3D Sensor Arrangement for Automatic Machine Safety Restart
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Solution Overview
Problem
Current safety arrangements for machines, particularly industrial robots, require manual intervention for restarting after a safety-directed shutdown, leading to reduced productivity and increased downtime.
Innovation Solution
A sensor arrangement using a 3D camera with a control and evaluation unit that records and analyzes 3D images to create a reference map, identifies moving objects, and distinguishes between static objects and persons, enabling automatic restart of the machine when the monitored zone is clear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual restart is required after safety shutdown, then safety reliability is improved, but productivity deteriorates due to downtime
Solution Approach 1:
The sensor arrangement automatically monitors the monitored zone and performs self-verification to determine when restart conditions are met, eliminating the need for manual intervention. The system serves itself by continuously evaluating safety conditions and autonomously enabling restart when safe, thus resolving the contradiction between safety reliability and productivity.
Solution Approach 2:
The system performs preliminary monitoring and evaluation of the monitored zone before allowing restart. By pre-checking safety conditions and maintaining readiness to verify zone clearance, the system prepares restart conditions in advance, reducing downtime while maintaining safety standards.
2Measurement precision
If manual restart is required, then safety monitoring accuracy is improved, but availability deteriorates
Solution Approach 1:
The sensor arrangement autonomously performs safety monitoring and self-verification, maintaining high measurement precision while eliminating the need for manual intervention. The system independently evaluates whether the monitored zone is clear and autonomously enables restart, thus improving availability without sacrificing monitoring accuracy.
Solution Approach 2:
The system continuously monitors the monitored zone and provides feedback on safety conditions. By maintaining continuous feedback loops that detect objects and evaluate restart conditions, the system ensures high monitoring accuracy while enabling rapid automatic restart when safe, thereby improving availability.
3Reliability
If protected zones are configured large, then safety coverage is improved, but productivity deteriorates due to early shutdown
Solution Approach 1:
The system applies different evaluation criteria to different regions within the monitored zone. By using 3D sensor data to distinguish between static objects (like pallets) and dynamic objects (persons), the system locally adapts its safety evaluation, allowing restart when only static objects are present even in large protected zones, thus improving productivity without reducing safety coverage.
Solution Approach 2:
The system changes the parameter of object classification from binary (present/absent) to multi-state (static object/dynamic object/person). By evaluating additional parameters such as object position, size, and movement characteristics from 3D sensor data, the system can differentiate between harmless static objects and persons requiring shutdown, enabling restart in large protected zones when appropriate, thus improving productivity while maintaining safety coverage.
Data Source
AI summary
The invention relates to a sensor arrangement and to a method for safeguarding a monitored zone at a machine. The sensor arrangement comprises a camera continuously generating 3D images, a control and evaluation unit for the position detection of objects in the monitored zone and, in the case of a hazardous position, initiating a safety-directed response of the machine, with a buffer memory unit being provided for storing last recorded images and with a 3D reference map being prepared from the stored images when the safety-directed response was initiated, a voxel identification unit being provided for flagging those voxels in the current 3D image whose coordinates differ by a specified distance from those of the corresponding voxels of the reference map, a movement recognition unit being provided in which the voxels thus identified are examined as to whether they display position changes that are above a fixed threshold in the course of a fixed number of further current images, and independently thereof, a restart signal for the machine being able to be output at an output.