Dynamic Wheel Circumference Estimation for Vehicle Speed Accuracy
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Solution Overview
Problem
Existing methods for estimating a vehicle's wheel circumference are inadequate as they do not sufficiently account for dynamic changes such as tire expansion and variations in tire size, leading to excessive deviations in speed calculations.
Innovation Solution
A method and device that estimate a current wheel circumference by determining a reference speed and wheel rotational speed, storing these values in a circular buffer, and calculating a current wheel circumference based on stored values, allowing for dynamic adjustments and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a static wheel circumference value with margin of safety is used, then reliability of speed indication is improved, but measurement precision deteriorates due to excessive deviations
Solution Approach 1:
The patent applies dynamics by transitioning from a static wheel circumference value to a dynamic estimation approach. The system continuously estimates the current wheel circumference based on actual wheel rotational speeds and reference speeds, allowing the value to adapt to changing conditions such as tire expansion at different speeds and variations in actual tire sizes, thereby resolving the contradiction between reliability and measurement precision.
Solution Approach 2:
The patent implements feedback by using the determined current wheel circumference to calculate vehicle speed and comparing it with reference speed measurements. This feedback loop allows the system to continuously refine and update the wheel circumference estimation, improving measurement precision while maintaining reliability through self-correction.
2Reliability
If a mean value of wheel circumferences with safety margin is used, then reliability is improved, but adaptability deteriorates due to inability to account for actual tire size variations
Solution Approach 1:
The patent applies self-service by enabling the system to automatically determine and adapt to the actual wheel circumference of the specific tires mounted on the vehicle. Instead of relying on predefined mean values, the system uses actual wheel rotational speed measurements and reference speeds to self-determine the current wheel circumference, thereby achieving both reliability and adaptability.
Solution Approach 2:
The patent implements parameter changes by allowing the wheel circumference parameter to vary dynamically based on actual operating conditions. The system estimates the current wheel circumference as a specific value that reflects the actual tire size and conditions, rather than using a fixed mean value, enabling the system to adapt to different tire sizes and maintain reliable speed determination.
3Reliability
If wheel circumference is increased to account for tire expansion at speed, then reliability is improved, but measurement precision worsens due to excessive deviations from actual circumference
Solution Approach 1:
The patent applies dynamics by making the wheel circumference value speed-dependent through continuous estimation. The system determines the current wheel circumference based on actual wheel rotational speeds and reference speeds, allowing the value to automatically adjust for tire expansion effects at different speeds without using a fixed increased margin, thereby maintaining both reliability and precision.
Data Source
AI summary
The invention relates to a method for estimating a current wheel circumference of at least one wheel arranged on a vehicle, said method comprising: determining a reference speed of the vehicle at a point in time by means of a reference apparatus, detecting a wheel rotational speed of the at least one wheel at said point in time by means of a wheel rotational speed sensor, estimating a single wheel-circumference value based on the determined reference speed and the detected wheel rotational speed for said point in time by means of a calculation apparatus, storing at least the estimated single wheel-circumference value in a circular buffer for said point in time, estimating a current wheel circumference based on the single wheel-circumference values stored in the circular buffer by the calculation apparatus, outputting the estimated current wheel circumference as a wheel circumference signal.