Anti-lock Brake Control Device Slip Estimation Delay Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing anti-lock brake control systems face challenges in swiftly and accurately determining wheel slipping tendencies, leading to potential delays in starting anti-lock brake operations, especially due to estimation errors and noise, which can increase braking distance and result in erroneous detections.
Innovation Solution
The anti-lock brake control device employs a slip estimator with delay compensators to perform delay compensation on wheel motion estimation results, allowing for comparison of multiple compensated estimation results to accurately determine slipping tendencies, thereby reducing noise and enabling swift and accurate slip state determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a low-pass filter is used to remove noise from wheel motion signals, then measurement precision is improved, but response time deteriorates due to detection delay
Solution Approach 1:
The system performs preliminary classification of wheel motion signals into normal braking regions and slip occurrence regions based on predetermined thresholds. By pre-identifying the operational region, the system can then apply appropriate filtering strategies - aggressive filtering in normal regions and minimal filtering in slip regions - thereby removing noise without causing detection delays in critical slip conditions.
Solution Approach 2:
The filtering strategy is dynamically adjusted based on the current operational state. In normal braking regions, a low-pass filter with stronger noise removal capability is applied. When slip is detected or suspected, the filtering is reduced or bypassed to ensure rapid detection. This dynamic adaptation resolves the contradiction between noise removal and response time.
2Measurement precision
If the threshold value for slip detection is set low to improve detection sensitivity, then measurement precision is improved, but reliability deteriorates due to erroneous detection from noise
Solution Approach 1:
The system preliminarily classifies the current state as either normal braking or slip occurrence based on predetermined thresholds before making the final slip detection determination. This preliminary classification acts as a gatekeeper that prevents erroneous detections by ensuring that low threshold comparisons only occur when the system is already in a confirmed slip region, thereby maintaining both sensitivity and reliability.
Solution Approach 2:
The preliminary slip region determination acts as an intermediary layer between the raw signal and the final slip detection decision. This intermediary step filters out false positives by requiring that the system first be in a validated slip region before accepting low-threshold slip detections, thus resolving the contradiction between sensitivity and reliability.
3Reliability
If conservative threshold settings are used to prevent erroneous detection, then reliability is improved, but productivity deteriorates due to delayed anti-lock brake operation
Solution Approach 1:
The system performs preliminary determination of slip occurrence regions using conservative thresholds to ensure reliability. Once the system is confirmed to be in a slip region through this preliminary step, subsequent slip detections can proceed with higher sensitivity without risking erroneous operations. This two-stage approach maintains reliability while enabling faster response when slip is confirmed.
Solution Approach 2:
The detection strategy dynamically transitions from conservative threshold monitoring in normal regions to more sensitive detection in confirmed slip regions. This dynamic adjustment allows the system to maintain high reliability during normal operation while achieving fast response times when anti-lock braking is actually needed, thus resolving the contradiction between reliability and productivity.
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The anti-lock brake control device includes: a wheel motion estimator (13) to estimate one or more of an angle, an angular velocity, and an angular acceleration of a wheel (2); a slip estimator (14) to estimate a slip state of the wheel, using an estimation result of the wheel motion estimator (13); and an anti-lock controller (15) to give a command for causing a brake device (1) to reduce a braking force, in accordance with the estimated slip state of the wheel. The slip estimator (14) includes delay compensators (17a, 17b), such as one or a plurality of filters, which perform delay compensation for the estimation result of the wheel motion estimator (13). The anti-lock controller (15) gives the command for reducing the braking force, on the basis of a result of predetermined determination including comparison of the plurality of estimation results outputted from the slip estimator (14).