Laser Scanning Sensor Mirror Detection Logic
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Solution Overview
Problem
Conventional laser scanning sensors fail to detect intruders who use mirrors to divert reflected light, leading to alarm failures, as they determine the absence of objects when no reflected light is received.
Innovation Solution
A laser scanning sensor with a mirror surface determination unit that analyzes distance data to identify continuous measurement directions with significantly different readings, determining the presence of a reflecting surface and distinguishing it from human bodies, thereby preventing false alarms by outputting specific alarm signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the laser scanning sensor determines the absence of objects when no reflected light is received, then the detection simplicity is improved, but the reliability deteriorates due to alarm failures when intruders use mirrors to divert reflected light
Solution Approach 1:
The system changes the detection parameter from binary presence/absence to analyzing the spatial distribution pattern of detected objects. By examining whether detected objects form continuous patterns across multiple measurement directions, the system can distinguish between actual objects and mirror reflections, thereby maintaining detection simplicity while improving reliability and reducing alarm failures
Solution Approach 2:
The patent replaces the simple reflected light detection mechanism with a more sophisticated analysis mechanism that examines the spatial distribution and continuity of detected objects across multiple measurement directions. This substitution allows the system to identify mirror reflections by their discontinuous patterns while maintaining automated operation
2Reliability
If the sensor analyzes distance data to identify mirror surfaces by detecting continuous measurement directions with significantly different readings, then the reliability is improved, but the device complexity increases due to additional determination units and processing
Solution Approach 1:
The determination unit is segmented into distinct functional components: a mirror surface determination unit that identifies reflecting surfaces by analyzing continuous measurement directions with significantly different readings, and a human body determination unit that identifies actual intruders. This segmentation allows complex analysis to be broken down into manageable, specialized functions that improve reliability without overwhelming system complexity
Solution Approach 2:
The system introduces an intermediary mirror surface determination unit that acts as a mediator between the raw distance data acquisition and the final human body detection. This intermediary unit pre-processes the data by identifying and flagging mirror surfaces, thereby simplifying the subsequent human body detection process and managing overall system complexity
3Loss of information
If the sensor outputs specific alarm signals for mirror surface detection versus human body detection, then the information quality is improved, but the device complexity increases due to multiple alarm signal output units
Solution Approach 1:
The alarm signal output structure implements local quality by providing different types of alarm signals for different detection scenarios: one alarm signal type for mirror surface detection and another for human body detection. This allows the system to preserve detailed information about the nature of detected objects while keeping the alarm output structure manageable through localized, context-appropriate responses
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
The sensor effectively detects intruders using mirrors, reducing alarm failures by accurately distinguishing mirror reflections from human presence, ensuring reliable detection and alerting mechanisms.
Implementation Method 1
measures a distance to at least one object present in a direction of the laser beam, based on a time until the laser beam reflects off the at least one object and returns to the laser distance meter
Implementation Method 2
the laser beam reflects off the at least one object and returns to the laser distance meter
Data Source
AI summary
A laser scanning sensor includes a distance data acquisition unit which acquires distance information in each measurement direction, and a memory which stores, as background distance information, a distance of an outer periphery of the detection area in each measurement direction. The sensor also includes a mirror surface determination unit which determines the presence of a reflecting surface when the distance information in continuous measurement directions is greater by at least a predetermined distance than the corresponding background distance information, and when this state changes thereafter by at least a predetermined rate in a predetermined time, a human body determination unit which extracts a portion of the distance information that may correspond to a human body and determines whether it corresponds to a human body, and an alarm output control unit which outputs an alarm signal when the presence of the reflecting surface or the human body is confirmed.