TOF Sensor Intrusion Detection Pixel Window Threshold
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Solution Overview
Problem
Current optical sensor devices face challenges in reliably detecting intrusion of objects within a monitored protective field due to measurement uncertainties and high probabilities of false alerts, especially when using time-of-flight (TOF) sensors, which require accurate distance determination to ensure safety and minimize unnecessary safety measures.
Innovation Solution
The implementation of a TOF sensor device that defines a pixel window comprising a subset of pixels, determines distance values for these pixels, and counts the number of values below a threshold to generate an indication of intrusion, optimizing detection probability while minimizing false alerts through filtering and outlier removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time-of-flight sensors are used for intrusion detection, then detection capability is improved, but false alert probability increases due to measurement uncertainties
Solution Approach 1:
The patent divides the detection task into segments by analyzing multiple individual pixel distance measurements rather than relying on a single measurement. Each pixel provides an independent distance measurement, and the system evaluates the distribution of these measurements to determine intrusion, thereby reducing the impact of measurement uncertainties and false alerts.
2Reliability
If a single pixel measurement is used for intrusion detection, then device complexity is reduced, but detection reliability decreases due to high false alert probability
Solution Approach 1:
The patent merges multiple individual pixel measurements into a collective evaluation. By combining the distance measurements from multiple pixels and analyzing their statistical distribution, the system achieves more reliable intrusion detection while maintaining relatively simple processing logic through counting measurements that fall within the protective field boundary.
3Reliability
If multiple distance values are evaluated with filtering and outlier removal, then false alerts are minimized, but processing time increases
Solution Approach 1:
The patent performs preliminary filtering and outlier removal on the distance measurements before the final intrusion determination. By pre-processing the data to remove obvious outliers and filter invalid measurements, the system reduces false alerts while keeping the main detection logic efficient and minimizing processing time for the critical decision-making step.
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 reliability of intrusion detection while reducing false alerts, ensuring high detection probability and maintaining system safety by accurately determining when an object is within the protective field, thus preventing unnecessary safety measures.
Implementation Method 1
time-of-flight (TOF) sensors, which require accurate distance determination
Data Source
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AI summary
A three-dimensional (3D) sensor device achieves high intrusion detection probability while keeping the probability of a false intrusion detection low by capturing a set of multiple spatial or temporal samples of a measured parameter for an object detected in the sensor's field of view. When an object is detected in the field of view, the TOF sensor device defines a window of N pixels comprising a subset of the pixels corresponding to the object, and obtains N distance measurements corresponding to the N pixels of the window. If the number of the N distance values that are less than a defined threshold distance is equal to or greater than a selected threshold value M (an integer less than N), the TOF sensor device determines that the object is intruding within a protective field and generates a suitable output.