ToF Histogram Edge Detection for Reflective Container Measurement
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Solution Overview
Problem
ToF sensors struggle to accurately determine physical quantities, such as container height and filling level, in reflective containers like glass or polished materials due to low reflection from the upper rim and multiple reflections inside, leading to overestimation of distances and underestimation of height.
Innovation Solution
A method and system using a time-of-flight sensor to enhance the useful signal by selecting the first histogram bin indicating a pulse rising edge, discarding multi-reflected photons, and employing matrix-based interpolation and noise filtering to improve measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a ToF sensor is used to measure container height, then the measurement process is simple and fast, but the measurement precision deteriorates due to multiple reflections inside reflective containers
Solution Approach 1:
The patent segments the histogram data into multiple bins representing different time-of-flight ranges. By analyzing the distribution of photons across these segmented bins and identifying the first significant bin (indicating the rising edge of the pulse), the system can distinguish between direct reflections from the container rim and multiple internal reflections, thereby improving measurement precision while maintaining the fast processing capability of ToF sensors.
2Quantity of substance
If photons from multiple reflections inside the container are included in the measurement, then more signal data is available, but the measurement precision deteriorates due to overestimation of distance
Solution Approach 1:
The patent extracts and isolates the useful signal by identifying the first histogram bin that indicates the rising edge of the reflected light pulse. This extraction method separates the useful photons (those reflecting from the container rim) from the harmful multiple reflections inside the container. By focusing only on the first significant bin and discarding subsequent bins that represent multiple reflections, the system improves distance measurement accuracy while still utilizing the available photon data.
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
Enhances the estimation of physical quantities like container height and filling level, enabling precise monitoring and automation of beverage dispensers by accurately determining container dimensions and position.
Implementation Method 1
A ToF telemetry system uses a ToF imager to measure the distance of an object (for example, a target). To measure an object, the ToF telemetry system asks the ToF sensor to send a light signal (for example, light pulses such as a laser or an infrared light) towards the object and measures the time needed by the signal to reach the object and return back to the ToF imager.
Implementation Method 2
A single-photon avalanche diode (SPAD) may be used as a reflected light detector. In some applications, a network or array of SPADs is provided as a sensor (hereinbelow SPAD array) in order to detect a reflected light pulse. A reflected photon could generate a carrier wave in the SPAD by photoelectric effect.
Implementation Method 3
The carrier wave generated by the photon could trigger an avalanche current in one or more SPAD(s) of a SPAD array. The avalanche current could signal an event, namely that a photon has been detected.
Data Source
AI summary
According to one aspect, a method is provided for measuring a physical quantity of a container placed in a detection area, using a time-of-flight sensor. The method comprises, using a processor, receiving a histogram or a matrix of histograms generated from a light pulse emitted by a time-of-flight sensor and reflected by the container, each histogram being formed of bins corresponding to distinct times of flight, extracting, for each histogram, a first histogram bin that indicates a pulse rising edge, so as to obtain a matrix of first histogram bins, and determining the height, the diameter, the position of the container and/or the filling height of the container from the matrix of first histogram bins.