Vehicle Brake System Emergency Control on Low-Friction Roads
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Solution Overview
Problem
Existing vehicle brake systems fail to perform appropriate braking control when a vehicle encounters a collision on a low-friction road, as they do not account for the reduced traction conditions, leading to potentially longer braking distances and safety concerns.
Innovation Solution
A vehicle brake system that includes a brake pedal, a brake fluid pressure generator, a collision determination unit, and a braking control unit capable of performing emergency braking and ABS braking control based on wheel slip, regardless of the brake pedal's operation, to ensure appropriate braking on low-friction roads. The system continues emergency braking if the brake pedal is pressed down during a collision and switches to braking control based on the pedal's operation if ABS braking is not performed, and initiates ABS braking after a predetermined delay to stabilize wheel control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the vehicle brake system uses conventional braking control based on driver's brake pedal operation, then the system is simple to operate, but the braking distance becomes longer on low-friction roads during collision
Solution Approach 1:
The collision determination unit detects collision beforehand and triggers emergency braking control automatically before the driver can effectively respond. The system prepares and executes optimal braking action in advance based on detected collision conditions, eliminating the delay and imprecision of manual brake pedal operation during emergency situations on low-friction roads.
Solution Approach 2:
The braking control unit continuously monitors wheel slip conditions through sensors and adjusts brake fluid pressure in real-time based on feedback from the road surface conditions. This closed-loop control system automatically adapts to low-friction conditions by detecting wheel slip and modulating brake pressure, achieving optimal braking without requiring driver awareness or adjustment of brake pedal pressure.
2Reliability
If the system performs emergency braking control automatically during collision, then the braking distance is reduced, but the system complexity increases
Solution Approach 1:
The braking control unit integrates multiple functions into a single control system that can operate in different modes (emergency braking control and ABS braking control) based on detected conditions. The collision determination unit and wheel slip detection capability are combined within the existing brake fluid pressure generator framework, allowing the system to perform multiple braking functions without requiring entirely separate mechanical systems for each mode.
Solution Approach 2:
The system changes the operational parameters of the brake fluid pressure generator based on detected conditions. During collision, the system transitions from normal braking pressure parameters to emergency braking parameters with higher pressure and different modulation characteristics. The control unit adjusts pressure magnitude, rate of increase, and modulation frequency based on the emergency condition, achieving improved braking performance through parameter optimization rather than structural complexity.
3Reliability
If the system switches between emergency braking and ABS braking based on wheel slip, then the braking control is optimized, but the control logic becomes more complex
Solution Approach 1:
The braking control unit dynamically switches between emergency braking control and ABS braking control based on real-time wheel slip conditions. The system transitions from a static braking mode to a dynamic adaptive mode where the control strategy changes continuously based on detected wheel slip. This dynamic adjustment optimizes braking performance for varying road conditions without requiring complex manual intervention, as the control logic automatically adapts to the current state.
Data Source
AI summary
A vehicle brake system includes a collision determination unit that determines whether collision of the vehicle occurs or not; and a second braking control unit that, when the collision of the vehicle is determined as occurring, causes at least either of an ESB system and a VSA system to perform emergency braking control of the vehicle, and causes the VSA system to perform ABS braking control based on an ABS brake demand depending on a slip state of each wheel, irrespective of whether a brake pedal is pressed down or not. In a case where the vehicle collides, where the brake operation is performed, and where the ABS braking control is performed, the second braking control unit causes the emergency braking control based on an emergency brake demand to be continued instead of the braking control based on the press-down operation of the brake pedal by a driver.