Safety Laser Scanner Reference Target for Outdoor Reliability
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Solution Overview
Problem
Safety laser scanners used in outdoor environments face reliability issues due to soft targets like rain, fog, and air pollution, which reduce detection accuracy and lead to unpredictable responses, as they interfere with the transmission and reflection of light signals, making it difficult to reliably detect objects within the monitored area.
Innovation Solution
The method involves using an external reference target with a minimum target reflectance calculated based on the scanner's distance-dependent reception characteristic, allowing the scanner to adjust its detection capability according to current visibility conditions, and using natural surfaces as reference targets, eliminating the need for separate installations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If safety laser scanners are used in outdoor environments, then object detection capability is provided, but detection reliability deteriorates due to soft targets like rain, fog, and air pollution interfering with light transmission and reflection
Solution Approach 1:
The patent introduces a reference target as an intermediary object with known reflectance properties. By comparing the reflected light signal from the reference target against expected values, the system can detect and compensate for attenuation caused by soft targets (rain, fog, pollution) in the atmosphere, thereby maintaining detection reliability despite these harmful environmental factors
Solution Approach 2:
The system implements feedback by continuously monitoring the signal strength from the reference target and using this information to adjust detection thresholds or compensate for atmospheric attenuation. This feedback mechanism allows the scanner to adapt to changing environmental conditions and maintain reliable object detection despite interference from soft targets
2Reliability
If transmission radiation is dampened by soft targets, then visibility is reduced, but this leads to objects in the protected area not being detected
Solution Approach 1:
The reference target serves as a mediator to measure the actual visibility conditions by detecting how much the soft targets attenuate the light signal. This measured attenuation information is then used to compensate for the reduced visibility, allowing the system to maintain reliable object detection even when visibility is degraded by environmental factors
Solution Approach 2:
The system changes detection parameters (such as threshold values or sensitivity settings) based on the measured visibility conditions from the reference target. When soft targets cause signal dampening, the system adjusts its detection parameters to account for the reduced illumination intensity, ensuring objects remain detectable despite visibility reduction
3Reliability
If backscattered signal from soft targets exceeds evaluation threshold, then false object detection occurs, but this increases false alarms
Solution Approach 1:
The reference target acts as a mediator to establish the baseline signal characteristics under current atmospheric conditions. By comparing actual object signals against this reference-based baseline, the system can distinguish between legitimate object reflections and spurious backscatter from soft targets, thereby reducing false alarms while maintaining detection accuracy
Solution Approach 2:
The system dynamically adjusts evaluation thresholds based on the reference target measurements. When soft targets increase background backscatter, the system raises the detection threshold accordingly, preventing false alarms caused by excessive backscatter while still maintaining the ability to detect actual objects
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 object detection even in adverse outdoor conditions by defining the detection capability and increasing the availability of the scanner, preventing false alarms and ensuring compliance with safety standards.
Implementation Method 1
Receiving the transmitted light beam reflected on objects in the field of view with a light receiver
Implementation Method 2
periodic scanning of a field of view of the scanner including a monitored area with the transmitted light beam via a deflection unit
Implementation Method 3
If, for example, the propagation time of individual laser light pulses from the emission to the reception of a reflection on the object is also monitored, the distance of the object from the laser scanner can also be deduced from the propagation time using the speed of light
Data Source
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AI summary
The invention relates to a method for the reliable detection and positioning of objects in a monitoring area using an optoelectronic scanner, comprising the steps of: - emitting a light beam with a light transmitter and - periodically scanning a viewing area of the scanner encompassing the monitoring area with the light beam via a deflection unit; - receiving the light beam reflected by objects in the viewing area with a light receiver and providing received signals whose signal amplitudes correspond to the received light intensities, - outputting a safety signal (warning or shutdown signal) when an unauthorized object is detected in the monitoring area, - providing an external reference target in the viewing area, - acquiring the actual signal amplitude of the reflections from the reference target, characterized by, - calculating a target signal amplitude for the reference target.which corresponds to a minimum target reflectance of the reference target, from the measured distance to the reference target, a scanner-specific, distance-dependent reception characteristic of the light receiver, and the currently measured received signal at the reference target during commissioning; - output of an error signal if a drop below the target reference target signal level is detected during operation. This enables reliable detection capability, especially in outdoor applications.