Force Detection Apparatus with Dual-Layer Capacitance Linearization
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Solution Overview
Problem
Force detection apparatuses struggle to accurately detect forces across a wide range due to non-linear relationships between force and signal values, caused by differences in permittivity and deformation characteristics of air and cushion layers, resulting in an inflection point that disrupts linear detection.
Innovation Solution
A force detection apparatus with a first electrode and a second electrode separated by a deformable air layer and a cushion layer, where a force detection controller calculates a force signal value based on influence amounts from both capacitances, using an intermediate electrode to adjust capacitance calculations and ensure linear detection across varying force ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only an air layer is used between the first conductor and the second conductor, then weak force detection is favorable, but strong force cannot be detected because the air layer thickness reaches zero
Solution Approach 1:
The detection system is segmented into two distinct detection mechanisms: one based on air layer thickness change for weak force detection, and another based on cushion layer elastic deformation for strong force detection. This segmentation allows each mechanism to operate optimally within its respective force range, resolving the contradiction between weak force precision and strong force detectability.
Solution Approach 2:
The system uses a composite structure combining air (a compressible medium) and elastic cushion material. The air layer provides high sensitivity for weak forces, while the elastic cushion material provides continuous support and linear response for strong forces, creating a composite detection system that covers the full force range.
2Adaptability or versatility
If a cushion layer is added between the first conductor and the second conductor, then strong force detection is favorable, but the relationship between force and force signal value becomes non-linear due to different permittivity and deformation characteristics
Solution Approach 1:
The system dynamically switches between two detection modes based on the applied force magnitude. For weak forces, the air layer dominates the capacitance change providing linear response. For strong forces, the elastic cushion layer dominates providing continuous linear response. The force detection controller dynamically adapts the detection algorithm to maintain linearity across the entire force range.
Solution Approach 2:
The system changes the dominant physical parameter for detection based on force magnitude: at low forces, capacitance change due to air layer compression is measured; at high forces, capacitance change due to elastic cushion layer deformation is measured. This parameter switching maintains linear detection characteristics across the full force range.
3Adaptability or versatility
If both air layer and cushion layer are used together, then both weak and strong force detection is possible, but an inflection point occurs in the relationship between force and force signal value at the boundary between the two detection ranges
Solution Approach 1:
The force detection controller uses feedback from the capacitance measurement to determine which detection mode is active and applies the appropriate linearization algorithm. By monitoring the capacitance change pattern, the system identifies whether the air layer or cushion layer is the dominant deformation source and adjusts the detection algorithm accordingly, eliminating the inflection point and maintaining consistent linear detection characteristics.
Solution Approach 2:
The force detection controller acts as an intermediary that processes the raw capacitance signals from both layers and transforms them into a unified linear force measurement. It mediates between the two different physical mechanisms (air compression and elastic deformation) and produces a consistent force signal across the entire detection range, removing the discontinuity at the boundary.
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 enables continuous linear detection of forces from weak to strong applications by adjusting capacitance calculations, improving the accuracy and reliability of force detection.
Implementation Method 1
the capacitance between the first conductor and the second conductor is increased
Implementation Method 2
the cushion layer is elastically deformed according to the force
Data Source
AI summary
According to an aspect, a force detection apparatus includes: a first electrode facing an input surface to which an object to be detected applies a force; a second electrode facing the first electrode across a first layer deformable by the force; a conductor facing the second electrode across a second layer deformable by the force; and a force detection controller calculates a force signal value indicating the force, based on a first influence amount and a second influence amount, the first influence amount being an amount of influence added by the force to first capacitance between the first electrode and the second electrode, and the second influence amount being an amount of influence added by the force to second capacitance between the second electrode and the conductor.