Adaptive Traction Control Wheel Speed Ratio
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Solution Overview
Problem
Traction control systems falsely activate when vehicle components such as tire size or differential are modified, leading to unnecessary interventions.
Innovation Solution
The system adjusts to changes in rolling radius and differential ratios by determining reference speeds, driven wheel speeds, and applying filtering schemes to adapt the wheel speed ratios, preventing false activations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the traction control system uses a fixed reference speed assumption based on standard tire size, then the system operates correctly under standard conditions, but the system falsely activates when tire size or differential is modified
Solution Approach 1:
The system dynamically adjusts the reference speed calculation by introducing an adaptive ratio parameter that evolves over time. Instead of using a fixed reference speed based on standard tire size, the system continuously updates the expected driven wheel speed ratio compared to non-driven wheels, allowing it to adapt to modified tire sizes and differential configurations while maintaining reliable operation under standard conditions
Solution Approach 2:
The system changes the parameter used for reference speed determination from a fixed value to a dynamically adjusted value. By modifying the reference speed ratio parameter based on observed wheel speed differences, the system can accommodate various tire sizes and differential modifications without false activations, while preserving correct operation with standard components
2Adaptability or versatility
If the system rapidly adapts to component changes, then false activations are reduced, but the system may become sensitive to normal variations in wheel speed
Solution Approach 1:
The system uses periodic evaluation of wheel speed ratios over time intervals to determine adaptation needs. By continuously monitoring the ratio between driven and non-driven wheel speeds and updating the reference ratio periodically, the system adapts to component changes at an appropriate rate while filtering out normal transient variations that could trigger false activations
Solution Approach 2:
The system implements feedback mechanisms that monitor wheel speed ratios and adjust the reference speed calculation accordingly. The feedback loop compares actual driven wheel speeds against the adaptive reference, allowing the system to distinguish between genuine component modifications requiring adaptation and normal operational variations, thus balancing adaptability with reliability
Data Source
AI summary
A method of controlling a traction control system (30) includes continuously adapting a steady state driven wheel speed to reference wheel speed ratio, so that said traction control system can avoid unnecessary actuations (e.g., demanding torque reduction). The continuous adaptation methodology provides traction control robustness to vehicles equipped with a spare tire, or a different final drive such as in the use of aftermarket parts. The method includes a dual rate adaptation that allows both fast adaptation and fine tuning capabilities of the ratio. The method includes comparing the instant driven wheel speed to reference wheel speed ratio to the filtered driven wheel speed to reference wheel speed ratio, to obtain a ratio difference. When the difference is above a threshold, the first filter constant is selected and the first constant is applied to an adaptation filter, resulting in a first filtered and adapted ratio. The traction control system is controlled with the adapted ratio. When the difference is below the threshold, the second filter constant is selected and the selected constant is applied to the adaptation filter, resulting in the second filtered and adapted ratio. The traction control system is controlled with the adapted ratio.