Steering Wheel Capacitive Track Geometry for Grip Position Sensing
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Solution Overview
Problem
Current systems for detecting contact between a driver's hands and a steering wheel do not accurately determine the position or manner of gripping, which is crucial for driving safety.
Innovation Solution
A device with an electrically insulating support and conductive tracks that vary in height, width, or gap distribution to differentiate hand positions and gripping styles, using capacitance changes to determine contact and grip status, and optionally includes additional tracks for heating and shielding to prevent interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a simple contact sensor is used to detect hand contact with the steering wheel, then contact detection is achieved, but the position and gripping manner cannot be determined
Solution Approach 1:
The conductive track is segmented into multiple discrete peaks and troughs arranged in a specific pattern. Each peak represents a distinct contact zone, and by detecting which peaks are contacted, the system can determine the precise position and gripping manner of the driver's hand on the steering wheel, transforming a simple contact sensor into a position-sensitive sensor.
Solution Approach 2:
Different regions of the track have different geometrical characteristics (peak heights, trough depths, spacing variations) that create localized electrical properties. When a hand contacts different areas, it affects the capacitance or resistance in specific local regions, allowing the system to distinguish between different contact positions and gripping styles based on local electrical property changes.
2Measurement precision
If uniform conductive tracks are used across the steering wheel surface, then manufacturing is simplified, but the ability to differentiate hand positions is reduced
Solution Approach 1:
The track geometry parameters (peak height, trough depth, spacing between peaks) are systematically varied along the track length to create distinct electrical signatures for different contact zones. This parametric variation allows precise position differentiation while maintaining a relatively simple manufacturing process, as the variations follow predictable patterns that can be implemented through standard molding or printing techniques.
3Adaptability or versatility
If additional conductive tracks are added for heating and shielding functions, then functional versatility is improved, but interference between tracks increases
Solution Approach 1:
An electrically insulating support structure is introduced as an intermediary between the sensor track, heating track, and shielding track. This insulating layer electrically isolates the different conductive tracks, preventing harmful electromagnetic interference and capacitive coupling between them, while still allowing thermal energy from the heating track to pass through to the steering wheel surface and enabling the shielding track to function effectively.
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 determination of hand position and gripping manner on the steering wheel, ensuring correct grip detection and reducing false positives from external factors like water droplets.
Implementation Method 1
an electronic control unit to read and possibly process a variation of an electrical quantity induced by the contact of a user's hand with the steering wheel provided with the device according to the invention
Data Source
Figure 1A~1B
Figure 1C
Figure 1D~1E
AI summary
A device (100, 200', 200", 300, 400) for detecting the contact between a user and a steering wheel (9) of a vehicle, the device (100, 200', 200", 300, 400) comprising: - an electrically insulating support (10); - a first electrically conductive track (101, 201, 301, 401) fastened to the support (10) and comprising a plurality of first peaks (11) alternated with a plurality of first troughs (12) along a direction (D), wherein the first track (101, 201, 301, 401) is distributed over the support so that the surface of the first track (101, 201, 301, 401) adapted to come into contact with a user's hand decreases along said direction (D).