Vehicle Brake Control Device Bad Road Determination
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Solution Overview
Problem
Existing vehicle brake control systems face challenges in accurately determining bad road conditions and correcting slip ratios for anti-lock brake control, leading to suboptimal performance.
Innovation Solution
A vehicle brake control device that calculates two types of wheel accelerations with different responsiveness, using these to determine bad road conditions and adjust slip corrections accordingly, improving the accuracy of anti-lock brake control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single wheel acceleration value is used for bad road determination, then the determination process is simple, but the accuracy of bad road determination is insufficient
Solution Approach 1:
The wheel acceleration is segmented into two distinct components: a first wheel acceleration (raw, unfiltered) and a second wheel acceleration (filtered, with high-frequency components removed). This segmentation allows the system to compare different characteristics of the same physical quantity to improve detection accuracy.
Solution Approach 2:
The system dynamically adjusts the bad road determination criteria based on the relationship between the two acceleration values. By using a boundary line that increases with the second wheel acceleration, the system adapts to varying driving conditions while maintaining accurate bad road detection.
2Measurement precision
If wheel speed is corrected on the increasing side for bad road conditions, then the slip ratio calculation is simplified, but the accuracy of anti-lock brake control deteriorates
Solution Approach 1:
The system changes the correction parameter (bad road amount) dynamically based on the first wheel acceleration value. When a bad road is detected, the slip amount is corrected by adding a bad road amount that is proportional to the first wheel acceleration, allowing precise adaptation to different road conditions.
Solution Approach 2:
The system uses feedback from the first wheel acceleration to continuously adjust the bad road amount. This feedback mechanism ensures that the correction applied to the slip amount is always appropriate for the current road condition, improving control accuracy.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
A vehicle brake control device including a wheel speed acquisition section, a wheel acceleration calculation section, an anti-lock brake control section, a bad road determination section, and a bad road amount setting section. The wheel acceleration calculation section calculates a first wheel acceleration and a second wheel acceleration. The bad road determination section determines that a running road surface is a bad road when the calculated first wheel acceleration is larger than a first boundary line where the first wheel acceleration increases as the second wheel acceleration is larger in an area where the first wheel acceleration is larger than the second wheel acceleration. The bad road amount setting section increases a bad road amount as the calculated first wheel acceleration is larger when it is determined that a running road surface is a bad road.