Forward Scatter Sensor Droplet Size Verification

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Solution Overview

Problem

Existing forward scatter sensors for meteorological applications face limitations in accuracy and reliability, especially during low-intensity precipitation events and are prone to degradation due to environmental conditions and misalignment, which affects their measurement performance.

Innovation Solution

A forward scatter sensor system that emits a light sheet and captures scattered light to identify double peaks representing precipitation droplets, estimating droplet sizes based on peak magnitudes and residence times, with a control entity verifying analysis performance and invoking maintenance actions when discrepancies exceed thresholds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of stationary object

If forward scatter sensor operates continuously in field conditions for several years, then it provides continuous meteorological measurements, but environmental conditions cause gradual soiling and wear of optical components which degrades measurement accuracy and reliability

Engineering Contradiction:
Improveoperational durationVSAvoidmeasurement accuracy
Core Design Contradiction:
Duration of action of stationary objectVSReliability

Solution Approach 1:

The system performs preliminary verification of analysis performance by comparing droplet size estimates from different methods (double peak analysis vs. residence time analysis) before final precipitation analysis. This preliminary check detects degradation early and triggers maintenance actions to restore measurement accuracy before significant degradation occurs.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements continuous feedback through verification of analysis performance, where measurement results are monitored and compared against expected patterns. When degradation is detected through inconsistent droplet size estimates, the system triggers maintenance actions and adjusts operation to maintain reliability throughout extended operational periods.

Inventive Principle:
Principle #23Feedback

2Productivity

If forward scatter sensor operates in field conditions, then it enables meteorological measurements, but external impacts affect alignment between transmitter and receiver which compromises measurement performance

Engineering Contradiction:
Improvemeasurement capabilityVSAvoidalignment accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The system performs preliminary verification checks that include detecting alignment issues before they significantly compromise measurements. By continuously monitoring measurement signals for patterns indicating misalignment, the system can trigger realignment actions proactively.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements self-diagnosis capabilities where the analyzer automatically detects alignment problems through verification of analysis performance and triggers maintenance actions without external intervention, enabling the sensor to maintain measurement precision through self-correcting mechanisms.

Inventive Principle:
Principle #25Self-service

3Productivity

If forward scatter sensor uses conventional precipitation analysis methods, then it provides basic precipitation detection, but it provides limited capability for detailed analysis of precipitation and limited accuracy especially at low intensity precipitation events

Engineering Contradiction:
Improveprecipitation detection capabilityVSAvoidprecipitation analysis accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The system segments the precipitation analysis into multiple independent methods: double peak identification for droplet detection, residence time analysis for size estimation, and verification procedures for quality control. This segmentation allows each method to optimize for specific aspects of precipitation analysis, improving overall accuracy especially for low intensity events where individual methods may have limitations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system implements multiple analysis methods that can handle different precipitation types and intensities universally. The verification mechanism works across all precipitation conditions, and the system can switch between or combine analysis methods depending on the specific measurement conditions, providing both broad applicability and high precision.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 accuracy and reliability of precipitation analysis by accurately detecting droplet sizes and types, improving measurement consistency and reducing the need for frequent maintenance due to environmental factors.

Implementation Method 1

The measurements carried out using a forward scatter sensor are based on analysis of the light scattered from particles in the atmosphere: a transmitter sends a conical light beam towards a receiver such that it is offset from a direct path between the transmitter and the receiver, whereas the receiver captures light scattered from the particles in the atmosphere.

Methodology Applied
Scientific EffectLight scattering: Scattering

Data Source

PatentEP3633415B1A forward scatter sensor
Publication Date: 2021.04.14 VAISALA
  • EP3633415B1 patent drawingFigure 1A~1B
  • EP3633415B1 patent drawingFigure 2~4
  • EP3633415B1 patent drawingFigure 3A~3B

AI summary

According to an example embodiment, a forward scatter sensor for precipitation analysis is provided, the forward scatter sensor comprising: a transmitter arranged to emit a light sheet; a receiver offset from a propagation path of the light sheet and arranged to observe light scattered from particles that fall through a measurement volume defined by an intersection of the propagation path of the light sheet and a field of view of the receiver; and a control entity comprising an analyzer arranged to record a measurement signal that is descriptive of intensity of light captured by the receiver as a function of time, wherein the analyzer is further arranged to: carry out a precipitation analysis on basis of a time segment of the measurement signal, the analysis comprising identifying, in said time segment of the measurement signal, one or more double peaks that each represent a respective droplet and comprise a first peak that represents light refracted from the bottom of the respective droplet upon entry to the measurement volume and a second peak that represents light reflected from the top of the respective droplet upon exit from the measurement volume; carry out a verification of analysis performance based on magnitudes of first peaks of at least one identified double peak and on respective residence times for said at least one identified double peak, wherein the residence time for a given double peak is defined by a time difference between the first and second peaks of the given double peak; and invoke a predefined maintenance action in response to said verification indicating a threshold-exceeding difference between respective size estimates derived based on magnitudes of the first peak of said at least one identified double peak and based on residence times of said at least one identified double peak.