Force Sensor Interdigitated Electrodes Multiaxial Precision
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Solution Overview
Problem
Existing force sensors struggle to measure horizontal forces with precision due to limited changes in capacitance caused by changes in electrode area, making it difficult to accurately detect external forces from various directions.
Innovation Solution
A force sensor design featuring a grounded conductor with a flat panel module, a protruding module, and strategically positioned electrodes, along with an elastic body, which measures capacitance changes between a first electrode and a second electrode to accurately detect vertical and horizontal forces, and a multiaxial force/torque sensor combining multiple sensors to derive forces and torques from various directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional electrode structure with parallel plates is used, then the structure is simple, but the changes in capacitance due to changes in area facing each other are not great, making it difficult to measure horizontal force with precision
Solution Approach 1:
The patent transitions from a conventional parallel plate electrode structure to a interdigitated electrode structure where electrodes are arranged in alternating fingers along one dimension. This dimensional reconfiguration increases the effective area facing each other when horizontal force is applied, thereby maximizing capacitance changes for horizontal force measurement while maintaining structural simplicity.
Solution Approach 2:
The patent optimizes parameters such as the number of electrode fingers, the width and spacing of each finger, and the overall geometry of the interdigitated electrodes. By carefully adjusting these parameters, the electrode structure achieves maximum capacitance sensitivity to horizontal force while keeping the device structure simple and manufacturable.
2Measurement precision
If electrodes are positioned close together to maximize capacitance changes, then measurement sensitivity improves, but electrodes may be easily separated by external impact
Solution Approach 1:
The patent employs curved or rounded electrode edges instead of sharp corners, and designs the electrode fingers with gradual transitions. This curvature reduces stress concentration points where cracks could initiate under external impact, thereby preventing electrode separation while maintaining close spacing for high measurement sensitivity.
Solution Approach 2:
The patent uses composite material structures for the electrodes, combining conductive materials with mechanically robust substrates or protective coatings. This composite approach ensures that electrodes remain closely spaced for sensitivity while the composite structure provides resistance to separation under external impact.
3Adaptability or versatility
If the ground unit is made movable to detect force, then force measurement capability is achieved, but the structure becomes more complex and vulnerable to impact
Solution Approach 1:
The patent designs the movable ground unit to serve multiple functions: it acts as the sensing element for force detection, provides electrical grounding, and serves as a mechanical support structure. This multi-functionality reduces overall device complexity while maintaining force detection capability.
Solution Approach 2:
The patent merges the ground unit with the elastic body and electrode support structure into an integrated assembly. By combining these components, the design reduces the number of separate parts and simplifies the overall structure while preserving the ability to detect force through ground unit movement.
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 precise measurement of both vertical and horizontal forces and multiaxial forces/torques by maximizing capacitance changes and preventing electrode separation from external impacts, improving the accuracy and reliability of force detection.
Implementation Method 1
a first electrode formed on an upper surface of the substrate, to generate a capacitance together with the flat panel module upon receiving power; and a second electrode formed on the substrate, to generate a capacitance together with the protruding module upon receiving power
Data Source
AI summary
Provided herein is a method and apparatus describing a force sensor that includes a ground unit that is a grounded conductor that changes its position according to an external force, and including a flat panel module that is a conductor of a flat panel shape, and a protruding module that is a conductor protruding from a lower surface of the flat panel module, a substrate of a flat panel shape arranged in a predetermined distance from the lower surface of the flat panel module, and having a hole through which the protruding module may be inserted, a first electrode formed on an upper surface of the substrate, to generate a capacitance together with the flat panel module upon receiving power, and a second electrode formed on the substrate, to generate a capacitance together with the protruding module upon receiving power.