Adaptive Smoothing for Ultrasound Fill Level Measurement
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Solution Overview
Problem
Existing level measurement technologies face challenges in accurately determining the fill level of filling materials, especially in difficult environments with rough or uneven surfaces, where noise and artifacts from parasitic echoes, container bottom echoes, or device-internal echoes can lead to errors and inaccuracies.
Innovation Solution
A method that adjusts the smoothing of the evaluation curve based on the measuring distance using varying filter strengths, employing techniques like moving average or sliding maximum value filtering, with reduced smoothing in close and far ranges to prevent artifacts and enhance precision, allowing for precise fill level determination across different measuring principles (ultrasound, pulse radar, and FMCW).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If strong smoothing is applied to the evaluation curve to reduce noise and artifacts, then measurement reliability improves, but measurement precision deteriorates due to loss of local maxima resolution
Solution Approach 1:
The patent applies different smoothing strengths to different regions of the evaluation curve. Strong smoothing is applied to regions with parasitic echoes (beginning and end regions) to improve reliability, while weak smoothing is applied to the central region to preserve measurement precision. This regional differentiation resolves the contradiction by making the smoothing strength adaptive to local signal characteristics.
Solution Approach 2:
The patent dynamically adjusts the smoothing strength based on the local characteristics of the evaluation curve. The smoothing parameter is not fixed but varies depending on the measured distance and local signal quality, allowing the system to optimize both reliability and precision adaptively across different measurement conditions.
2Reliability
If uniform smoothing is applied across all measuring distances, then noise reduction is consistent, but artifacts from parasitic echoes in specific regions cannot be effectively minimized
Solution Approach 1:
The patent identifies that different regions of the evaluation curve have different characteristics - the beginning and end regions contain parasitic echoes while the central region contains the primary measurement signal. By applying strong smoothing locally to the beginning and end regions and weak smoothing to the central region, the patent effectively minimizes parasitic echo artifacts while preserving measurement accuracy.
3Reliability
If high smoothing strength is used to eliminate artifacts, then measurement reliability improves, but the ability to resolve local maxima and determine precise fill level deteriorates
Solution Approach 1:
The patent applies strong smoothing only to specific regions where parasitic echoes occur (beginning and end regions of the evaluation curve), while applying weak smoothing to the central region where local maxima contain the primary measurement information. This selective approach eliminates artifacts without compromising the resolution of local maxima needed for precise fill level determination.
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 enables safe and precise fill level measurement by minimizing errors and noise, particularly in challenging environments, ensuring accurate determination of the fill level for a wide range of applications.
Implementation Method 1
ultrasound or radar-based measurement methods are predominantly used for continuous level measurement (in the context of this patent application, the term 'ultrasound' refers to sound waves in a frequency range between 14 kHz and 1 GHz)
Implementation Method 2
radar-based level measuring device operating according to the pulse-time-of-flight method (A radar-based level measuring device operating according to the pulse-time-of-flight method is described, for example, in published patent application DE 10 2012 104 858 A1)
Implementation Method 3
the pulse-time-of-flight measurement principle. Ultrasonic or microwave pulses are cyclically emitted toward the medium, and the time it takes to receive the corresponding echo pulse is measured
Implementation Method 4
it is known to smooth the evaluation curve using a suitable filtering method such as mean, maximum, or low-pass filtering
Implementation Method 5
A radar-based fill level measuring device whose evaluation curve is smoothed using a moving maximum value filter is shown, for example, in the German publication DE 10 2014 119 589 A1
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a method for reliably and precisely determining the fill level (L) of a filling material (3) in a container (2) by means of a fill level measuring device (1) based on ultrasound or radar. The method according to the invention is characterized in that the evaluation curve (A(d)) created on the basis of the reflected received signal (EHF) is smoothed by different amounts, depending on the measurement distance (d). The evaluation curve can thus be specifically filtered according to the application. Noise components and interference echoes can therefore be efficiently suppressed without unnecessarily limiting the accuracy of the fill level measurement.