Vehicle Gravity Center Estimation Using Wheel Force Sensing
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Solution Overview
Problem
Existing gravity center estimation devices for vehicles are unable to accurately estimate the gravity center position due to discrepancies between commanded torque and actual torque applied to the wheels.
Innovation Solution
An estimation device that acquires braking-driving force information from in-wheel sensors, calculates wheel loads, and estimates the gravity center position based on these values, ensuring accurate measurement of actual forces applied to the wheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If commanded torque values are used to estimate wheel load, then the estimation process is simple, but the accuracy of gravity center position estimation deteriorates due to discrepancies between commanded and actual torque
Solution Approach 1:
The patent replaces the computational estimation method (using commanded torque values and vehicle dynamics models) with direct physical measurement using in-wheel force sensors. These sensors measure actual braking and driving forces applied to each wheel, providing accurate force data that directly reflects the true wheel loads without relying on torque command assumptions or complex dynamic models.
Solution Approach 2:
The in-wheel force sensors act as intermediaries between the wheel-hub assembly and the gravity center estimation system. Instead of calculating wheel loads from commanded torque through multiple computational steps, the sensors directly measure the actual forces transmitted to the wheels, serving as a reliable intermediary that provides accurate input data for gravity center position calculation.
2Measurement precision
If in-wheel force sensors are used to measure actual braking-driving force, then the accuracy of wheel load measurement is improved, but the device complexity and cost increase
Solution Approach 1:
The patent divides the force measurement function into four separate in-wheel force sensors, with each sensor installed in an individual wheel hub assembly. This segmentation allows each sensor to independently measure the braking or driving force for its specific wheel, providing localized accurate measurements that collectively enable precise gravity center position estimation without requiring a complex centralized measurement system.
Solution Approach 2:
The in-wheel force sensors serve multiple functions: they measure both braking forces and driving forces, provide data for gravity center position estimation, and can potentially support other vehicle control functions. This multi-functionality justifies the added device complexity by providing a versatile measurement solution that addresses multiple vehicle dynamics requirements simultaneously.
Data Source
AI summary
An estimation device is provided with a braking-driving force acquiring unit that acquires, based on a signal from a sensor that detects a force, braking-driving force information as information indicating a braking force or a driving force applied to wheels of the vehicle; a wheel load acquiring unit that acquires, based on the braking-driving force information, a wheel load received by the wheels from a road surface; and an estimation unit that estimates, based on a value of the wheel load of each wheel included in the vehicle, a gravity center position of the vehicle.