Time of Flight Sensor Histogram Summation for Object Detection
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Solution Overview
Problem
Time of flight sensors face challenges in accurately detecting objects, especially poorly reflecting ones, due to low signal-to-noise ratios, which obscure object classes within ambient noise, making it difficult to distinguish between object and noise photons.
Innovation Solution
The method involves generating and summing histograms from a time of flight sensor to enhance the distinction between object and ambient noise photons by adding successive histograms, analyzing the summed histogram to detect object presence, and using a queue to store and process these histograms, ensuring only consistent scene configurations are considered.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed threshold is used to identify object classes in the histogram, then the detection process is simple, but the detection reliability deteriorates when the signal-to-noise ratio is low
Solution Approach 1:
The patent applies preliminary action by accumulating multiple histograms before performing the final detection. Instead of using a single histogram with a fixed threshold, the system accumulates N histograms and only performs detection after a certain number of successful detections, thereby preparing sufficient data in advance to overcome low signal-to-noise ratio conditions
Solution Approach 2:
The patent implements continuity of useful action through continuous histogram accumulation and detection. The system continuously monitors and accumulates histograms over time, maintaining detection capability even when individual measurements are noisy, thereby ensuring reliable detection without requiring complex processing of each individual histogram
2Measurement precision
If multiple histograms are accumulated and summed, then the distinction between object and noise photons is improved, but the processing complexity increases
Solution Approach 1:
The patent applies merging by combining multiple histograms into a single summed histogram. Instead of processing N separate histograms, the system merges them into one accumulated structure, reducing the complexity of individual processing steps while maintaining the benefits of multiple measurements for improved detection precision
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 improves the reliability and detection range of objects by clearly differentiating object photons from ambient noise in the summed histogram, providing a more robust and accurate detection method.
Implementation Method 1
A time of flight sensor is a sensor using the propagation of light to measure distances between objects and this sensor
Implementation Method 2
measure a time of flight, that is to say the time that passes between the emission of this radiation and its reception by the sensor after the reflection of the radiation on the object
Implementation Method 3
The radiation reception can be accomplished using sensitive single photon detectors. Single photon avalanche diodes, commonly referred to by the person skilled in the art by the acronym 'SPAD', are known in particular as single photon sensitive detectors
Data Source
AI summary
In an embodiment a method for detecting a presence of at least one object in a field of view of a time of flight sensor includes successively generating, by the time of flight sensor, histograms, each histogram comprising several classes associating a number of photons detected at a given acquisition period, adding several successively generated histograms so as to obtain a summed histogram and analyzing the summed histogram to detect the presence of at least one object in the field of view of the time of flight sensor.