Frequency-Multiplexed Touch Sensor Readout for Low-Latency Arrays
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Solution Overview
Problem
Existing tactile sensing arrays in robotics face challenges with low-resolution touch data and high latency due to serial sampling of touch sensors, which limits their precision and increases cost, especially when trying to achieve high spatial densities of read points.
Innovation Solution
A system with spatially distributed touch sensors sharing a signal medium, where each sensor outputs unique frequencies, and an analog-to-digital converter processes these signals using a fast Fourier transform to convert them into the frequency domain, allowing concurrent read-out and reducing the need for multiple microcontrollers, thereby increasing density and reducing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If serial sampling of touch sensors is used, then device complexity is reduced, but measurement precision and spatial density are limited
Solution Approach 1:
The patent transforms the sensor readout problem from the time domain to the frequency domain. Each touch sensor is assigned a unique frequency, and sensors are read concurrently through frequency multiplexing rather than sequential time-based sampling. This dimensional transformation enables high spatial density sensors to be read simultaneously without increasing time complexity, achieving both high measurement precision and manageable device complexity.
2Measurement precision
If multiple microcontrollers are used for high-density sensor arrays, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent makes a single microcontroller perform multiple functions by assigning it the task of reading all touch sensors through frequency multiplexing. Instead of requiring one microcontroller per sensor group, a single microcontroller with FFT capability can handle the entire sensor array by analyzing frequency components, thereby reducing device complexity while maintaining high spatial density measurement precision.
Solution Approach 2:
The patent replaces the mechanical/sequential approach of multiple microcontrollers physically managing sensor groups with a signal processing approach. By substituting hardware complexity with algorithmic processing (FFT), the system achieves high-density sensor reading capability using a single microcontroller, reducing both device complexity and cost.
3Loss of time
If concurrent read-out of sensors is implemented, then latency is reduced, but signal processing complexity increases
Solution Approach 1:
The patent replaces complex time-domain signal separation methods with frequency-domain processing using FFT. By transforming the concurrent sensor signals from time domain to frequency domain, the system can easily identify and separate individual sensor readings based on their unique frequency assignments, reducing latency while keeping signal processing complexity manageable through well-established FFT algorithms.
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
This approach enhances the precision and speed of tactile feedback processing, enabling higher spatial densities of touch sensing elements while minimizing cost and latency, improving the overall performance of robotic systems.
Implementation Method 1
an analog to digital converter electrically coupled to the signal medium and configured to receive the sets of frequencies from the touch sensors and convert the sets of frequencies to digital representations of the sets of frequencies in the time domain
Implementation Method 2
a processor communicatively coupled to the analog to digital converter and configured to execute a fast Fourier transform of the digital representations from the time domain into digital representations in the frequency domain
Data Source
AI summary
Provided is a system that includes: a plurality of touch sensors sharing a signal medium, each touch sensor in the plurality being configured to output set of frequencies on the signal medium responsive to being touched, each touch sensor in the plurality being configured to output a different set of frequencies; an analog to digital converter electrically coupled to the signal medium and configured to receive the sets of frequencies from the touch sensors and convert the sets of frequencies to digital representations of the sets of frequencies in the time domain; a processor communicatively coupled to the analog to digital converter and configured to execute a fast Fourier transform of the digital representations from the time domain into digital representations in the frequency domain; and an address decoder operative to transform the digital representations in the frequency domain into identifiers of touch sensors among the plurality of touch sensors.