Laser Scan Sensor Dynamic Threshold for Dirty Cover Detection
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Solution Overview
Problem
Conventional laser scanning sensors face issues with detection accuracy when the cover is unevenly dirty, particularly in cases where the measurement distance range is limited, leading to improper alerts and inability to detect distant human bodies.
Innovation Solution
The laser scanning sensor adjusts the detection threshold based on the distance information, allowing for reliable detection of distant human bodies and appropriate alerts even when the cover is unevenly dirty, by increasing the threshold for closer distance information and setting it differently for various ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed detection threshold is used for dirt detection, then detection is reliable for near-range objects, but distant human bodies cannot be detected when the measurement distance range is limited
Solution Approach 1:
The patent implements a dynamic detection threshold that automatically adjusts based on the measured distance to objects. The threshold is higher for near-range measurements and lower for distant measurements, allowing the system to maintain reliable dirt detection for nearby objects while also being able to detect distant human bodies when the measurement distance range is limited.
Solution Approach 2:
The patent changes the detection threshold parameter according to the distance information obtained from the laser range finder. By making the threshold a variable parameter that depends on distance rather than a fixed value, the system can adapt to different measurement ranges and object distances, resolving the contradiction between near-range dirt detection accuracy and distant human body detection reliability.
2Reliability
If the detection threshold is lowered to detect distant objects, then distant human bodies can be detected, but false alerts occur due to cover dirt
Solution Approach 1:
The system uses a dynamic threshold adjustment mechanism where the detection threshold is automatically raised for near-range measurements. This prevents false alerts caused by cover dirt while maintaining the ability to detect distant human bodies, as the threshold is only lowered when measuring distant objects where human body detection is the priority.
Solution Approach 2:
The detection threshold parameter is changed based on the distance to the measured object. When objects are detected at distances indicating they are likely human bodies (beyond a certain range), the threshold is lowered to enable detection. When objects are near the sensor, the threshold is raised to prevent false dirt detection alerts, thus resolving the contradiction between detecting distant objects and avoiding false alerts.
3Ease of operation
If a single threshold value is used for all measurement directions, then the system is simple to operate, but improper alerts occur when measurement distance range is limited in certain directions
Solution Approach 1:
The patent segments the detection space into different distance ranges (near-range and distant ranges) and applies different threshold values to each segment. This segmentation is automatically performed by the control unit based on the distance information from the laser range finder, maintaining ease of operation while improving alert accuracy for limited measurement distance ranges in certain directions.
Solution Approach 2:
The system uses feedback from the laser range finder's distance measurements to automatically adjust the detection threshold. The control unit continuously monitors the distance to detected objects and adjusts the threshold accordingly, providing accurate alerts without requiring manual configuration for different measurement directions or ranges.
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 ensures reliable detection of distant human bodies and prevents false alerts due to cover dirt, while providing accurate alerts for unevenly dirty covers, enhancing the sensor's performance in both near and extended measurement ranges.
Implementation Method 1
a laser light emitting portion for emitting laser light to outside of the housing through the cover
Implementation Method 2
a laser light receiving portion for receiving laser light and outputting a signal according the amount of the received light
Implementation Method 3
perform measurement by acquiring distance information to at least one object through measurement of a period of time taken for reflected light caused by the laser light being reflected by the object to return
Data Source
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AI summary
A laser scanning sensor (100) of an embodiment of the present invention includes a laser range finder (110), a scanning mechanism (120), a data acquisition portion (130), a dirt determination portion (140), an alert output control portion (150) and a memory (160). The laser range finder (110) is arranged inside a housing (101) having an opening portion, and the opening portion is covered with a lens cover (116) that can transmit laser light. In the dirt determination portion (140), a predetermined threshold to be compared with a received light level is changed based on maximum detection distance information in each measurement direction.