Wheel Diameter Variation Detection Using Reference Wheel Speed
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Solution Overview
Problem
Conventional methods for detecting wheel diameter variations between vehicle wheels fail to accurately represent relative variations, leading to improper detection and calculation of wheel speeds and vehicle behavior control.
Innovation Solution
A wheel diameter variation-detecting device using wheel rotational speed sensors and a microcomputer-based ECU to calculate a variation parameter, such as the tire diameter ratio, between wheels, with learning mechanisms to account for temporary disturbances and ensure reliable calculations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the average value of all wheel speeds is used to calculate diameter correction, then a correction value can be obtained, but the method cannot properly detect relative variation in diameter between wheels
Solution Approach 1:
The patent extracts and compares individual wheel speed differences relative to a reference wheel, rather than using a global average. This isolates the relative diameter variation information from each wheel pair, preserving the specific relative variation data that would be lost in a comprehensive average calculation.
Solution Approach 2:
The patent segments the wheel speed data by comparing each wheel individually against a reference wheel, creating separate variation parameters for different wheel pairs. This segmentation preserves the relative variation information between specific wheels, which would be averaged out and lost in a single global average calculation.
2Ease of manufacture
If wheel speeds are calculated based on a predetermined diameter, then calculation is simple, but accuracy deteriorates when actual diameter changes due to aging or variation
Solution Approach 1:
The patent dynamically changes the diameter parameter from a fixed predetermined value to a corrected value derived from actual wheel speed measurements. By calculating correction values based on relative wheel speed variations and applying these to adjust the predetermined diameter, the system adapts to actual diameter changes due to aging or manufacturing variations, improving accuracy while maintaining the simplicity of using a base diameter value.
3Reliability
If conventional diameter correction methods are used, then some compensation is achieved, but relative variation between individual wheels cannot be properly detected
Solution Approach 1:
Instead of calculating a global average and deriving corrections from that, the patent inverts the approach by using each wheel's speed relative to a reference wheel to directly determine individual diameter variations. This inversion allows direct detection of relative diameter differences between wheels, providing both reliable wheel speed calculations and precise relative variation detection simultaneously.
Data Source
AI summary
The present disclosure presents a wheel diameter variation-detecting device capable of properly detecting relative variation in diameter between a plurality of wheels of a vehicle. The wheel diameter variation-detecting device can detect variation in diameter between a plurality of wheels of a vehicle, can detect rotational speeds of the respective wheels, and can calculate a variation parameter indicative of variation in diameter between the wheels using one of the wheels as a reference wheel, based on a result of comparison between the rotational speed of the reference wheel and that of one of the wheels other than the reference wheel. Further, the wheel diameter variation-detecting device can learn the variation parameter based on a value obtained by averaging a plurality of values of the variation parameter obtained before the detected travelled distance reaches a predetermined distance.