Brake Force Distribution Control for Better Vehicle Braking Feel
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Solution Overview
Problem
Existing vehicle control methods do not effectively improve the braking feeling for a person on board across various deceleration ranges, as they do not consider the change in vehicle posture during braking, which affects the perception of deceleration and security.
Innovation Solution
A vehicle control method that adjusts the front-rear distribution ratio of braking force between the front and rear wheels based on the deceleration range, using a fixed distribution characteristic at low deceleration and biasing towards the rear wheels at higher deceleration, to enhance the perception of deceleration and security through pitch and heave changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed front-rear distribution ratio is used regardless of deceleration, then the braking force distribution is simple to control, but the feeling of braking is not improved across different deceleration ranges
Solution Approach 1:
The patent applies the dynamics principle by making the front-rear braking force distribution ratio variable according to deceleration magnitude. The brake control device dynamically adjusts the distribution ratio based on detected deceleration levels, switching between different distribution characteristics (e.g., front-biased at low deceleration, rear-biased at high deceleration) to optimize braking feeling across different operating conditions.
Solution Approach 2:
The patent implements parameter changes by modifying the front-rear braking force distribution ratio as a controllable parameter that varies with deceleration. The system changes this parameter based on the magnitude of deceleration, using different distribution ratios for different deceleration ranges to improve both low-speed and high-speed braking feelings.
2Device complexity
If a single braking force distribution characteristic is used, then the control system is simple, but the braking feeling cannot be optimized for both low and high deceleration ranges
Solution Approach 1:
The patent applies segmentation by dividing the deceleration range into multiple segments (low deceleration range and high deceleration range). Each segment has its own optimized distribution characteristic. The brake control device determines which segment the current deceleration falls into and applies the corresponding distribution characteristic, thereby optimizing braking feeling for each deceleration range while maintaining manageable system complexity.
Data Source
AI summary
A vehicle according to the present disclosure includes a brake device and an electronic control unit. The brake device is configured to change a front-rear distribution ratio of braking force with respect to front and rear wheels. The electronic control unit is configured to: control the brake device such that the front-rear distribution ratio is in accordance with a fixed distribution characteristic in which the front-rear distribution ratio is constant regardless of deceleration of the vehicle in at least a part of a first range being a required deceleration range lower than a lower limit value of the deceleration perceivable by a person in the vehicle; and control the brake device such that the front-rear distribution ratio is biased toward the rear wheel than that in the fixed distribution characteristic in a second range in which the deceleration is higher than that in the first range.