Multicapacitor Force Sensor Arrays for 6-DOF Moment Detection
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Solution Overview
Problem
Existing multicapacitor sensor arrays are limited in their ability to detect all six components of forces and moments, primarily failing to sense moments in the Z-axis and other orientations effectively.
Innovation Solution
A multicapacitor sensor system is designed with a drive plate and a sensor plate separated by a compressible dielectric material, featuring orthogonal electrodes and radially extending electrodes to detect forces in X, Y, and Z directions, along with moments around the Z-axis, enabling a 3-axis load cell with 6 degrees of freedom. This system includes electrical circuitry to process capacitance changes and differentiate between forces and moments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional capacitive sensor array with parallel conductors is used, then lateral force detection in X and Y directions is enabled, but moment detection in Z-axis and full 6-degree-of-freedom sensing is not achieved
Solution Approach 1:
The sensor array is segmented into multiple capacitor elements with specific geometric arrangements. Each capacitor element consists of conductive plates separated by dielectric material, with segments positioned to detect different force and moment components. This segmentation enables independent measurement of each of the six degrees of freedom components.
Solution Approach 2:
The patent transitions from a two-dimensional parallel conductor arrangement to a three-dimensional capacitor array configuration. Conductive plates are positioned at different heights and orientations, creating capacitance measurement volumes that extend in multiple spatial dimensions. This dimensional expansion enables detection of moments about all three axes and forces in all three directions.
2Ease of manufacture
If the sensor array layout is simplified for ease of manufacture, then production cost decreases, but the ability to sense all six components of forces and moments is lost
Solution Approach 1:
The capacitor array structure is designed to perform multiple sensing functions simultaneously. The same physical structure detects both lateral forces and moments, eliminating the need for separate sensor systems. Each capacitor element contributes to multiple measurement equations, providing full 6-DOF sensing capability from a unified structure.
Solution Approach 2:
The patent utilizes changes in dielectric properties and capacitor geometry parameters to enable different sensing modes. By varying plate area, separation distance, and orientation, the same physical structure can detect different force and moment components, achieving multi-functionality without requiring multiple separate sensor arrays.
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 system effectively measures all six components of forces and moments, providing a full 3-axis load cell with 6 degrees of freedom, suitable for various applications including MEMS configurations and harsh environments, by accurately detecting changes in capacitance to determine applied forces and moments.
Implementation Method 1
a first and second plurality of parallel conductors separated by a compressible insulator... capacitance between the first and second conductors to change
Implementation Method 2
A compressible, elastic dielectric material separates the drive and sensor patterns
Implementation Method 3
forces applied perpendicular to the planes causes the insulator to compress
Implementation Method 4
A compressible, elastic dielectric material separates the drive and sensor patterns
Data Source
AI summary
A multicapacitor sensor system facilitates the measurement of applied shear and moment forces. In one disclosed configuration, moments may be detectable in x, y and z directions, resulting in a full, 3-axis load cell with 6 degrees of freedom. The system may further include electrical circuitry to generate electrical drive pulses, sense amplify and buffer the voltages induced on the sense plates, and compute applied forces. An array of multicapacitor sensors that can be addressed individually without cross-talk and globally produce a map of forces and moments applied to the whole array. A MEMS implementation enables in vivo application.