Vehicle Stability Control via Selective Outer Wheel Braking
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Solution Overview
Problem
Existing vehicle safety systems struggle to effectively reduce the likelihood of over-steer during turns, particularly in front- and rear-engined vehicles, where rear wheels often lose traction before front wheels, leading to unstable vehicle rotation.
Innovation Solution
A method and computer program that adjust braking forces on individual wheels based on slip ratios and angles to maximize yaw moment, applying additional braking to the front outer wheel when its slip ratio is below a threshold and to both front and rear outer wheels when necessary to counteract over-steer, optimizing slip ratios between 50%-70% to maintain vehicle stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If braking forces are applied to the outer wheels during a turn to reduce over-steer, then vehicle stability is improved, but forward speed is excessively reduced
Solution Approach 1:
The braking system is segmented to apply different braking forces to different wheels based on their slip ratios. The processor independently controls braking at each wheel, allowing selective application of brake forces to front outer wheel or both front and rear outer wheels depending on detected over-steer conditions, thereby maintaining stability while minimizing overall speed loss
Solution Approach 2:
Instead of applying braking forces to all outer wheels uniformly, the system applies partial braking action only to the specific wheels that require it based on individual slip ratio measurements. This selective partial action provides just enough counter-steer moment to stabilize the vehicle without excessive braking that would unnecessarily reduce forward speed
2Ease of operation
If braking forces are applied to counteract over-steer, then vehicle control is improved, but traction is lost due to excessive braking
Solution Approach 1:
The system continuously monitors wheel slip ratios and uses this feedback to dynamically adjust braking forces. The processor detects over-steer conditions through slip ratio measurements and automatically modulates brake application to counteract the over-steer while preventing excessive braking that would cause traction loss. This closed-loop feedback control maintains optimal traction while improving vehicle control
Solution Approach 2:
The system changes the braking parameter (brake force magnitude) based on the detected slip ratio conditions. By dynamically adjusting the braking parameter according to real-time slip ratio measurements, the system optimizes the balance between providing sufficient counter-steer control and maintaining adequate traction at the wheels
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively reduces the likelihood of over-steer without excessive reduction in forward speed, enhancing safety and control during high-speed turns by maximizing yaw moment through targeted braking strategies.
Implementation Method 1
These forces arise from friction between the wheel and the road surface, and may be increased by braking forces applied to the wheel
Data Source
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AI summary
A method to reduce the likelihood of over-steer in a vehicle during a turn, the method, comprising the steps of: detecting that a vehicle is negotiating a turn in a manner that may result in an over-steer situation; determining inner and outer wheels of the vehicle, the inner wheels of the vehicle being those on the side towards which the vehicle is turning; determining the slip ratio of the forward outer wheel and the slip ratio of the rear outer wheel; and if the slip ratio of the rear outer wheel is below a first threshold, then: if the slip ratio of the front outer wheel is below a second threshold, applying additional braking to the front outer wheel only, without also applying additional braking at the rear outer wheel; or if the slip ratio of the forward outer wheel is above the second threshold, applying additional braking both to the front outer wheel and to the rear outer wheel.