Tire Load Estimation via Radial Acceleration Waveform Analysis
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Solution Overview
Problem
Existing methods for estimating tire load require multiple sensors on the inner surface of each tire tread and have insufficient accuracy, even when considering air pressure.
Innovation Solution
A method and device that detect acceleration waveforms in the tire radial direction using acceleration sensors, calculate ground contact time and rotation time, and estimate tire load using a ground contact time ratio, total vehicle weight, and a linearly approximated maximum load capability ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple piezoelectric elements are disposed on the inner surface side of each tire tread to detect load changes in circumferential and width directions, then ground contact area can be calculated, but the device complexity and sensor quantity increase
Solution Approach 1:
The invention extracts only the necessary measurement information (radial acceleration) from the tire system, eliminating the need for multiple piezoelectric elements. By focusing on a single sensor type and orientation, it achieves load estimation without requiring complex multi-directional sensor arrays, thus reducing device complexity while maintaining measurement capability
Solution Approach 2:
The invention replaces the mechanical piezoelectric element-based load detection system with an acceleration sensor-based system. This substitution uses dynamic acceleration measurements during tire rotation to infer static load conditions, thereby reducing the number of sensors needed while achieving comparable or improved measurement precision
2Measurement precision
If load is estimated using ground contact area and air pressure, then air pressure is taken into consideration, but the load estimation accuracy remains insufficient
Solution Approach 1:
The invention changes the measurement parameter from static ground contact area to dynamic acceleration waveform characteristics. By measuring radial acceleration during tire rotation and analyzing the waveform (particularly the zero-crossing points), it derives load information more accurately. This parameter change enables precise load estimation without requiring complex combinations of multiple parameters like air pressure and ground contact area
Solution Approach 2:
The invention uses the acceleration waveform feedback during tire rotation to continuously monitor and determine load conditions. The zero-crossing points of the acceleration waveform provide real-time feedback about the tire's contact with the ground, enabling accurate load estimation through a straightforward relationship between waveform characteristics and load, without needing complex calculations involving air pressure
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for precise tire load estimation with fewer sensors and improved accuracy without the need for pre-created maps of load vs. ground contact time ratios.
Implementation Method 1
an acceleration sensor disposed on an inner surface side of a tire tread of the tire... detecting an acceleration waveform in a tire radial direction
Data Source
Figure 1~2(b)
Figure 3(a)~3(b)
Figure 4
AI summary
A tire load estimation device includes: acceleration sensors 11 each disposed on each tire; a total vehicle weight calculating means 12; an acceleration waveform extracting means 13 that detects, for each tire, an acceleration waveform in a tire radial direction from an output signal of each of the acceleration sensors 11; a differential acceleration waveform calculating means 14 that obtains a differential acceleration waveform of the acceleration waveform; a peak position detecting means 15 that detects a peak position on a leading edge side and a peak position on a trailing edge side in the differential acceleration waveform; a ground contact time ratio calculating means 16 that calculates a ground contact time and a rotation time from the peak positions to calculate a ground contact time ratio which is a ratio between the ground contact time and the rotation time; and a lord estimating means 17 that estimates the load acting on the tire from the ground contact time ratio of each tire, a maximum load capability of the tire, the total vehicle weight, and an inclination obtained in advance by approximating a maximum load capability ratio, which is a value obtained by normalizing the load with the maximum load capability, with a linear function of the ground contact time ratio.