Sensor Signal Filtering for Low-Latency Noise Reduction

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Solution Overview

Problem

Existing time-discrete filtering methods for sensor signals often compromise between noise reduction and signal latency, with conventional methods either reducing noise at the cost of higher latency or preserving edge steepness at the expense of noise reduction.

Innovation Solution

A method involving continuous filtering in the time domain, where each signal value is compared with two adjacent values, and replaced by a new value based on a value interval, optimizing noise reduction while maintaining high edge steepness without significant latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If complex filtering methods (e.g., frequency domain transformation, overlap-add methods) are used, then noise reduction is improved, but signal latency increases

Engineering Contradiction:
Improvenoise interferenceVSAvoidsignal latency
Core Design Contradiction:
Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent applies a segmented filtering approach by processing the sensor signal in discrete time steps, where each output value is determined independently by comparing the current input value with previous and future input values. This segmentation allows real-time processing without the need for complex frequency domain transformations, thereby reducing signal latency while maintaining noise reduction capabilities.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses a look-ahead buffer to store future input values that are needed for the filtering calculation. By preparing and storing these values in advance, the system can perform the comparison and determination operations without waiting for future data to arrive, thus reducing the overall signal latency while still achieving effective noise filtering.

Inventive Principle:
Principle #10Preliminary action

2Object-affected harmful factors

If standard time-discrete filters (e.g., median filter, mean filter) are used, then noise reduction is achieved, but edge steepness is reduced

Engineering Contradiction:
Improvenoise interferenceVSAvoidedge steepness
Core Design Contradiction:
Object-affected harmful factorsVSShape

Solution Approach 1:

The patent applies local quality by treating different regions of the signal differently based on their characteristics. The filtering operation adapts locally by comparing each input value with its neighbors and determining the output based on the local pattern. This allows the filter to preserve sharp edges where they occur while still reducing noise in smoother regions, achieving both noise reduction and edge preservation simultaneously.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

Instead of applying a conventional filter that smooths all regions uniformly, the patent inverts the approach by using the local variation pattern to determine the output. Rather than averaging or mediating all values, the method identifies and preserves significant local changes (edges) while filtering out noise, effectively doing the opposite of standard smoothing filters in terms of edge handling.

Inventive Principle:
Principle #13The other way round (Inversion)

3Measurement precision

If filtering is applied to reduce noise, then signal-to-noise ratio is improved, but detection time delay increases

Engineering Contradiction:
Improvesignal-to-noise ratioVSAvoiddetection time delay
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent makes the filtering system self-sufficient by using only the input signal values themselves for the filtering operation, without requiring external reference signals or complex adaptive parameters. The method determines each output value autonomously by comparing input values according to the defined rule, enabling real-time processing with minimal latency while achieving effective noise reduction and improved signal-to-noise ratio.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS12083667B2Method for filtering a sensor signal and device for controlling an actuator by filtering a sensor signal
Publication Date: 2024.09.10 EUROIMMUN MEDIZINISCHE LABORDIAGNOSTIKA
  • US12083667B2 patent drawing
  • US12083667B2 patent drawing
  • US12083667B2 patent drawing

AI summary

A method according to the invention is proposed for filtering a sensor signal, said method comprising various steps. A time-discrete sensor signal is provided as an input signal, and an output signal is generated via a continuous filtering of the input signal using a time-discrete filter in the time domain, which performs the following filter steps for each value of the input signal: comparing a specified signal value of a specified time index of the input signal with two further signal values of the input signal, wherein a first signal value of the two further signal values is temporally prior to the specified signal value and wherein a second signal value of the further signal values is temporally after the specified signal value, and replacing the specified signal value in the output signal by a new value in dependence on a value interval spanned by the two further signal values.