Steering Wheel Grip Sensor Voltage Threshold Adjustment
Solution Overview
Problem
Automated driving systems often mistakenly determine that a vehicle occupant is gripping the steering wheel when they are not, due to contact with other body parts during automated driving, leading to incorrect gripping requests.
Innovation Solution
A vehicle control device with a grip sensor and a grip determination unit that adjusts the determination level of sensors on the steering wheel, making it easier to determine non-gripping in certain areas and harder in others, preventing false positives by changing voltage thresholds based on driving states and learned positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the grip sensor is provided along the entire circumference of the steering wheel to detect gripping state, then the measurement precision of gripping state is improved, but wrong determination occurs when vehicle occupant contacts the steering wheel with body parts other than hands during automated driving
Solution Approach 1:
The patent applies local quality by setting different determination levels for different areas of the grip sensor. The lower part of the steering wheel (where body parts may contact during automated driving) has a different determination level compared to other areas. This allows the system to maintain high sensitivity in areas where hand gripping occurs while reducing false positives in areas where body contact during automated driving is more likely.
2Productivity
If the determination level of the grip sensor is lowered to detect gripping more sensitively, then the productivity of gripping detection is improved, but false positive determination occurs when vehicle occupant does not grip the steering wheel
Solution Approach 1:
The patent implements local quality by dividing the steering wheel into different areas with different determination levels. The lower part has a higher threshold to prevent false positives during automated driving, while other areas maintain lower thresholds for sensitive gripping detection. This resolves the contradiction by allowing high productivity in appropriate areas without sacrificing reliability.
3Reliability
If the grip sensor is avoided in particular parts of the steering wheel to prevent wrong determination, then the reliability of gripping determination is improved, but it becomes difficult to perform accurate gripping determination when vehicle occupant grips those parts
Solution Approach 1:
The patent applies parameter changes by modifying the determination level (threshold) of the grip sensor based on the driving state and sensor position. Instead of removing sensors from certain areas, the system dynamically adjusts the determination parameters - using higher thresholds in the lower part of the steering wheel during automated driving to prevent false positives while maintaining sensor coverage for complete gripping position detection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Reduces incorrect determinations that the vehicle occupant is gripping the steering wheel, ensuring accurate gripping requests and transitions between automated and manual driving modes.
Implementation Method 1
Japanese Laid-Open Patent Publication No. 2015-147531 discloses a steering system that is provided with an electrostatic capacitance sensor as the grip sensor
Data Source
AI summary
If a vehicle controller makes a gripping request, a grip determination unit changes a determination level (voltage threshold) of a grip sensor that is positioned in a particular area of a disposed area where a steering wheel is disposed, in a manner that it becomes less easy to determine that the steering wheel is gripped and it becomes easier to determine that the steering wheel is not gripped, compared with a determination level (voltage threshold) of the grip sensor that is positioned in an area other than an area in a particular direction.