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables accurate evaluation of braking performance on wet surfaces without the need for a fluid model, reducing calculation costs while accurately reproducing ground contact pressure and friction forces, thus effectively assessing braking performance.
Implementation Method 1
calculating a friction force of an entire tire using a brush model having a function representing the ground contact pressure distribution and the sliding friction coefficient table
Implementation Method 2
applying reduction in a ground contact pressure due to a water film intruded between the tire and the road surface
Data Source
AI summary
In a braking performance evaluation method including the steps of acquiring a tire ground contact pressure distribution, acquiring a sliding friction coefficient table, and calculating a friction force of an entire tire using a brush model having a function representing the tire ground contact pressure distribution and the sliding friction coefficient table, the step of acquiring the tire ground contact pressure distribution includes the step of acquiring a first ground contact pressure distribution on a road surface on which no water film is present via actual measurement or calculation and the step of acquiring a second ground contact pressure distribution by applying reduction in a ground contact pressure due to a water film intruded between the tire and the road surface to the first ground contact pressure distribution and using the second ground contact pressure distribution as the tire ground contact pressure distribution used for the calculating.