Vehicle Active Device Control Using Predictive Lateral Acceleration
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Solution Overview
Problem
Existing vehicle control systems experience delays in activating active devices during high cornering forces, leading to suboptimal deployment of occupant restraints and aerodynamic devices, which affects occupant comfort and vehicle performance due to the inherent lag in responding to lateral acceleration peaks.
Innovation Solution
A method that generates a steering signal from the steering angle and its rate of change to advance the activation of active devices, such as seat belts and aerodynamic devices, by predicting the severity of cornering events based on vehicle speed and steering inputs, allowing earlier and more timely deployment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a threshold-based control system is used for active devices, then the device deployment is simple and reliable, but there is an inevitable delay in vehicle response as the measured parameter increases toward the threshold
Solution Approach 1:
The system performs preliminary action by deploying the active device before the lateral acceleration actually reaches the threshold value. It calculates a predicted peak lateral acceleration based on current acceleration and steering input rate, then triggers deployment when this predicted value exceeds the threshold. This anticipatory deployment eliminates the inherent delay in threshold-based systems while maintaining reliable operation.
2Loss of time
If the threshold is set low for early deployment, then response time is improved, but the active device will be repeatedly deployed causing occupant irritation
Solution Approach 1:
The system uses feedback by continuously monitoring the actual lateral acceleration and comparing it with the predicted peak value. Deployment is triggered only when the predicted acceleration exceeds the threshold, and the system tracks whether actual acceleration subsequently exceeds the threshold to prevent repeated unnecessary deployments. This feedback mechanism ensures deployment occurs at the optimal moment without causing occupant irritation from false activations.
3Ease of operation
If the threshold is set high to avoid repeated deployment, then occupant comfort is improved, but greater movement of the occupant occurs before deployment with higher contact load
Solution Approach 1:
The system performs preliminary action by predicting the peak lateral acceleration using the current acceleration rate and steering input rate. It triggers deployment when this predicted value exceeds the threshold, which occurs earlier than waiting for actual threshold crossing but later than immediate low-threshold triggering. This timing optimization reduces both occupant movement distance and contact load while preventing repeated deployments.
4Reliability
If aerodynamic devices are deployed later, then false deployment is reduced, but the effectiveness of the device action on the vehicle is reduced
Solution Approach 1:
The system uses feedback by continuously comparing predicted peak lateral acceleration with the deployment threshold. It triggers aerodynamic device deployment when the predicted value exceeds the threshold, ensuring deployment occurs at the optimal moment for maximum effectiveness. The system monitors actual acceleration to confirm the cornering event is genuine, preventing false deployment while maintaining high device effectiveness through timely activation.
Data Source
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AI summary
A method of triggering an active device of a vehicle at a pre-determined threshold comprises generating a steering wheel signal from steering angle rate of change of steering angle of the vehicle, the signal representing an advance in time in comparison to the steering wheel position and/or speed, and determining a conditioned vehicle lateral acceleration in dependence on the steering wheel signal and a measured vehicle lateral acceleration, the conditioned vehicle lateral acceleration being advanced in time in comparison with the measured vehicle lateral acceleration. An active device of the vehicle is triggered if the conditioned vehicle lateral acceleration exceeds a threshold lateral acceleration.