Protected Zone Monitoring for Automatic Safety Reset
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Solution Overview
Problem
Existing systems for monitoring protected zones for object infringement lack high availability and efficient management of mechanically movable parts, leading to potential hazards and reduced productivity.
Innovation Solution
A system with multiple sensors and a controller that monitors a plurality of protected zones, ensuring a predetermined sequence of entry and exit to prevent hazardous situations while allowing continuous operation of movable parts, using laser scanners or 3D cameras for contactless detection and generating release signals based on predetermined incident orders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single protected zone is monitored, then the system structure is simple, but the productivity is reduced due to frequent stoppages for manual resets
Solution Approach 1:
The monitored area is divided into multiple protected zones (first protected zone, second protected zone, third protected zone, fourth protected zone) arranged in sequence. This segmentation allows the system to track objects through multiple zones and determine whether they have properly exited the hazard area, enabling automatic reset functionality that improves productivity without requiring manual intervention after false alarms.
Solution Approach 2:
The system pre-configures the sequence of protected zones and establishes the expected exit path before operation begins. By having the zones arranged in a predetermined sequence (first→second→third→fourth), the system can automatically determine when an object has safely left the hazard area, allowing automatic reset without manual intervention and thus improving productivity.
2Reliability
If multiple protected zones are monitored with sequence detection, then the availability is improved through automatic reset, but the device complexity increases
Solution Approach 1:
The control unit continuously receives signals from sensors monitoring each protected zone and uses this feedback to determine the current state of the system. By evaluating the sequence of zone infringements and releases, the control unit can automatically detect when an object has properly exited the hazard area and generate a release signal to reset the safety system, thereby improving availability through automatic reset functionality.
Solution Approach 2:
The control unit serves multiple functions: it monitors all protected zones, determines infringement sequences, identifies when objects have left protected zones, generates stop signals for hazardous situations, and issues release signals for automatic reset. This multi-functionality consolidates what could be multiple separate devices into a single control unit, improving availability while limiting the increase in device complexity.
3Reliability
If the mechanically movable part is stopped on every protected zone infringement, then the safety is ensured, but the productivity is reduced
Solution Approach 1:
The control unit dynamically adjusts the system response based on the specific infringement pattern detected. Instead of a static stop-on-any-infringement approach, the system evaluates the sequence of zone violations and applies different responses: stopping the mechanically movable part for direct hazard infringements (first or third zone) while allowing continued operation for indirect infringements (second or fourth zone) when the object has properly exited the hazard area, thus maintaining safety while improving productivity.
Solution Approach 2:
Different protected zones have different safety criticality levels. The first and third protected zones (directly adjacent to working zones) are treated as high-criticality zones requiring immediate stoppage upon infringement. The second and fourth protected zones (indirectly adjacent) are treated as lower-criticality zones where infringement alone does not require stoppage if the object has properly exited through the correct sequence, thereby optimizing the balance between safety and productivity.
4Productivity
If indirect protected zones are excluded from stop conditions, then the productivity is improved, but the safety risk increases
Solution Approach 1:
The system pre-configures the sequence of protected zones and establishes the expected exit path before operation begins. By having the zones arranged in a predetermined sequence (first→second→third→fourth), the system can automatically determine when an object has safely left the hazard area, allowing automatic reset without manual intervention and thus improving productivity.
Solution Approach 2:
The control unit continuously receives signals from sensors monitoring each protected zone and uses this feedback to determine the current state of the system. By evaluating the sequence of zone infringements and releases, the control unit can automatically detect when an object has properly exited the hazard area and generate a release signal to reset the safety system, thereby improving availability through automatic reset functionality.
Data Source
AI summary
A method and a system have at least one sensor for monitoring a plurality of protected zones for infringement by at least one object. A controller controls a plant to be safeguarded having a mechanically movable part, having the sensor for the at least planar monitoring of the protected zones by a control and evaluation unit for evaluating. The received signals of the sensor determine which of the protected zones has been infringed by the object and which protected zone the object has left. The controller generates and outputs a switch signal that is a release signal for the release of the plant operation. The mechanically movable part is either in a first working zone or in a second working zone, with the first working zone and the second working zone each being associated with a first protected zone and a second protected zone, respectively.