Vehicle Roll Rate Estimation for Active Device Triggering
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Solution Overview
Problem
Existing vehicle active device deployment systems face delays due to relying solely on lateral acceleration, which peaks as the vehicle exits a corner, leading to suboptimal occupant comfort and potential irritation from repeated deployments or excessive movement before activation.
Innovation Solution
A method that uses lateral acceleration, steering angle, and rate of change of steering angle to estimate vehicle roll rate, allowing for timely deployment of active devices such as seat belt tensioners or seat bolsters, with thresholds adjusted for corner category and speed to optimize deployment timing and comfort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the active device is triggered based on lateral acceleration threshold, then the device deployment is simple and reliable, but the deployment occurs too late (after occupant movement has already commenced) reducing comfort and increasing contact load
Solution Approach 1:
The system performs preliminary calculation of estimated vehicle roll rate using steering angle and its rate of change before the lateral acceleration threshold is reached. This allows the active device to be triggered in advance of actual high lateral acceleration, compensating for deployment delay and improving occupant comfort without requiring complex real-time measurements.
Solution Approach 2:
The patent introduces an intermediate calculated parameter (estimated vehicle roll rate) that mediates between the easily measurable steering angle and the desired deployment timing. This intermediary variable provides an early indication of cornering severity, enabling timely device activation without directly measuring complex vehicle dynamics.
2Ease of operation
If a low threshold is set for active device deployment, then occupant comfort is improved by early deployment, but the device will be repeatedly deployed causing irritation
Solution Approach 1:
The system changes the triggering parameter from raw lateral acceleration to estimated vehicle roll rate calculated from steering angle dynamics. This parameter transformation allows for more accurate discrimination between significant cornering events requiring deployment and minor variations that would cause false activations, improving both comfort and reliability.
3Reliability
If a high threshold is set for active device deployment, then false deployments are reduced, but greater occupant movement occurs before deployment increasing contact load
Solution Approach 1:
By calculating estimated vehicle roll rate from steering angle and its rate of change, the system achieves preliminary detection of significant cornering events before lateral acceleration peaks. This enables deployment at an optimal threshold level that is high enough to avoid false activations but low enough to activate before substantial occupant movement occurs, reducing contact load.
Data Source
Figure 1~3
AI summary
An active device of a vehicle, for example a seat belt tensioner, is triggered by reference to an estimated vehicle roll rate exceeding a threshold roll rate. The estimated vehicle roll rate may be conditioned according to vehicle speed, and is determined from inputs of vehicle lateral acceleration, steering wheel angle, and steering wheel speed.