Driving Support Device Steering Torque Thresholds
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Solution Overview
Problem
Existing driving support devices may incorrectly determine that a driver has not fallen into an incompetent state due to increased steering torque from lane keeping control, leading to inappropriate failure to initiate deceleration control when the driver has indeed fallen into an incompetent state.
Innovation Solution
A driving support device that determines the driver's incompetent state by monitoring both steering torque and touch finger number on the steering handle, using different torque and number thresholds to differentiate between holding and non-holding states, thereby reducing incorrect determinations and ensuring appropriate deceleration control is initiated when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If lane keeping control generates steering torque to keep the vehicle on target path, then steering accuracy is improved, but false detection of driver holding state occurs leading to incorrect determination of driver incompetence
Solution Approach 1:
The patent divides the steering torque threshold into multiple levels: a first threshold for normal lane keeping control and a second, higher threshold for determining driver incompetence. This segmentation allows the system to distinguish between torque generated by normal lane keeping operations and torque indicating active driver intervention, thereby resolving the false detection problem while maintaining measurement precision.
2Measurement precision
If steering torque threshold is set low to detect driver holding state, then detection sensitivity is improved, but false positive increases due to lane keeping control torque
Solution Approach 1:
The patent implements dynamic threshold adjustment where the steering torque threshold for detecting driver holding state changes based on the operational mode. During normal lane keeping control, a first threshold is used, but when determining driver incompetence, a second higher threshold is applied. This dynamic adaptation allows sensitive detection during normal operation while preventing false positives during incompetence determination.
3Reliability
If incompetent state determination time period is extended to ensure accuracy, then determination reliability is improved, but response time to actual incompetence increases
Solution Approach 1:
The patent performs preliminary assessment of driver holding state using the first steering torque threshold during normal lane keeping control. When the driver releases the steering wheel, the system immediately switches to the second higher threshold for incompetence determination. This preliminary action allows the system to be prepared and respond quickly when actual incompetence occurs, reducing the determination time period while maintaining reliability.
Data Source
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AI summary
The driving support ECU 10 performs a steering control for changing a steering angle in such a manner that an own vehicle travels along a target path. When a state in which holding state information does not satisfy a first condition continues for a first time threshold or more, the ECU starts a first alert and continues the steering control. The holding state information includes information indicative of a steering torque and represents a holding state of a steering handle by a driver. When a state in which the holding state information does not satisfy a second condition for a second time threshold or more after the first alert is started, the ECU starts a deceleration control. The second condition is a condition satisfied when the holding state information indicates that the driver holds the steering handle more firmly than when the holding state information satisfies the first condition.