Brake-by-Wire Force Redistribution for Comfort and Stability
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Solution Overview
Problem
Brake-by-wire systems in motor vehicles often result in uncomfortable compression of front shock absorbers due to unequal distribution of braking forces between front and rear wheels, leading to a suboptimal braking experience for occupants.
Innovation Solution
Implementing a brake-by-wire system with individually controllable braking actuators for each wheel, allowing for speed-dependent and dynamic redistribution of braking forces to optimize comfort by reducing front shock absorber compression during braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher braking forces are applied at front wheel brakes compared to rear wheel brakes, then vehicle deceleration is maximized and stability is improved, but front shock absorbers are excessively compressed leading to reduced occupant comfort
Solution Approach 1:
The patent applies dynamics by making the braking force distribution adjustable based on vehicle speed. At high speeds, front brakes provide higher forces for stability; at low speeds, the distribution shifts to reduce front shock absorber compression. This dynamic adaptation resolves the contradiction between maintaining stability and ensuring comfort across different operating conditions.
Solution Approach 2:
The patent changes the parameter of braking force distribution ratio between front and rear wheels based on vehicle speed threshold. When speed drops below the threshold, the system adjusts the braking forces to be more evenly distributed or shifted toward rear wheels, thereby reducing front shock absorber compression while maintaining adequate deceleration performance.
2Ease of operation
If braking forces are uniformly distributed between front and rear wheels, then shock absorber compression is reduced improving comfort, but vehicle deceleration performance and stability are compromised
Solution Approach 1:
The system dynamically adjusts braking force distribution based on real-time vehicle speed. During high-speed braking, it maintains front-heavy distribution for stability; during low-speed braking, it transitions to more uniform or rear-biased distribution for comfort. This conditional dynamics allows the system to optimize both stability and comfort according to operational context.
Solution Approach 2:
The patent implements parameter changes by adjusting the braking force distribution ratio as a function of vehicle speed threshold. This enables the system to switch between different braking strategies (front-heavy for stability vs. uniform for comfort) based on the current speed condition, thereby resolving the contradiction between deceleration performance and occupant comfort.
3Device complexity
If a central actuator controls all brakes, then system complexity is reduced, but individual wheel braking force adjustment capability is limited
Solution Approach 1:
The patent applies segmentation by dividing the braking control into individual wheel-level actuators rather than using a single central actuator. This allows independent control of braking forces at each wheel, enabling flexible distribution patterns (front-heavy, uniform, rear-biased) based on vehicle speed and braking conditions, thereby achieving high adaptability while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
The system uses dynamic control of individually controllable braking actuators to adjust braking force distribution in real-time based on vehicle speed threshold. This dynamic capability allows the system to adapt braking forces to different operational scenarios, providing versatility without requiring excessive mechanical complexity.
Data Source
AI summary
A method for controlling braking processes of a motor vehicle by a brake-by-wire braking system is described. Each front wheel and each rear wheel of a motor vehicle has an individually controllable braking actuator for achieving different braking forces. The braking actuators are controlled via the brake-by-wire braking system. The method begins with the following step: when the vehicle speed corresponds to that of a first specified threshold value or is greater than this threshold value, braking forces are set at the front wheel brakes and rear wheel brakes, wherein the set braking forces of the front wheel brakes are higher than those of the rear wheel brakes. In a second step, when the vehicle speed undershoots that of the first specified threshold value, the braking forces at the rear wheel brakes are increased in comparison with the braking forces thereof in the first step, and the braking forces at the front wheel brakes are reduced in comparison with the braking forces thereof in the first step.