Laser Scanner Reference-Contour Monitoring for SIL3 Level Crossings
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Solution Overview
Problem
Existing laser scanner systems for level crossings fail to meet Safety Integrity Level 3 (SIL3) due to unreliable detection of objects, particularly shiny or black objects, and are prone to false triggering under adverse weather conditions, lacking comprehensive certification for high safety standards.
Innovation Solution
A system using a laser scanner with a deflection unit and evaluation unit that defines a contour field in front of a reference contour, detecting objects by the absence of reflections from this contour field, ensuring reliable detection regardless of object reflectance properties and weather conditions, and incorporating redundant scanners for enhanced safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional laser scanners are used to detect objects at level crossings, then the system can identify objects in the field of view, but the detection reliability deteriorates for objects with extreme reflectance properties (black or shiny objects)
Solution Approach 1:
The patent introduces a reference contour as an intermediary element. Instead of directly detecting the target object (which may have problematic reflectance properties), the system detects the reference contour that is always visible in the field of view. The presence or absence of the reference contour serves as a reliable indicator of system functionality and object detection capability, regardless of the target object's reflectance characteristics.
Solution Approach 2:
The system continuously monitors the reference contour and uses this information as feedback to determine system status. By evaluating whether the reference contour is detected, the system can infer whether objects are present in the monitoring area, creating a reliable feedback mechanism that works independently of target object properties.
2Reliability
If safety measures such as redundant electronics and function monitoring are implemented in laser scanners, then the system meets safety standards like EN13849 and EN61496, but the device complexity increases
Solution Approach 1:
The patent extracts the safety-critical detection function from the complex redundant electronics and isolates it into a simple reference contour monitoring mechanism. By focusing solely on detecting the presence or absence of the reference contour, the system achieves safety functionality without requiring multiple redundant scanner units or complex electronic evaluation systems.
Solution Approach 2:
Instead of using complex redundant systems to prove safety through multiple detection channels, the patent inverts the approach by using a single simple detection channel (reference contour monitoring) to guarantee safety. The simplicity of the reference contour method inherently provides safety without requiring proof through redundancy.
3Adaptability or versatility
If laser scanners are used outdoors exposed to environmental influences like fog, rain and snow, then the system can monitor level crossings, but false triggering increases due to adverse weather conditions
Solution Approach 1:
The patent converts the potential harm of environmental influences into a benefit by using the reference contour as a stable reference that remains detectable under various weather conditions. The reference contour serves as a constant marker that helps distinguish between actual objects and environmental interference, thereby reducing false triggering while maintaining outdoor operation capability.
4Productivity
If a contour field boundary is defined in front of the reference contour to create a contour field, then the system can define a monitoring zone between the reference contour and the boundary, but the measurement precision requirements increase
Solution Approach 1:
The patent applies partial action by monitoring only the reference contour rather than attempting to precisely measure all objects in the entire field of view. By focusing detection efforts on the reference contour and using its presence/absence to infer object presence in the contour field, the system achieves broad monitoring coverage without requiring high measurement precision across the entire area.
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
Ensures reliable detection of all objects within the contour field, preventing false triggers and maintaining safety integrity by defaulting to a safe state in case of detection failure, thereby achieving SIL3 safety standards.
Implementation Method 1
A light beam generated by a laser is directed into a field of view via a light deflection unit, where it is reflected or remitted by any object present. The reflected or remitted light returns to the laser scanning unit and is detected there by a receiver.
Implementation Method 2
If the propagation time of, for example, pulsed laser light is also monitored, the propagation time can be used to determine the distance of the object from the laser scanner and thus the location of the object in the field of view using the speed of light.
Implementation Method 3
The light deflection unit is usually designed to be pivotable or rotatable, so that the light beam generated by the laser sweeps across a field of view created by the rotational movement.
Data Source
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AI summary
The invention relates to a system for monitoring a level crossing (16) comprising a laser scanner (10), an evaluation unit (112), and naturally occurring objects (18, 18-1, 18-2, 18-3, 18-5) in the field of view (14) and within the range of view of the laser scanner (10), which form a reference contour (20, 20-1, 20-2, 20-3) and limit the field of view (14), wherein a contour field boundary (22) can be defined in the evaluation unit (112), which, as seen from the laser scanner (10), lies in front of the reference contour (20, 20-1, 20-2, 20-3) and which defines a contour field (24, 24-1, 24-2, 24-3) between the reference contour (20, 20-1, 20-2, 20-3) and the contour field boundary (22) defined and which is freely definable in its form, wherein the level crossing (16) lies between the laser scanner (10) and the contour field (24, 24-1, 24-2, 24-3) and the evaluation unit (112) is configured to output a safety signal at a safety output (116),when the laser scanner (10) does not receive a reflection signal (106) from the reference contour (20, 20-1, 20-2, 20-3) or from the contour field (24, 24-1, 24-2, 24-3) when scanning over the level crossing (16).