Steering Wheel Touch Detection Using Impedance and RC Sensing
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Solution Overview
Problem
Existing methods for detecting contact with a vehicle steering wheel, such as capacitive or resistive sensors, face challenges in accurately localizing the touch and are complex to implement, requiring additional components and increased assembly effort.
Innovation Solution
A device and method using a conductor arrangement with a conductor strand of significant ohmic resistance, applying alternating voltage, and determining the real and imaginary components of the impedance to evaluate the position of contact, allowing for precise touch detection and gesture recognition with minimal additional components and effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If capacitive or resistive sensors are integrated into the steering wheel to detect touch, then touch detection capability is achieved, but device complexity and installation effort increase significantly
Solution Approach 1:
The patent applies multi-functionality by using the existing conductor strands of the steering wheel (which serve dual purposes: structural/conductive function and sensor function) to perform both electrical conduction and touch detection. This eliminates the need for separate sensor components while achieving accurate touch detection capability.
Solution Approach 2:
The conductor strands of the steering wheel serve themselves by performing both their original electrical function and additional sensor function. The existing structure provides the sensing capability without requiring external sensor components, thereby reducing device complexity while maintaining measurement precision.
2Measurement precision
If additional wiring and components are added to locate the touch position on the steering wheel, then touch localization precision is improved, but installation effort and device complexity increase
Solution Approach 1:
The patent segments the steering wheel into multiple conductor strand zones, each with distinct electrical characteristics. By measuring the electrical properties of individual segments, the system can precisely locate touch position without requiring additional wiring throughout the entire steering wheel structure.
Solution Approach 2:
The patent replaces mechanical wiring and physical sensor components with electrical field-based detection using the existing conductor strands. This substitution achieves precise touch localization through electrical measurements rather than mechanical sensor arrays, significantly reducing installation effort while maintaining precision.
3Reliability
If conventional copper wire is used in the conductor arrangement, then electrical conductivity is improved, but the ability to form evaluable RC circuits for touch detection is reduced
Solution Approach 1:
The patent changes the electrical parameters of the conductor strands by selecting materials with specific resistance values that optimize both conductivity and RC circuit formation. The conductor strands have controlled resistance values that enable them to form evaluable RC circuits while maintaining sufficient electrical conductivity for reliable signal transmission.
Solution Approach 2:
The patent uses composite or specially formulated conductive materials that combine the properties of good electrical conductivity with appropriate resistance characteristics. These composite conductor strands achieve both reliable electrical connection and the necessary RC circuit behavior for touch detection, resolving the contradiction between conductivity and adaptability.
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 accurate detection of touch position and gesture recognition with reduced complexity and cost, providing reliable continuous monitoring and versatile evaluation for triggering functions.
Implementation Method 1
determining the capacitance or capacitance change of the conductor arrangement
Implementation Method 2
at least one conductor strand with a significant ohmic resistance
Implementation Method 3
determining the real and imaginary components of the AC resistance of the conductor arrangement
Data Source
Figure 1~4
AI summary
A method for detecting contact with a manually activated steering or control device, in particular a vehicle steering wheel, comprises the following steps: applying an alternating voltage to at least one conductor arrangement (10) which is arranged on the steering or control device, and has at least one conductor line with a significant ohmic resistance; determining the current profile in the conductor arrangement (10); determining the real component and the virtual component of the instantaneous alternating current resistance of the conductor arrangement (10); determining the capacitance or the change in capacitance of the conductor arrangement (10); determining the phase shift; and evaluating the determined values. A device for carrying out the method comprises a steering or control device, in particular a vehicle steering wheel, a conductor arrangement (10) which is arranged on the steering or control device and which has at least one conductor line with a significant ohmic resistance, and a control and evaluation device which is configured to apply an alternating voltage to the conductor arrangement (10), to measure the current profile in the conductor arrangement (10) and to evaluate the determined values.