Road Surface State Detection Using Slip Ratio Regression
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Solution Overview
Problem
Existing methods for determining the state of a road surface during vehicle travel face challenges in accurately calculating the regression coefficient between slip ratio and driving force, especially when the driving force has minimal variation, leading to unstable determination of road surface conditions.
Innovation Solution
A determining apparatus and method that calculates the regression coefficient based on a large number of data sets of slip ratio and driving force when variation is sufficient, and uses a pre-obtained intercept when variation is low, ensuring stable determination of road surface state by adjusting the slip ratio calculations based on turning radius and lateral acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the regression coefficient is calculated from data sets during periods when driving force does not change much (e.g., constant velocity on descent), then the calculation can be performed continuously, but the accuracy of road surface state determination deteriorates
Solution Approach 1:
The system pre-calculates and stores the intercept of the regression line during periods when driving force varies sufficiently. This preliminary action allows the system to maintain continuous determination capability while ensuring accuracy by using pre-stored reliable intercept values when current data lacks sufficient variation.
Solution Approach 2:
The intercept acts as an intermediary parameter that decouples the determination process from the requirement of continuous driving force variation. By storing and reusing intercept values obtained during suitable periods, the system bridges the gap between periods of sufficient and insufficient data variation.
2Measurement precision
If the regression coefficient is calculated only during periods when driving force varies significantly, then the accuracy of road surface state determination is improved, but the continuity and responsiveness of determination deteriorates
Solution Approach 1:
The system performs preliminary calculation of the intercept during periods when driving force varies sufficiently, storing it for future use. This allows continuous determination without waiting for suitable periods to occur, reducing time loss while maintaining accuracy.
Solution Approach 2:
By storing the intercept and using it in conjunction with current slip ratio data, the system maintains continuous road surface state determination capability. This eliminates gaps in determination that would occur if calculation were restricted only to periods of sufficient driving force variation.
3Measurement precision
If a large number of data sets are collected for regression coefficient calculation, then the accuracy of road surface state determination is improved, but the response time and adaptability to changing conditions deteriorates
Solution Approach 1:
The system extracts and stores only the intercept parameter from the regression analysis, rather than recalculating the full regression coefficient continuously. This extraction reduces computational burden and allows faster response to changing conditions while maintaining determination accuracy through the use of stored intercept values.
Solution Approach 2:
Instead of collecting and processing a large number of data sets for full regression analysis at every determination point, the system uses a partial approach by utilizing the pre-stored intercept combined with current slip ratio data. This reduces the amount of data processing required while maintaining sufficient accuracy for road surface state determination.
Data Source
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AI summary
A determining apparatus for determining a state of a road surface is provided. The determining apparatus includes: a rotational velocity acquiring portion; a slip ratio calculating portion; a driving force acquiring portion; a slope calculating portion; and a determining portion. The slope calculating portion calculates the slope and an intercept, based on many data sets of the slip ratio and the driving force at the time of determination of a state of the road surface and therebefore, when a variation of the driving force is at least a certain value at the time of determination, and calculates the slope based on the data set of the slip ratio and the driving force at the time of determination of a state of the road surface, and the intercept that has been already obtained, when the variation is less than the certain value at the time of determination.