Three-Electrode Capacitive Sensor for Reliable Remote Object Detection
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Solution Overview
Problem
Capacitive sensors struggle with long-range detection of dielectric and conductive objects, particularly when these objects are weakly or not coupled to the environment or reference potential, limiting their effectiveness in applications like machine protection and human-robot collaboration.
Innovation Solution
A three-electrode capacitive sensor device is introduced, where a third electrode is connected to the reference potential and arranged within the electrical field, enabling capacitive coupling with objects to detect changes in displacement current even at a distance, thereby enhancing detection range and independence from environmental coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a two-electrode capacitive sensor is used for long-range detection, then the detection range is extended, but the reliability of detection deteriorates when objects are weakly or not coupled to the reference potential
Solution Approach 1:
The sensor is divided into three separate electrodes (first electrode for field generation, second electrode for field reception, third electrode for reference potential coupling) instead of using only two electrodes. This segmentation allows each electrode to have a specialized function, enabling reliable long-range detection by providing an additional reference potential coupling path through the third electrode.
2Length of stationary object
If the electrode area is increased to improve long-range detection, then the detection range is extended, but the device complexity and cost increase
Solution Approach 1:
The solution moves from a one-dimensional approach (increasing electrode area) to a three-dimensional spatial arrangement by adding a third electrode in the cyclically coaxial configuration. This dimensional change allows the system to achieve extended detection range through spatial optimization rather than simply scaling up electrode size, thereby avoiding increased device complexity and cost.
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 three-electrode configuration allows for reliable detection of objects across a larger range, improves functional safety by avoiding non-recognition due to poor coupling, and enables smaller electrode sizes and spacings while reducing costs and simplifying integration, thus enhancing safety and efficiency in safety-related systems.
Implementation Method 1
a first electrode (102) and a signal generation device (120) which applies an electrical signal to this first electrode (102), causing the first electrode (102) to emit an electric field (E)
Implementation Method 2
a second electrode (104), which is spaced apart from the first electrode (102) and which serves to receive the electric field (E) emitted by the first electrode (102)
Implementation Method 3
the sensor device has a third electrode (106) which is connected to a reference potential of the sensor device. The third electrode (106) is arranged in the electric field (E) generated or emitted by the sensor device
Data Source
Figure 1~2
Figure 3~4
Figure 5~6b
AI summary
A capacitive sensor device (2) for detecting objects (50), wherein the sensor device comprises a first electrode (22) and a signal generation device (20) which applies an electrical signal (S1) to this first electrode (22), causing the first electrode (22) to emit an electric field (E1), and a second electrode (24), which is spaced apart from the first electrode (22), for receiving the electric field (E1) emitted by the first electrode (22). According to the invention, the sensor device (2) comprises a third electrode (26), which is supplied with a reference potential of the sensor device.