Adaptive Wheel Speed Calibration Using Longitudinal Acceleration
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Solution Overview
Problem
Conventional vehicle stability systems face inaccuracies in calculating vehicle speed due to deviations in tire sizes, particularly from wear or changes in tire diameters, leading to erroneous wheel speed calculations and potential rollover prevention issues.
Innovation Solution
A method that integrates longitudinal acceleration sensor signals with wheel rpm sensor signals to identify and adaptively recalibrate tire circumferences, ensuring deviations fall within a predefined tolerance range, eliminating the need for manufacturer parameterization and enabling automatic calibration during driving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional rpm correction (tire compensation) is applied to individual tires with wheel speeds deviating from calculated vehicle speed, then tire speed matching is improved, but vehicle speed calculation accuracy deteriorates when all tire sizes deviate equally from the original parameterized value
Solution Approach 1:
The system continuously compares wheel speeds from all four sensors with the calculated vehicle speed and uses this feedback to iteratively adjust the tire circumference parameters. The electronic control unit monitors the differences between individual wheel speeds and the mean vehicle speed, and automatically recalibrates the tire circumference values to minimize these deviations, ensuring both tire speed matching and accurate vehicle speed calculation are maintained simultaneously
Solution Approach 2:
The system performs automatic self-calibration without requiring manual intervention or manufacturer parameterization. The electronic control unit uses the wheel speed sensors and vehicle speed calculations to automatically detect tire size deviations and adjust the tire circumference parameters itself, enabling the system to adapt to tire wear and size changes autonomously
2Measurement precision
If tire size parameterization is fixed during vehicle manufacture, then initial vehicle speed calculation is accurate, but the system cannot adapt to tire wear or tire size changes over time
Solution Approach 1:
The system transitions from static, manufacturer-fixed tire size parameters to dynamic, automatically adjusting parameters. The electronic control unit continuously monitors wheel speeds and recalibrates the tire circumference values in real-time based on actual operating conditions, allowing the system to adapt to tire wear and size changes while maintaining accurate vehicle speed calculation
Solution Approach 2:
The system automatically changes the tire circumference parameters based on detected deviations in wheel speeds. When the electronic control unit identifies that wheel speeds deviate from the calculated vehicle speed beyond a threshold, it adjusts the tire circumference parameters to compensate for tire wear or size changes, thereby maintaining measurement accuracy without manual intervention
3Device complexity
If lateral acceleration is calculated from wheel rpm differences, then the system avoids additional sensors, but calculation errors are amplified when raised to the power of two
Solution Approach 1:
The system uses feedback from wheel speed comparisons to continuously correct tire circumference parameters, which in turn reduces errors in lateral acceleration calculations. By maintaining accurate tire size parameters through continuous calibration, the system minimizes the propagation of errors when calculating lateral acceleration from wheel rpm differences
Solution Approach 2:
The system performs preliminary calibration of tire circumference parameters using wheel speed data before calculating lateral acceleration. This preliminary adjustment ensures that the base values used for lateral acceleration calculation are as accurate as possible, reducing the impact of error amplification when these values are processed
Data Source
AI summary
A method and apparatus for calibrating wheel speed signals measured by wheel rpm sensors in a vehicle equipped with at least one longitudinal acceleration sensor integrates the signal of the longitudinal acceleration sensor during the acceleration or deceleration phases of the vehicle, and the resulting vehicle speed signal is compared against the signals of the individual wheel rpm sensors. A determination is made as to whether a deviation that may exist for a wheel lies within a predefined tolerance range. If a deviation falls outside of the tolerance range, the parameterized tire circumference of the associated wheel is adaptively recalibrated until the deviation falls within the tolerance range.