Light Grid Object Recognition via Segmented Evaluation Zones
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Solution Overview
Problem
Existing light grid monitoring systems in automated production environments struggle to distinguish between permitted and impermissible objects, often leading to complete shutdowns when multiple objects are present, requiring high installation effort and complex commissioning, and fail to differentiate between objects and personnel, resulting in safety vulnerabilities.
Innovation Solution
A method and light grid system that evaluates multiple criteria, including entry area, object size, distance, conveying speed, and direction, using a configuration tool to teach permitted objects and tolerate manufacturing tolerances, ensuring safe operation without complete shutdowns, even when multiple objects move through the monitoring area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light grid monitors multiple objects in a protective field, then object detection capability is improved, but the monitoring function is deactivated when multiple objects are present
Solution Approach 1:
The protective field is divided into multiple entry areas, and the light grid is segmented into multiple evaluation zones. Each zone can independently evaluate objects entering through its designated entry area, allowing multiple objects to be monitored simultaneously without deactivating the overall monitoring function.
Solution Approach 2:
Different criteria are assigned to different entry areas based on local requirements. Each entry area can have customized object size limits, speed thresholds, and distance parameters, allowing the system to accommodate multiple objects with different characteristics while maintaining safety.
2Measurement precision
If the light grid is configured to detect object size and position, then object identification is improved, but the system cannot handle multiple objects simultaneously
Solution Approach 1:
The light grid evaluates light barrier interruptions in multiple independent evaluation zones simultaneously. Each zone maintains full object identification capabilities (size, position, speed) while processing objects independently, enabling multiple objects to pass through the protective field without mutual interference.
Solution Approach 2:
The system evaluates more light barriers than strictly necessary for basic detection by dividing them into multiple evaluation zones. This excessive evaluation capability ensures that even when multiple objects are present, each object's characteristics can be fully assessed against the criteria.
3Productivity
If muting stations are used to allow material transport, then productivity is improved, but installation effort and commissioning complexity increase
Solution Approach 1:
The light grid serves multiple functions simultaneously: it acts as both a protective field monitor and a material transport authorizer. By configuring entry areas and criteria, the same device enables both safety monitoring and productive material flow without requiring separate muting station hardware.
Solution Approach 2:
The light grid's monitoring behavior dynamically adapts based on object characteristics. When objects meet the configured criteria (size, speed, position), the system automatically allows passage without manual muting intervention, reducing commissioning complexity while maintaining productivity.
4Reliability
If the light grid shuts down when objects are detected, then safety is improved, but system availability decreases
Solution Approach 1:
Safety criteria are applied locally to each entry area and evaluation zone rather than globally to the entire protective field. When an object violates criteria in one zone, only that zone triggers a shutdown, while other zones continue monitoring and allowing passage of compliant objects.
Solution Approach 2:
The system continuously evaluates object characteristics against configured criteria and provides real-time feedback. When objects consistently meet the criteria, the system maintains normal operation with high availability, while immediately shutting down only when criterion violations indicate genuine safety risks.
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
Enhances safety by accurately differentiating between permitted and impermissible objects, reducing false shutdowns and increasing system availability by allowing multiple objects to move without deactivating the monitoring function, while maintaining high safety standards through precise evaluation of object characteristics and movement parameters.
Implementation Method 1
a substantially horizontal light grid (10) with a plurality of parallel light barriers (20)
Data Source
Figure 1
Figure 2~3
AI summary
The method involves utilizing a horizontal light grid (10) with a number of light barriers (20) that are parallel to each other and monitoring subsequent three criteria such as access area for objects, size of the objects and distances between the objects. Maximum and minimum object dimension is monitored for each individual object or maximum conveying speed or conveying direction. A control signal is emitted during failure of one of the criteria. The light grid is operated in reduced resolution. An independent claim is also included for a light grid with a row of light transmitters.