Brake Fluid Pressure Control Using Estimated Vehicle Speed Deviation
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Solution Overview
Problem
Current techniques for determining bad road conditions lack precision, particularly in detecting subtle changes in wheel speed and vehicle body speed, leading to inaccurate ABS control and brake fluid pressure regulation.
Innovation Solution
A brake fluid pressure control device that calculates an estimated vehicle body speed and determines bad road conditions based on the deviation between wheel speed and vehicle body speed, using a threshold value adjusted according to the duration and slippage amount, enabling more accurate detection of road surface conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wheel speed fluctuation counting method is used to determine bad road conditions, then the determination can be made based on simple wheel speed data, but the precision of bad road determination is insufficient
Solution Approach 1:
The patent introduces an intermediary variable (estimated vehicle body speed) that mediates between the wheel speed sensor data and the bad road determination. By comparing wheel speed with this estimated vehicle body speed, the system achieves more precise bad road detection without requiring complex sensor arrays, thus resolving the contradiction between measurement precision and device complexity.
2Reliability
If ABS control parameters are adjusted based on bad road determination, then appropriate ABS control can be achieved, but the determination precision affects the control accuracy
Solution Approach 1:
The patent implements a feedback mechanism where the estimated vehicle body speed is continuously updated based on wheel speed data, and this updated estimate is fed back into the bad road determination process. This feedback loop enhances the reliability of ABS control by ensuring that the road surface state determination is based on the most current and accurate speed estimates, thereby improving both detection precision and control reliability.
3Measurement precision
If simple wheel speed threshold counting is used, then the system remains simple to implement, but it cannot detect subtle wheel speed deviations accurately
Solution Approach 1:
The patent changes the parameter used for bad road determination from simple wheel speed threshold counting to the deviation between wheel speed and estimated vehicle body speed. This parameter change enables the system to detect subtle wheel speed deviations accurately while maintaining implementation simplicity, as it still relies on basic arithmetic operations rather than complex algorithms.
Data Source
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AI summary
The invention relates to a brake fluid pressure control device for a vehicle capable of performing fluid pressure control of a brake fluid pressure applied to a wheel brake, the brake fluid pressure control device comprising: wheel speed acquisition means that acquires a wheel speed; estimated vehicle body speed calculation means that calculates an estimated vehicle body speed based on the wheel speed; and bad road determination means that determines whether a state of a traveling road surface is bad, wherein the bad road determination means determines whether the state of the traveling road surface is bad based on a deviation between the estimated vehicle body speed and the wheel speed.