Multiplexed Inductive Tactile Sensor Array Design
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Solution Overview
Problem
Existing tactile sensors face challenges such as susceptibility to electromagnetic noise, complexity in electrical connections, and limited scalability, especially in harsh environments and when deployed in arrays, leading to issues like crosstalk and noise interference.
Innovation Solution
A multiplexed inductive tactile sensor design with conductive targets and compressible dielectric layers, along with alternating coil windings, reduces electromagnetic noise and simplifies electrical connections, enabling improved array scalability and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inductive tactile sensors use traditional electrical connections between sensels and circuitry, then signal transmission is achieved, but the complexity of electrical connections increases and noise and crosstalk are introduced
Solution Approach 1:
The patent replaces traditional electrical wire connections with wireless communication between sensels and the external controller. Each sensel contains a transmitter that wirelessly transmits measurement data and receives control signals, eliminating the need for physical electrical connections and thereby reducing connection complexity and associated noise/crosstalk while maintaining reliable signal transmission.
2Area of stationary object
If the array is scaled up in number of sensels, then measurement coverage is improved, but the complexity of electrical connections and noise/crosstalk increase significantly
Solution Approach 1:
By implementing wireless communication in each sensel, the patent enables scalable array expansion without proportionally increasing connection complexity. Each sensel operates independently with its own transmitter, allowing the array to be scaled to larger areas while maintaining manageable system complexity and reducing noise/crosstalk issues associated with dense electrical interconnections.
3Object-affected harmful factors
If traditional inductive tactile sensors are used, then fluid and contaminant tolerance is achieved, but the change in inductance is small requiring complicated electronic circuitry
Solution Approach 1:
The patent combines multiple functions within each sensel unit: the inductive sensing element, the wireless transmitter, and the measurement circuitry are integrated into a single compact module. This integration allows the sensel to maintain fluid and contaminant tolerance while providing sufficient inductance change signal strength, eliminating the need for separate complicated electronic circuitry while preserving environmental resistance.
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 design enhances resistance to electromagnetic noise, allows operation in harsh conditions, and improves scalability and reliability of tactile sensor arrays by reducing the number of electrical connections and minimizing crosstalk.
Implementation Method 1
Inductive sensels have an electric coil and an embedded metal target in front of the coil. When external mechanical force displaces the metal target against the coil an eddy current in the metal target changes and as a result the inductance of the coil changes.
Implementation Method 2
When external mechanical force displaces the metal target against the coil an eddy current in the metal target changes and as a result the inductance of the coil changes.
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A multiplexed inductive tactile sensor for measuring location and force of contact with an external object includes sense and drive electronics and an array of sensels, each having a drive coil inductively coupled with a sense coil. The array has rows and columns of sensels. Drive coils in each column are electrically connected in series and driven by an AC constant current source through an analog demultiplexer. All sense coils in each row are electrically connected in series and the induced AC voltage across the row is fed to an AC amplifier through an analog multiplexer. The amplified AC voltage is then fed to the amplitude demodulator to generate a DC signal that is dependent on the inductive coupling factor between drive coil and sense coil of a sensel that is selected by being the intersection of the active current drive column and sense row.