Steering Wheel Capacitive Sensor Layout for Fault-Tolerant Hand Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In vehicles with safety-relevant functions, such as automated driving, there is a need for a reliable and accurate method to detect the presence and input of a driver's hands on the steering wheel to ensure safe operation and functionality of the operating device.
Innovation Solution
A sensor device with multiple electrically conductive sensor electrodes and an evaluation unit connected via multiple connection lines allows for precise capacitance measurements, including continuity tests and resistance measurements, to detect the presence of an input device and identify potential errors in the sensor electrodes, enhancing detection accuracy and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single sensor electrode is used for capacitive detection, then the device structure remains simple, but detection reliability and accuracy are insufficient for safety-relevant functions
Solution Approach 1:
The patent divides a single sensor electrode into multiple segments (first sensor electrode and second sensor electrode) that can be independently evaluated. Each segment has its own connection lines leading to the evaluation unit, allowing separate continuity testing and capacitance measurement. This segmentation enables reliable detection of local defects while maintaining overall system functionality, directly addressing the need for enhanced detection reliability in safety-relevant applications.
Solution Approach 2:
The patent implements preliminary continuity tests and resistance measurements between different connection lines of the sensor electrode segments before actual capacitive detection. By pre-evaluating the electrical integrity of each segment through the evaluation unit, the system can identify potential faults early and ensure that only functional segments are used for safety-critical detection, thereby enhancing overall system reliability.
2Measurement precision
If multiple connection lines are added to sensor electrodes for continuity testing, then error detection capability improves, but device complexity increases
Solution Approach 1:
The patent designs the evaluation unit to perform multiple functions using the same connection lines: continuity testing, resistance measurement, and capacitance detection. The connection lines serve dual purposes - both as signal paths for capacitive sensing and as test paths for error detection. This multi-functionality approach enables precise error detection without proportionally increasing device complexity, as the same hardware infrastructure supports multiple evaluation modes.
Solution Approach 2:
The sensor electrode system performs self-diagnosis through built-in continuity tests and resistance measurements conducted by the evaluation unit. The system uses its own connection lines and power supply to automatically detect faults in its components without requiring external testing equipment. This self-service capability enables continuous monitoring of electrode integrity and automatic identification of defective segments.
3Reliability
If redundant sensor elements are used for multiple detection, then detection reliability improves, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple sensor electrode segments (first and second sensor electrodes) into a single integrated sensor surface structure. Rather than manufacturing separate redundant sensors and assembling them, the segments are formed as interconnected parts of one unified component. This merging approach maintains the reliability benefits of redundant detection while simplifying manufacturing, as the segments share common fabrication processes and can be evaluated through a single evaluation unit.
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
The sensor device provides enhanced accuracy in detecting the presence of an input device and identifying sensor electrode faults, ensuring reliable operation of safety-relevant functions by using multiple capacitance measurements and error detection methods, thereby improving the safety and reliability of vehicle control systems.
Implementation Method 1
the evaluation unit is configured to measure the capacitance with respect to a system ground at a terminal of the first sensor electrode
Implementation Method 2
When an input device approaches the capacitive sensor electrode or makes contact with it, the electric field between the sensor electrode and the reference potential or ground is altered
Data Source
Figure 1~2
Figure 3a~3b
Figure 3c~4
AI summary
The invention relates to a sensor device for a vehicle for the capacitive recognition of input means in the area of a detection surface, comprising a first and a second sensor electrode, and an evaluation unit, which is electrically connected via connection lines to a respective first connection of the first and the second sensor electrode. The aim of the invention is to provide a particularly accurate and reliable sensor device for a vehicle for the capacitive recognition of input means. The aim of the invention is achieved by using second connections on the first and second sensor electrodes, respectively, and by corresponding methods for recognizing the presence of input means, and for error recognition.