Wheel Radius Correction Using Yaw Rate Feedback in Cornering
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Solution Overview
Problem
Existing methods for determining wheel radius in vehicles are inadequate as they require driving straight for a period and are not suitable for dynamic conditions, such as cornering, leading to inaccuracies due to changing wheel circumference caused by factors like air pressure, temperature, and wear.
Innovation Solution
A method that calculates a yaw rate using wheel speed and a predetermined wheel radius, compares it with a measured yaw rate, and adjusts the wheel speed with a correction factor to determine a corrected wheel radius and speed, allowing for accurate radius determination in dynamic conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wheel radius is determined using predetermined values and standard calculation methods, then the determination process is simple, but the accuracy deteriorates due to changing wheel circumference caused by air pressure, temperature, and wear
Solution Approach 1:
The patent applies feedback by measuring the actual yaw rate and comparing it with the calculated yaw rate to generate a correction factor. This correction factor is then fed back to adjust the wheel radius determination, creating a closed-loop system that continuously improves accuracy based on actual vehicle behavior
Solution Approach 2:
The patent changes the parameter used for wheel radius determination from fixed predetermined values to dynamic values adjusted by a correction factor. This correction factor is derived from the ratio of measured to calculated yaw rates, allowing the system to adapt to changing wheel circumference conditions
2Adaptability or versatility
If existing methods require driving straight for a period to determine wheel circumference, then measurement stability is improved, but the adaptability to dynamic conditions deteriorates
Solution Approach 1:
The patent transitions from static measurement methods (requiring straight-line driving) to a dynamic method that uses yaw rate measurements during actual vehicle operation. The correction factor is calculated based on real-time yaw rate data, enabling accurate wheel radius determination under varying driving conditions
Solution Approach 2:
The patent performs preliminary calculation of the yaw rate using predetermined wheel radius values before comparing with measured values. This preliminary calculation provides a baseline that enables the subsequent correction process to work effectively
Data Source
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AI summary
The invention relates to a method for determining a wheel radius of a motor vehicle, which comprises the following steps: *calculating a yaw rate of the motor vehicle, formula (I), by means of a wheel speed (V FL ,V FR , V RL , V RR ) of at least one wheel (FL,FR,RL,RR) and a specified wheel radius (r), *comparing the calculated yaw rate, formula (I), with a measured yaw rate, formula (II), *adapting the wheel speed (V FL ,V FR , V RL , V RR ), which has been input into the calculation of the yaw rate, of the at least one wheel (FL,FR,RL,RR) by means of a correction factor (K RR, K FR , K RL , K RR ), so that the calculated yaw rate, formula (I), is equal to the measured yaw rate, formula (II), *multiplying the correction factor (K RR, K FR , K RL , K RR ) and the specified wheel radius (r) or the wheel speed (V FL ,V FR , V RL , V RR ) which has been input into the calculation of the yaw rate, in order to determine a corrected wheel radius or a corrected wheel speed (VFL,corr, VFR,cor, VRL,corr, VRR,corr ).