Vehicle Slip Control Signal Processing for Braking Vibration
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Solution Overview
Problem
False excitations of a slip control system in vehicle brake systems occur due to vibrations in wheel speed signals, which can be misinterpreted as slip, leading to unnecessary slip control activation and inhomogeneous deceleration profiles.
Innovation Solution
Monitoring the wheel speed signal for specific criteria such as the start of a negative half-wave and re-acceleration during predetermined periods to differentiate between braking-induced vibrations and actual slip, adjusting control thresholds accordingly to avoid false slip detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensitive slip control thresholds are used to detect small slips, then slip control sensitivity is improved, but false excitations occur due to wheel vibrations being misinterpreted as slip
Solution Approach 1:
The monitoring of wheel speed signals is segmented into different phases: a first monitoring period immediately following brake application to detect braking-induced vibrations, and subsequent periods for normal slip detection. This temporal segmentation allows the system to apply different detection criteria appropriate to each phase, resolving the contradiction between sensitivity and false excitation.
Solution Approach 2:
The system performs preliminary detection of braking-induced vibrations during the first monitoring period before normal slip control activation. By identifying and flagging vibration patterns early, the system prevents false slip control excitations while maintaining sensitive detection capabilities for actual slip conditions.
2Stability of the object's composition
If slip control is activated sensitively for small slips, then deceleration homogeneity is improved, but unnecessary slip control activation occurs due to wheel vibrations
Solution Approach 1:
The control activation process is segmented into phases: during the first monitoring period, the system specifically monitors for vibration patterns characteristic of braking-induced oscillations and suppresses slip control activation for these patterns. In subsequent periods, sensitive slip control is activated for actual slip conditions, ensuring deceleration homogeneity without unnecessary activation.
Solution Approach 2:
The system converts the harmful effect of wheel vibrations (which cause false slip detection) into a beneficial discrimination mechanism. By learning to recognize the specific pattern of braking-induced vibrations, the system can distinguish these from actual slip conditions, transforming what was previously a source of false excitations into a reliable indicator for suppressing unnecessary control activation.
Data Source
AI summary
A method for avoiding false excitations of a slip control system comprises monitoring of a wheel speed signal for a predefined first monitoring time period for the start of a negative half-wave of an oscillation applied to a vehicle wheel, when a brake pressure gradient initiated by a brake start rises above a predetermined threshold. A ruck signal is derived from the wheel speed signal. An acceration signal is derived from the wheel speed signal during a predetermined second monitoring period. The wheel speed signal is monitored for a turning point of the ruck signal and a start of the acceleration signal. The oscillation imposed on the vehicle wheel is identified as a braking-induced vibration, and slip control is not carried out when the turning point of the ruck signal and the re-acceleration of the wheel are detected.