Vehicle Brake Split Road Detection via Wheel Deceleration Differences
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Solution Overview
Problem
Existing vehicle brake hydraulic pressure control systems may erroneously determine that a split road condition exists due to differences in tire wear or frictional forces between wheels, leading to potential deterioration in braking performance by restricting brake fluid pressure differences.
Innovation Solution
A vehicle brake hydraulic pressure control apparatus that includes a hydraulic pressure adjusting unit, a wheel deceleration calculating section, and a split road determining section, which individually adjusts brake fluid pressures and determines if road surfaces constitute a split road based on predetermined values of wheel decelerations and their differences, preventing erroneous determinations of split road conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If brake fluid pressure difference is restricted based on maximum wheel deceleration alone, then split road control is activated, but braking performance deteriorates due to erroneous determination
Solution Approach 1:
The patent applies local quality by examining wheel deceleration differences specifically between right and left wheels rather than using a single maximum value threshold for all wheels. This localized comparison approach allows the system to distinguish between split road conditions (where opposite wheels show significant deceleration differences) and normal conditions (where all wheels show similar deceleration patterns), thereby improving determination accuracy without compromising braking performance
Solution Approach 2:
The patent segments the wheel deceleration analysis into separate comparisons for right and left wheels. Instead of treating all four wheels uniformly with a single maximum threshold, the system divides the analysis to compare deceleration values between corresponding wheels on opposite sides of the vehicle. This segmentation enables more precise detection of split road conditions while avoiding erroneous activations that would degrade braking performance
2Device complexity
If maximum wheel deceleration threshold is used for split road detection, then detection simplicity is maintained, but measurement precision decreases due to tire wear variations
Solution Approach 1:
The patent improves measurement precision by applying local quality to the detection algorithm - instead of using a single maximum deceleration threshold for all wheels, it compares deceleration values between specific wheel pairs (right vs left). This localized comparison method maintains relatively simple algorithmic structure while significantly improving detection accuracy by accounting for tire wear variations and frictional force differences between individual wheels
Solution Approach 2:
The patent inverts the conventional approach by not simply detecting the maximum deceleration value, but rather by examining the difference or relationship between deceleration values of opposite wheels. This inversion transforms the detection logic from an absolute threshold method to a relative comparison method, thereby improving precision without substantially increasing algorithmic complexity
Data Source
AI summary
A wheel deceleration calculating sections individually calculate, as negative values, wheel decelerations of front and rear wheels. If, at a time when the antilock braking control for at least one of the right and left front wheels is started or at a time when the antilock braking control for at least one of the right and left rear wheels is started, (i) a maximum value of the wheel decelerations calculated by the wheel deceleration calculating sections is equal to or larger than a first predetermined value and (ii) a difference between the wheel decelerations of the right and left front wheels or the right and left rear wheels which are in an antilock braking control state is equal to or larger than a second predetermined value, a split road determining section determines that road surfaces constitute a split road.