Dynamic Slip Threshold Adjustment for ABS Control
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Solution Overview
Problem
Existing vehicle movement dynamics control systems, such as ABS, struggle to differentiate between straight-ahead travel and curved path travel at low speeds, leading to premature activation during bends due to differences in wheel speeds, which can result in unnecessary intervention and reduced sensitivity.
Innovation Solution
A method to dynamically adjust the slip threshold based on wheel-specific slip signals, correlating and evaluating these signals to detect geometric slip, allowing for selective raising of the slip threshold only during curved path travel without requiring additional sensors like yaw rate or lateral acceleration sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the slip threshold is configured with a high value to avoid premature activation during curved path travel, then false ABS activation is reduced, but the sensitivity of ABS control is decreased
Solution Approach 1:
The slip threshold is made dynamic rather than static. The control device continuously monitors wheel speed differences between left and right wheels and automatically adjusts the slip threshold accordingly. During curved path travel, the threshold is raised to prevent false activation, while during straight-ahead travel, it returns to normal sensitivity levels. This dynamic adaptation resolves the contradiction by allowing the system to maintain high reliability when needed while preserving sensitivity during normal operation.
Solution Approach 2:
The slip threshold parameter is changed based on detected driving conditions. When a speed difference exceeding a predetermined threshold is detected between left and right wheels (indicating curved path travel), the slip threshold parameter is increased. When the speed difference falls within the normal range (indicating straight-ahead travel), the parameter returns to its original value. This parameter change strategy allows the system to adapt to different operational contexts, resolving the contradiction between reliability and sensitivity.
2Measurement precision
If the slip threshold is configured with a low value to maintain high sensitivity of ABS control, then detection accuracy is improved, but premature activation occurs during curved path travel
Solution Approach 1:
The system dynamically adjusts the slip threshold based on real-time wheel speed measurements. During straight-ahead travel, the threshold remains low to maintain high sensitivity and accurate detection. When curved path travel is detected through speed difference monitoring, the threshold automatically increases to prevent premature activation. This dynamic behavior resolves the contradiction by allowing low threshold values (high sensitivity) only when appropriate.
Solution Approach 2:
The slip threshold parameter is adaptively changed based on the detected maneuver type. The control device compares wheel speeds between left and right sides, and when the difference exceeds a predetermined value (indicating a curve), it raises the threshold parameter. When the difference is within normal limits (indicating straight travel), the parameter remains at its sensitive low value. This conditional parameter change resolves the contradiction between sensitivity and false activation.
3Measurement precision
If additional sensors like yaw rate or lateral acceleration sensors are added to differentiate straight-ahead and curved path travel, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The existing wheel speed sensors, originally designed for basic ABS functionality, are made multi-functional by utilizing them for both brake control and maneuver detection. The same sensors that monitor wheel speeds for anti-lock braking also detect speed differences between left and right wheels to identify curved path travel. This eliminates the need for additional yaw rate or lateral acceleration sensors, resolving the contradiction between detection accuracy and device complexity.
Solution Approach 2:
The ABS system serves itself by using its existing sensor infrastructure to detect curved path travel conditions. The wheel speed sensors already present in the ABS system provide sufficient information to distinguish between straight-ahead and curved travel through comparative analysis of left and right wheel speeds. This self-service approach avoids the need for additional dedicated sensors, resolving the contradiction between improved detection and increased complexity.
Data Source
AI summary
A method for setting a slip threshold for a vehicle movement dynamics control device of a motor vehicle is provided. The method includes defining a slip threshold starting from which the vehicle movement dynamics control device is activated in order to reduce slip, and determining wheel-specific minimum slip values for the wheels of the motor vehicle, which slip values are derived from the respective wheel-specific slip signals. The method also includes detecting a geometric slip by correlating all the determined wheel-specific minimum slip values with one another, and evaluating the wheel-specific minimum slip values that are correlated with one another. The method also includes raising the slip threshold in the event of geometric slip being detected. The present disclosure also relates to a vehicle movement dynamics control device.