Adaptive Steering Wheel Torque Detection for Uneven Roads
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Solution Overview
Problem
Current methods for detecting driver activity at the steering wheel of a moving vehicle are not precise enough, leading to false alarms and delayed detection of insufficient driver activity, particularly on uneven road surfaces.
Innovation Solution
Adaptive threshold values for the moment imparted by hand are set based on road surface conditions, including unevenness and friction coefficient, with dynamic time periods for successive measurements, allowing for continuous monitoring of both moment magnitude and gradient to accurately assess driver engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a constant threshold value is used for detecting driver activity, then the detection method is simple to implement, but the precision of detection deteriorates due to false alarms on uneven road surfaces
Solution Approach 1:
The threshold value is changed from a constant to a dynamic parameter that adapts to road surface conditions. The system continuously adjusts the threshold based on detected road unevenness, allowing the detection criterion to vary with environmental conditions rather than remaining fixed, thereby resolving the contradiction between simplicity and precision.
Solution Approach 2:
The threshold parameter is modified based on road surface characteristics. By changing the threshold value according to detected road conditions (smooth vs. uneven), the system achieves accurate driver activity detection across varying environments without requiring complex additional hardware.
2Reliability
If the threshold value is increased to account for road unevenness, then false alarms are reduced, but the detection becomes less sensitive to actual driver inactivity
Solution Approach 1:
Rather than using a single universally high threshold, the system dynamically adjusts the threshold parameter based on road conditions. On smooth roads, a lower threshold maintains sensitivity, while on uneven roads, a higher threshold reduces false alarms. This conditional parameter adjustment resolves the contradiction between reliability and sensitivity.
Solution Approach 2:
The threshold adapts dynamically to current road conditions rather than remaining statically high. This allows the system to be sensitive when needed (smooth roads) and reliable when needed (uneven roads), resolving the trade-off between false alarm reduction and inactivity detection sensitivity.
3Reliability
If the evaluation time period is extended to ensure accurate detection, then false alarms are reduced, but the response time to actual driver inactivity increases
Solution Approach 1:
The evaluation time period is made dynamic rather than fixed. The system adjusts the time window based on road conditions and driving context, allowing shorter evaluation periods when quick response is critical and longer periods when more data is needed for accurate assessment, thereby resolving the contradiction between reliability and response time.
Solution Approach 2:
The system performs repeated evaluations at different time intervals rather than using a single extended continuous evaluation. This periodic assessment allows the system to detect driver inactivity promptly while using multiple shorter evaluation windows to accumulate sufficient data for reliable determination.
Data Source
AI summary
A method detects a lack of driver activity at the steering wheel of a motor vehicle. A moment imparted by hand to the steering wheel by the driver is repeatedly measured, and if in a plurality of successive measurements the magnitude of a value of the moment imparted by hand does not exceed a threshold value, a lack of driver activity is inferred. The magnitude of the threshold value is dependent on the surface condition, in particular on the degree of unevenness, of the roadway being traveled upon. The degree of unevenness of the roadway may be derived from a measured vertical acceleration in the wheel suspension of the vehicle or from deceleration and/or acceleration signals of at least one wheel of the vehicle.