Capacitive Sensor Electrode Layout for Shear Force Measurement
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Solution Overview
Problem
Conventional electrostatic capacitance detection devices can only measure ground contact pressure distribution in the Z-axis direction and are unable to detect shear force components in the XY-axes directions, limiting the accuracy of ground contact condition assessment for tires and similar objects.
Innovation Solution
An electrostatic capacitance detection device with a first electrode, an insulating layer, and a second electrode, where the second electrode is deformed by shear force, allowing for the calculation of shear force by detecting changes in electrostatic capacitance values, and featuring a substrate with a Poisson ratio of 0 to 0.48 and gradation in the insulating layer for improved accuracy and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional electrostatic capacitance detection device with linear electrodes is used, then the device structure is simple and easy to manufacture, but it can only measure ground contact pressure in the Z-axis direction and cannot detect shear force components in the XY-axes directions
Solution Approach 1:
The patent transitions from conventional linear electrodes to a matrix arrangement of first and second electrodes in the XY-plane, adding dimensional capability to detect shear forces in multiple directions while maintaining the electrostatic capacitance measurement principle
Solution Approach 2:
The detection surface is divided into multiple discrete electrode pairs (first electrodes and second electrodes) arranged in a matrix pattern, allowing independent measurement at each intersection point to map the complete shear force distribution across the contact area
2Loss of information
If resin with electric resistance decreasing with deformation is used, then the measurement mechanism is simple, but it cannot capture oblique stress components and provides incomplete ground contact information
Solution Approach 1:
The electrostatic capacitance detection device is designed to perform multiple measurement functions simultaneously: it can detect both normal pressure (Z-axis) and shear forces (XY-axes directions) using the same basic sensor structure and measurement principle
Solution Approach 2:
The patent replaces the conventional resistance-based mechanical deformation detection with electrostatic capacitance measurement, using the deformation of the insulating layer to change capacitance values between electrode pairs, thereby detecting shear forces through electrical field changes rather than mechanical resistance changes
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 the measurement of both Z-axis pressure distribution and shear force in XY-axes directions, providing a comprehensive assessment of ground contact conditions, enhancing the accuracy and durability of the detection device.
Implementation Method 1
an electrostatic capacitance detection device with a first electrode, an insulating layer, and a second electrode, where the second electrode is deformed by shear force, allowing for the calculation of shear force by detecting changes in electrostatic capacitance values
Implementation Method 2
a substrate with a Poisson ratio of 0 to 0.48
Data Source
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AI summary
A conventional electrostatic capacitance detection device has a problem that a highly accurate pressure distribution is difficult to measure. Further, stress in the plane direction (X, Y directions) parallel to the plane, that is, shear force cannot be detected. Solution means By configuring an electrostatic capacitance detection device in which a first electrode is formed, an insulating layer is formed on the first electrode, and a second electrode is formed on the insulating layer, a shear force applied from above an upper portion of the second electrode can be calculated. Further, the material and configuration of the insulating layer are improved, the patterns of the first electrode and the second electrode are improved, and an individual AC drive circuit is connected to the first electrode. Thus, highly accurate measurement of the shear force can be made. Furthermore, a temperature sensor is provided so that correction by temperature can be made. In addition, by configuring a frame portion not being present in either one of two directions orthogonal to the surroundings of a sensing unit of the electrode, and thus the length can be increased.