ToF Container Measurement Using First-Bin Histogram Extraction
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Solution Overview
Problem
Time-of-flight (ToF) sensors struggle to accurately determine physical quantities, such as container height and fill level, in the presence of reflective containers due to weak signals from the container rim and multiple reflections, leading to overestimated distances and underestimated heights.
Innovation Solution
A method and system using a time-of-flight sensor to process histograms by extracting a first bin characterizing the rising pulse edge, enhancing the signal for determining physical quantities, and employing a multi-zone ToF sensor for two-dimensional calculations, including interpolation and distortion correction to refine measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all histogram bins are processed to determine container physical quantities, then complete distance information is obtained, but measurement precision deteriorates due to inclusion of multi-reflected photons causing overestimated distances
Solution Approach 1:
The patent extracts only the first histogram bin characterizing the rising pulse edge from the complete histogram data, separating the useful signal (directly reflected photons) from harmful information (multi-reflected photons). This extraction principle resolves the contradiction by discarding overestimated distance information while preserving accurate container height measurement data.
Solution Approach 2:
The patent segments the histogram into distinct parts: the first bin representing the rising edge with useful signal, and subsequent bins containing multi-reflected photons. By processing only the relevant segment (first bin), the method achieves precise measurements without being contaminated by erroneous distance data from other segments.
2Measurement precision
If the complete histogram signal is used for measurement, then all reflected photons are considered, but measurement precision deteriorates due to weak rim signals being overwhelmed by strong internal reflections
Solution Approach 1:
The patent converts the harmful effect of multiple reflections into a beneficial selection criterion. By identifying that multi-reflected photons arrive at later time intervals, the method uses this temporal characteristic to filter them out, keeping only the first bin data where the useful rim reflection signal dominates. The harmful factor (multiple reflections) actually helps identify which data to discard.
3Reliability
If standard histogram processing is used, then all distance data is captured, but reliability deteriorates due to overestimated distances from multi-reflected photons
Solution Approach 1:
The patent extracts only the reliable first bin data from the histogram, removing unreliable distance measurements from multi-reflected photons. This extraction ensures that only trustworthy data (where light traveled the shortest path) is used for determining container physical quantities, thereby improving measurement reliability.
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
Improves the accuracy of determining container dimensions and position, enabling precise control of beverage dispensing by filtering out noise and reflections, and allowing for real-time fill level detection.
Implementation Method 1
A ToF ranging system uses a ToF imager to measure the distance to an object (e.g., a target). To measure an object, the ToF ranging system instructs the ToF sensor to send a light signal (e.g., light pulses such as a laser or infrared light) toward the object and measures the time it takes for the signal to reach the object and return to the ToF imager.
Implementation Method 2
A single-photon avalanche diode (SPAD) can be used as a reflected light detector. In some applications, an array or matrix of SPADs is provided as a sensor (referred to as a SPAD matrix) to detect a reflected light pulse. A reflected photon can generate a carrier wave in the SPAD via the photoelectric effect.
Implementation Method 3
the reception of at least one histogram generated from a light pulse emitted by a time-of-flight sensor and reflected by the container
Data Source
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AI summary
According to one aspect, a method is proposed for measuring a physical quantity (HEIGHT, LEVEL, DIAMETER, X0, Y0) of a container (12) placed in a detection zone (DET), using a time-of-flight sensor (100). The method comprises, by means of a processor (107B), the following steps: receiving (300) a histogram (H, HD) or even a matrix of histograms (MATRIX, DIFFMATRIX) generated from a light pulse emitted by a time-of-flight sensor and reflected by the container, each histogram (H, HD) being formed of bins (Bj) corresponding to distinct times of flight; extracting (310), from each histogram, a first histogram bin (FSB) characterizing first a rising edge of the pulse, so as to obtain a matrix of first histogram bins (MFSB); and determine (320) the height, diameter, position of the container and/or the filling height of the container from the matrix of first bins of histograms.