Vehicle Loading State Estimation Using Stability Factor
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Solution Overview
Problem
Conventional methods for estimating a vehicle's loading state struggle to accurately determine the loading state when the steering angular velocity is small or during steady turns, as the phase difference between steering angle and yaw rate becomes negligible, limiting their effectiveness in these conditions.
Innovation Solution
A method and device that utilize a relationship between predetermined loading states, stability factors, and lateral acceleration, where the stability factor is calculated based on vehicle traveling data and used in conjunction with stored reference relationships to estimate the loading state, even when the vehicle is in a steady turn or has a small steering angular velocity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase difference between steering angle and yaw rate is used for loading state estimation, then loading state can be estimated based on steering response characteristics, but loading state cannot be estimated accurately when steering angular velocity is small or during steady turns
Solution Approach 1:
The patent changes the estimation parameter from phase difference (which becomes negligible at low steering angular velocities) to stability factor (which remains effective across all steering conditions). The stability factor is calculated from the relationship between lateral acceleration and yaw rate, providing a reliable indicator of loading state even during steady turns or when steering angular velocity is small.
2Reliability
If conventional phase difference method is used, then loading state estimation is feasible under normal steering conditions, but the method fails when the vehicle is in steady turn condition or has small steering angular velocity
Solution Approach 1:
The patent introduces stability factor as an intermediary parameter that mediates between lateral acceleration and yaw rate to estimate loading state. This intermediary approach allows the system to bypass the limitation of phase difference method and provides reliable estimation across diverse driving conditions including steady turns and low steering angular velocity scenarios.
Data Source
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AI summary
A predetermined relationship among various loading states, stability factor (Kh) of a vehicle and lateral acceleration (Gy) of the vehicle is stored in a storage device (30A) as a reference relationship (i.e. a map). Information regarding a lateral acceleration (Gy) of the vehicle is acquired using a lateral acceleration sensor (40). An estimated value of the stability factor (Kh) of the vehicle is calculated on the basis of vehicle travelling data when turning. A loading state of the vehicle is estimated on the basis of the area in which the estimated value of the stability factor and the lateral acceleration of the vehicle which is at the same point in time as the vehicle travelling data which were provided for the calculation of the estimated value belong in the reference relationship.