Brake Pressure Control for Reduced Stopping Distance
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Solution Overview
Problem
Existing hydraulic braking systems face challenges in reducing braking distance, especially on low friction surfaces, as conventional ABS systems require significant modulation and work to prevent wheel lockup, which can increase braking distance on slippery surfaces.
Innovation Solution
A method and system that utilize a brake master cylinder coupled with an electronic control unit and ABS, which monitors and reduces brake pressure to a level below the driver's requested pressure but above the wheel lock pressure, maintaining the vehicle in ABS mode to minimize wheel slip and reduce braking distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ABS prevents wheel lock during braking, then wheel lockup is avoided, but braking distance increases on low friction surfaces
Solution Approach 1:
The system dynamically adjusts the brake pressure threshold based on road friction conditions. On low friction surfaces, it lowers the activation threshold to prevent ABS engagement until higher pressure is applied, allowing the wheels to maintain better contact and reduce braking distance while still preventing lockup
Solution Approach 2:
The brake pressure modulation becomes more aggressive and responsive on low friction surfaces, with the system continuously adapting pressure levels based on real-time wheel speed feedback and estimated friction conditions to optimize stopping performance
2Reliability
If ABS is activated when brake pressure exceeds 100% adhesion utilization, then wheel lockup is prevented, but brake pressure cannot be optimized for low friction surfaces
Solution Approach 1:
The system uses wheel speed sensors and slip ratio calculations to continuously monitor braking conditions and provide feedback to the control algorithm, which then adjusts brake pressure in real-time to maintain optimal slip ratios adapted to current road friction conditions
Solution Approach 2:
The system pre-calculates and stores friction coefficient estimates from initial braking phases, using this information to proactively adjust activation thresholds and pressure modulation strategies before wheel lockup conditions develop
Data Source
AI summary
A method for reducing the braking distance for a vehicle having an anti-lock braking mechanism (ABS) and a hydraulic braking system detects a brake pressure requested by the vehicle's driver (Prequested), and calculates the brakes pressure values at which the wheels of the vehicle lock. A maximum brake pressure value of these different brake pressure values is then compared with the driver's requested brake pressure value (Prequested). If the requested brake pressure value is much higher than the maximum brake pressure value, then the actual brake pressure applied at different wheels (Pactual) is set to a level below the requested brake pressure (Prequested), but still higher than the maximum brake pressure value. This reduces the amount of work required to be done by the ABS in pumping the excessive brake fluid out of the braking system of the vehicle, and allows for precise control of ABS mechanism during wheel slip conditions.