Multi-Area Capacitive Presence Detection for Motor Vehicle Door Handles
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Solution Overview
Problem
Existing door handle detection systems in motor vehicles are prone to false hand presence detection due to external elements like moisture and are complex and costly to implement for multi-area detection.
Innovation Solution
A detection device with two capacitors per detection area, where one capacitor functions as both a detection and reference capacitor, reducing the number of electronic components and increasing robustness against external factors by using a recurrent charging and discharging method to calculate a measurement signal for hand presence detection across multiple areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single detection capacitor is used for multi-area detection, then device complexity is reduced, but measurement precision deteriorates due to inability to distinguish hand presence in specific areas
Solution Approach 1:
The detection area is segmented into multiple zones (first detection area and second detection area), each with its own detection capacitor. This allows the system to not only detect hand presence but also determine which specific area the hand is in, thereby maintaining measurement precision while managing device complexity through functional segmentation.
Solution Approach 2:
Each detection capacitor serves dual purposes: it detects hand presence in its specific area and also contributes to overall hand presence detection. The microcontroller analyzes signals from multiple capacitors to determine both presence and location, making the system multi-functional without requiring separate dedicated circuits for each function.
2Reliability
If traditional capacitive voltage divider is used, then hand presence detection is achieved, but reliability deteriorates due to false detection caused by external elements like moisture
Solution Approach 1:
The detection system is divided into multiple independent detection areas with separate capacitors. This segmentation allows the system to differentiate between moisture effects (which would affect all capacitors similarly) and actual hand presence (which would significantly affect only the capacitor in the hand's area), thereby improving reliability by enabling discrimination between true and false signals.
Solution Approach 2:
Each detection capacitor is optimized for its specific local area, creating localized detection zones. The microcontroller compares the relative changes in different capacitors to determine hand presence, leveraging the local quality of each sensor's response to distinguish between uniform environmental interference and localized hand contact.
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 solution decreases complexity and cost while enhancing robustness against external elements, allowing reliable multi-area hand presence detection with reduced electronic components and maintaining accuracy in the presence of moisture.
Implementation Method 1
the electrode forms a detection capacitor of predetermined value (expressed in farads). As a hand approaches this electrode, the apparent value of the detection capacitor increases and this increase may be used to detect the presence of a user's hand
Data Source
AI summary
A presence detection device including a sensor connected to a microcontroller, the sensor including a first detection capacitor arranged in a first detection area, and a second detection capacitor arranged in a second detection area. The microcontroller is configured to recurrently repeat a phase of measuring a measurement signal by charging/discharging the first detection capacitor from/into the second detection capacitor, and to detect a presence of a user in the first detection area and/or the second detection area according to the measurement signal. Also disclosed are a motor vehicle including a detection device and a detection method.