Tire Friction Estimation Using Data Bins and Grid Segments
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Solution Overview
Problem
Existing methods for determining the coefficient of friction between a tire and road surface in vehicle systems are inaccurate and unreliable, particularly due to variations in tire stiffness and rapid changes in vehicle parameters, limiting their applicability to specific conditions.
Innovation Solution
The implementation of a 'data bin-method' and 'grid-method' for estimating tire-to-road contact parameters, which involve discretizing signal spaces into data bins or grid segments to stabilize and enhance the estimation of tire force and slip relationships, using sensors and filters to update and store parameter values, and applying optimization algorithms to adapt to changing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear recursive estimation algorithms are used to determine the coefficient of friction, then the determination can be performed continuously during driving, but the accuracy and reliability are insufficient due to variations in tire stiffness and rapid changes in vehicle parameters
Solution Approach 1:
The patent segments the continuous parameter space into discrete data bins or grid segments. The signal space defined by tire force and tire slip is divided into multiple intervals, creating a grid structure. This segmentation allows the system to handle variations in tire stiffness and vehicle parameters by localizing estimations within specific bins, thereby improving both accuracy and reliability under varying conditions.
Solution Approach 2:
The patent implements dynamic adaptation by continuously updating the data bins or grid segments based on changing vehicle conditions. The system adapts to rapid changes in vehicle parameters by dynamically adjusting the bin contents and selecting appropriate bins for estimation, making the coefficient of friction determination reliable across different driving scenarios.
2Measurement precision
If tire stiffness is used as an indicator for friction, then surface detection can be performed, but the reliability is limited due to large variation of tire stiffness invoked by other reasons
Solution Approach 1:
The patent segments the tire force-slip parameter space into data bins, allowing the system to distinguish between variations caused by road surface conditions and those caused by other factors. By analyzing patterns within specific bins rather than relying on overall tire stiffness, the system can more reliably indicate friction and surface conditions.
Solution Approach 2:
The patent applies local quality by performing estimations within localized data bins or grid segments rather than using global tire stiffness measurements. This localized approach allows the system to capture specific road surface characteristics while being less sensitive to global variations in tire stiffness caused by other factors.
3Productivity
If the curvature of the relation between tire force and tire slip is interpreted as changed tire stiffness, then estimation can be performed, but misinterpretation occurs for higher tire forces
Solution Approach 1:
The patent segments the parameter space into data bins, allowing the system to distinguish between curvature effects and actual stiffness changes. By performing estimations within localized bins rather than analyzing the overall curvature, the system avoids misinterpretation while maintaining computational efficiency.
Solution Approach 2:
The patent uses partial action by focusing estimation on specific data bins or grid segments rather than analyzing the complete tire force-slip relationship. This partial approach prevents misinterpretation of curvature as stiffness changes while maintaining sufficient productivity for real-time control applications.
Data Source
AI summary
The present invention refers to systems and to methods for determining at least one parameter relating to a tire-to-road contact and/or a relation between a wheel and a vehicle motion. In particular, the present invention refers to systems and to methods for determining the coefficient of friction between a tire and a road surface. For that purpose, the systems and methods according to the invention use new estimation filtering procedures.