Scanning Distance Measurement Signal Processing for False Detection Reduction
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Solution Overview
Problem
Scanning-type distance measurement devices face challenges in accurately determining the presence of a monitored object due to erroneous detection of reflected light from tiny objects, such as dust or insects, or from other devices, leading to potential false safety shutdowns.
Innovation Solution
A signal processing device that consecutively calculates distances at specific scan angles over multiple scans, using a correlation relationship between measurement light and reflected light, to differentiate between actual monitored objects and transient or smaller objects, and outputs a detection signal only when consistent distances are measured across multiple scans.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the distance measurement device detects reflected light from any object in the scan range, then the detection sensitivity is improved, but false detection increases due to tiny objects like dust or insects
Solution Approach 1:
The patent applies preliminary action by performing distance calculations for multiple scans (first scan and second scan) before making a final detection determination. The detection determination unit waits to confirm the same distance is measured in consecutive scans before triggering an alarm, preventing false detections from transient objects like dust or insects while maintaining sensitivity to actual threats.
2Speed
If the device triggers an alarm on any detected object, then the response speed is improved, but unnecessary machine shutdowns occur due to false detections
Solution Approach 1:
The patent implements feedback by using the distance measurement results from the first scan to inform the detection determination in the second scan. The determination unit compares consecutive distance measurements and only triggers an alarm when the distance remains consistent across multiple scans, providing feedback-based verification that eliminates false alarms while maintaining rapid response to genuine objects.
3Area of stationary object
If the device scans the entire to-be-monitored region continuously, then the coverage area is improved, but the measurement time increases
Solution Approach 1:
The patent applies periodic action by scanning the to-be-monitored region at predetermined scan cycles and performing distance calculations at specific scan angles in a periodic manner. This allows the system to maintain comprehensive coverage while reducing the computational burden by only processing measurements at selected angles and times, thereby managing measurement time effectively.
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 significantly reduces erroneous detections, ensuring that only actual monitored objects trigger detection signals, thereby preventing unnecessary machine shutdowns.
Implementation Method 1
calculating a distance D from a scanning type distance measurement device to an object located in a to-be-monitored region in accordance with a detection time difference Δt between pulse-shaped measurement light emitted to the to-be-monitored region and reflected light from the object with respect to the measurement light
Implementation Method 2
calculating a distance D from a scanning-type distance measurement device to an object located in a to-be-monitored region in accordance with a phase difference Δφ between measurement light that is modulated in amplitude and emitted to the to-be-monitored region and reflected light from the object with respect to the measurement light
Implementation Method 3
detect reflected light from an object with respect to the measurement light
Data Source
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AI summary
Provided are a signal processing device of a scanning-type distance measurement device, etc., which can determine correctly whether the reflection light from an object is a to-be-monitored object that is actually to be detected. A signal processing device of a scanning-type distance measurement device comprises: a distance calculation unit (230) for, on the basis of a predetermined correlation relationship between measured light and reflection light, calculating, for each predetermined scan angle, the distance from the scanning-type distance measurement device to an object; a to-be-monitored object determination unit (231) for performing a to-be-monitored object determination process, in which, when the distance calculation unit calculates a distance within a to-be-monitored region for N number of scans (N is an integer equal to or greater than 2) consecutively in a specific scan angle direction, it is determined that there is an object to be monitored in the specific scan angle direction; and a signal output unit (24) which, when it is determined by the to-be-monitored object determination unit that there is an object to be monitored, outputs a to-be-monitored object detection signal.