Vehicle Slip Suppression Control Using Multi-Threshold Wheel Speed Monitoring
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Solution Overview
Problem
Conventional traction control systems struggle to quickly restore drive wheel traction on a road surface, particularly when the slip is significant, leading to prolonged reduction in driving power and potential loss of drivability.
Innovation Solution
A slip suppression control system that uses a monitored value detecting device to compare the rotational speed difference between the front and rear wheels, with multiple thresholds to adjust driving power reduction based on the magnitude of the slip, including ignition timing, throttle valve opening, and fuel injection, allowing for dynamic control of driving power according to engine speed and vehicle state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single threshold is used for traction control, then the control system is simple, but the driving power reduction continues for a long time when slip is significant
Solution Approach 1:
The single threshold is segmented into multiple thresholds (first threshold and second threshold) with different values. The first threshold is lower and activates traction control earlier, while the second threshold is higher and triggers a larger driving power reduction. This segmentation allows the system to respond differently based on the severity of slip, restoring traction faster without excessive complexity.
Solution Approach 2:
The system changes the control parameter (driving power reduction amount) based on the monitored value relative to different thresholds. When the monitored value exceeds the first threshold, a first driving power reduction is applied. When it exceeds the second threshold, a second (larger) driving power reduction is applied. This parameter change enables adaptive response to varying slip conditions.
2Loss of time
If driving power is reduced significantly to suppress slip quickly, then traction is restored faster, but drivability deteriorates due to excessive power reduction
Solution Approach 1:
Different control actions are applied based on the local condition of slip severity. For moderate slip (above first threshold but below second threshold), a moderate driving power reduction is applied. For severe slip (above second threshold), a larger driving power reduction is applied. This local quality approach ensures that drivability is maintained when slip is not severe, while still enabling fast traction restoration when slip is significant.
Solution Approach 2:
The control system dynamically adjusts the driving power reduction amount based on real-time monitoring of wheel speed difference. The system transitions between different control states (first driving power reduction and second driving power reduction) as the monitored value crosses different thresholds, enabling adaptive response that balances slip suppression speed with drivability.
3Reliability
If traction control is activated for any slip condition, then slip is suppressed, but unnecessary control activation occurs reducing drivability
Solution Approach 1:
The system uses multiple thresholds to create different control activation conditions. The first threshold activates traction control for moderate slip conditions, while the second threshold activates stronger control for severe slip conditions. This parameter-based activation ensures that control is only applied when necessary, avoiding unnecessary intervention in normal driving conditions while maintaining reliable slip suppression when needed.
Data Source
AI summary
A slip suppression control system for a vehicle comprises a monitored value detecting device for detecting a monitored value corresponding to a difference between a rotational speed of a front wheel of the vehicle and a rotational speed of a rear wheel of the vehicle; a threshold determiner unit configured to determine a relationship between the monitored value detected by the monitored value detecting device and plural thresholds; and a controller configured to execute traction control for reducing a driving power of a drive wheel based on determination of the threshold determiner unit; wherein the plural thresholds have at least first and second thresholds, and the second threshold is set larger than the first threshold; and wherein the traction control includes an amount-change-based control.