Vehicle Center of Gravity Height Estimation Using Braking Dynamics
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Solution Overview
Problem
Existing methods for determining the height of a vehicle's center of gravity require specialized sensors not typically found in modern trucks, making them costly and impractical for vehicles with traditional mechanical suspensions.
Innovation Solution
A method that estimates the vehicle's center of gravity height using available sensors and information, such as wheel rotation speed, vehicle acceleration, wheel slippage rate, braking forces, and road slope, during two distinct braking periods with different decelerations, without the need for additional sensors or equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If specialized sensors (pressure sensors in air cushions) are used to determine vertical load on each wheel, then the accuracy of center of gravity height determination is improved, but the system cost increases and the method becomes inapplicable to vehicles with traditional mechanical suspensions
Solution Approach 1:
The method utilizes data already being collected by the vehicle's existing sensors (wheel rotation speed, braking forces, engine torque) for other purposes such as anti-lock braking and stability control. By repurposing this existing data for center of gravity determination, the system avoids additional sensor costs while maintaining measurement accuracy.
Solution Approach 2:
The existing sensor system is made multi-functional by using the same sensors for both their original purposes (braking control, stability programs) and for determining center of gravity height. This eliminates the need for specialized sensors while enabling the new measurement capability.
2Reliability
If multiple specialized sensors are installed to measure vertical load on each wheel, then the reliability of center of gravity determination is improved, but the ease of operation and applicability to different vehicle types deteriorates
Solution Approach 1:
The method is designed to work with the standard sensor suite found in modern trucks regardless of suspension type. By using universally available sensors (wheel speed sensors, braking force sensors) rather than suspension-specific sensors, the method maintains reliability across air suspension, mechanical suspension, and hybrid suspension configurations.
Solution Approach 2:
The vehicle's existing sensor system serves multiple functions including both safety systems and center of gravity determination. This self-service approach ensures the method works reliably across different vehicle types without requiring vehicle-specific sensor installations.
3Measurement precision
If advanced sensing equipment is used to determine center of gravity position, then the measurement precision is improved, but the device complexity and computational requirements increase
Solution Approach 1:
The method uses data already being processed by the vehicle's existing control systems for braking and stability functions. By leveraging this existing computational infrastructure and data stream, the method achieves accurate center of gravity determination without adding complex sensing or computing hardware.
Solution Approach 2:
The existing vehicle computer system performs multiple functions by processing sensor data for both safety systems and center of gravity determination. This multi-functional approach maintains measurement precision while avoiding additional computational hardware requirements.
Data Source
AI summary
A method is provided for estimating the height of the gravity center of a vehicle having at least a front axle and a rear axle each carrying at least two wheels. The method includes determining a first braking period and a second braking period occurring along road portions having substantially the same slope, but where the first and second braking periods result in different vehicle decelerations, and during both braking periods, estimating at least the following variables: vehicle acceleration; the wheel slippage rate for the front and rear axles; the braking forces or braking torque at each of the front and rear axles, or a ratio thereof; and the slope of the corresponding road portion. The method also includes estimating, using only the foregoing estimations made during both periods, the vehicle center of gravity height.