Wheel Load Estimation from Segmented Wheel-Speed Frequency Bands
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Solution Overview
Problem
Existing wheel load estimation methods, such as JP 2019-113373A, lack accuracy due to non-uniform changes in the frequency spectrum gain across the entire frequency band with changes in wheel load, leading to imprecise calculations.
Innovation Solution
A wheel load estimation device and method that includes a wheel speed acquisition unit, frequency characteristic ratio calculation unit, load ratio calculation unit, and wheel load calculation unit, which calculate front-to-rear and left-to-right load ratios by taking linear combinations of gain ratios at specific frequencies, using optimized weights to account for varying frequency band responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the gain integral of the entire frequency spectrum is used to estimate wheel load, then the estimation method is simple, but the accuracy is insufficient due to non-uniform changes across different frequency bands
Solution Approach 1:
The frequency spectrum is segmented into multiple frequency bands instead of treating it as a single integrated value. Each frequency band's gain is calculated separately, and the wheel load is estimated by combining these segmented frequency components. This segmentation allows the system to capture the non-uniform changes in different frequency bands, thereby improving estimation accuracy while maintaining computational simplicity.
2Ease of operation
If the gain changes in opposite directions across different frequency bands are not considered, then the calculation is straightforward, but the wheel load estimation accuracy deteriorates
Solution Approach 1:
The patent applies local quality by assigning different weights to different frequency bands based on their individual characteristics. Each frequency band's gain change is evaluated locally, and the weighting coefficients reflect the local sensitivity of each band to wheel load changes. This allows the system to account for opposite directional changes in different frequency bands, improving overall estimation accuracy while keeping the calculation process manageable through the use of pre-determined weights.
Data Source
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AI summary
A wheel load estimation device includes a wheel speed acquisition unit, a frequency characteristic ratio calculation unit, a load ratio calculation unit, and a wheel load calculation unit. The wheel speed acquisition unit acquires wheel speed information of each wheel included in the vehicle. The frequency characteristic ratio calculation unit calculates a front-to-rear frequency characteristic ratio and a left-to-right frequency characteristic ratio. The load ratio calculation unit calculates the front-to-rear load ratio and the left-to-right load ratio. The wheel load calculation unit calculates, a wheel load ratio representing a relative wheel load among the wheels included in the vehicle, for at least one of the wheels of the vehicle. The load ratio calculation unit calculates the front-to-rear load ratio by taking a linear combination of the calculated two or more front-to-rear gain ratios using weights that are different from one another.