Wheel Load Estimation via Frequency Analysis
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Solution Overview
Problem
Existing wheel load estimation methods require air pressure sensors and provide approximate wheel load values, necessitating a technique for improving estimation accuracy without relying on direct measurement or air pressure sensors.
Innovation Solution
A wheel load estimation device that acquires wheel speed information from sensors, calculates front-rear and left-right load ratios based on frequency characteristics of wheel accelerations, and computes wheel load ratios to estimate wheel loads with high accuracy using simple equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If air pressure sensors are installed in each tire to directly measure air pressure for wheel load estimation, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent uses wheel speed sensor data (which already exists in the vehicle) to create a proxy measurement system for wheel load. Instead of installing new air pressure sensors in each tire, the system copies the functionality by using existing sensor data combined with frequency analysis to estimate wheel load, thereby avoiding additional sensor installation complexity
Solution Approach 2:
The patent replaces the mechanical/direct measurement approach (air pressure sensors physically installed in tires) with a computational/electrical approach (using wheel speed sensor signals processed through frequency spectrum analysis). This substitution eliminates the need for physical sensor installation in tires while achieving wheel load estimation
2Measurement precision
If wheel load is measured directly with sensors, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The system creates a computational model that copies the wheel load measurement function using existing wheel speed sensor data. By analyzing the frequency characteristics of wheel speed signals, the system reproduces wheel load information without requiring direct physical measurement sensors on the wheels
Solution Approach 2:
The patent makes the existing wheel speed sensor system serve dual purposes: both speed measurement and wheel load estimation. The wheel speed sensor data is processed through frequency spectrum analysis to extract wheel load information, allowing the existing sensor to provide multiple functions without additional hardware
3Device complexity
If approximate wheel load values are used without direct measurement, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent utilizes the vibration characteristics inherent in wheel speed signals at different frequencies. By analyzing the frequency spectrum of wheel speed data, the system extracts information about wheel load based on how load affects the vibrational characteristics of wheel rotation, transforming simple speed data into precise load estimates
Solution Approach 2:
The system transforms the wheel speed parameter into wheel load information by changing the analysis domain from time-domain speed measurement to frequency-domain spectrum analysis. This parameter transformation allows accurate wheel load estimation to be derived from simple wheel speed sensor data through mathematical processing
Data Source
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AI summary
Provided is a wheel load estimation device configured to acquire wheel speed information of each wheel included in a vehicle from a wheel speed sensor provided in the vehicle; to calculate a front-rear load ratio and a left-right load ratio based on the wheel speed information; and to calculate a wheel load ratio expressing a relative wheel load between the wheels included in the vehicle, with respect to at least one wheel of the vehicle, based on the front-rear load ratio and the left-right load ratio. The front-rear load ratio is a ratio between a load applied to a front wheel of the vehicle and a load applied to a rear wheel of the vehicle, and the left-right load ratio is a ratio between a load applied to a left wheel of the vehicle and a load applied to a right wheel of the vehicle.