Intermeshing Capacitive Sensor Structures for Steering Wheel Hand Position Detection
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Solution Overview
Problem
Existing sensor systems for motor vehicle steering wheels cannot accurately determine the position of a human hand, only providing sector-based detection rather than spatial resolution for hands-on-off detection.
Innovation Solution
The sensor system employs intermeshing capacitive sensor structures arranged over the steering wheel surface, utilizing a combination of CVD self and mutual methods to detect changes in capacitive coupling with the environment and/or a reference electrode, and incorporates active shielding and heating structures to enhance detection precision and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sector-wise arranged sensor devices are used for hands-on/off detection, then the approach and departure of a human hand can be detected area by area, but precise determination of hand position is not possible
Solution Approach 1:
The sensor device is divided into multiple sensor structures arranged in a comb-like pattern, where each sensor structure independently detects capacitive changes in its specific detection area. This segmentation allows precise localization of hand position by identifying which specific sensor structures detect the hand, rather than using a single large sensor area.
Solution Approach 2:
The sensor structures are arranged in a comb-like pattern extending in the circumferential direction of the steering wheel, adding a spatial dimension to the detection. This arrangement creates overlapping detection areas that enable precise hand position determination through ratio calculation of capacitive changes across multiple sensor structures.
2Measurement precision
If multiple sensor structures are arranged to improve hand position detection, then location resolution within a defined area is achieved, but the device complexity increases
Solution Approach 1:
Multiple sensor structures are merged into a single integrated sensor device with a comb-like arrangement. The sensor structures share common evaluation electronics and control mechanisms, allowing them to function as a unified system rather than independent sensors, thereby reducing overall device complexity while maintaining high location resolution.
Solution Approach 2:
The sensor device performs multiple functions: detecting hand presence, determining hand position, and providing location resolution within defined areas, all through the same comb-like sensor structure arrangement. This multi-functionality eliminates the need for separate detection systems for each function.
3Reliability
If capacitive sensor structures are used for hand detection, then hands-on/off detection is achieved, but detection accuracy and reliability need improvement
Solution Approach 1:
The sensor device continuously monitors capacitive coupling changes and uses this feedback to dynamically adjust detection parameters. The evaluation device calculates ratios of capacitive changes from multiple sensor structures, providing feedback that improves the accuracy and reliability of hand position detection by compensating for environmental variations.
Solution Approach 2:
The sensor device detects changes in capacitive coupling parameters caused by hand presence. By monitoring parameter changes (capacitive coupling variations) across multiple sensor structures and calculating their ratios, the system achieves more accurate and reliable detection compared to single-parameter detection methods.
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
Enables precise spatial resolution of hand position and angle of grip on the steering wheel, improving detection accuracy and reliability for hands-on-off operations by distinguishing the presence and movement of a human hand through capacitive changes.
Implementation Method 1
the presence of a human hand in a detection area of a sensor structure causes a detectable change, assigned to the respective sensor structure, in a capacitive coupling of the sensor structure with the environment and/or a reference electrode
Data Source
Figure 1a~1b
Figure 2
AI summary
The invention relates to a sensor system for a motor vehicle steering wheel (10), comprising a capacitive sensor device and a control device for controlling the sensor device, said capacitive sensor device comprising at least two electrically conductive sensor structures (11) and is designed to detect the presence of a human hand in the gripping area of the steering wheel. The presence of a human hand in a detection area of the sensor structure respectively provokes a modification of a capacitive coupling of the sensor unit with the surroundings and/or a reference electrode with respect to a reference state, said modification being associated with the sensor structure and can be detected. The two sensor structures (11) are arranged so that they at least partially mesh and are designed for arranging in the gripping area of the steering wheel. A position of a human hand, which is located in the detection area of the sensor structure (11), can be determined from the ratio of the modifications of the capacitive coupling with the surroundings and/or a reference electrode, said modifications being associated with the individual sensor structures (11) and can be detected. The invention also relates to a steering wheel (10) comprising said type of sensor system and to a method for operating said type of sensor system.