Imaging Sensor Safety Verification Using Projected Test Patterns
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Solution Overview
Problem
Existing safety systems using imaging sensors face challenges in achieving fail-safe configurations, making it difficult to implement them in safety-critical applications due to the complexity and cost of ensuring the reliability of camera systems.
Innovation Solution
An apparatus and method that utilize a test unit with a processing and projection unit to verify the operability of imaging sensors, allowing standard, non-fail-safe cameras to be used by projecting patterns and evaluating their properties, thereby ensuring the imaging sensors provide fail-safe input for safety functions without the need for redundant designs or runtime tests.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If standard imaging sensors are used for safety functions, then flexibility and adaptability are improved, but reliability is worsened because they are not sufficiently fail-safe
Solution Approach 1:
A test unit with projection unit and processing unit is introduced as an intermediary between the standard imaging sensor and the safety function. The projection unit projects test patterns into the monitoring area, and the processing unit verifies that the imaging sensor correctly detects these patterns, thereby mediating the reliability issue while allowing standard sensors to be used
Solution Approach 2:
The system performs preliminary verification of the imaging sensor's operability by continuously monitoring whether it correctly detects projected test patterns. This preliminary check ensures the sensor is functioning properly before it is used for safety-critical detection, preventing unreliable sensors from compromising safety
2Reliability
If redundant designs are implemented to ensure fail-safe operation, then reliability is improved, but device complexity is worsened
Solution Approach 1:
The safety verification function is extracted from the imaging sensor itself and placed in a separate test unit. This allows standard, simple imaging sensors to be used while the complexity of safety verification is handled independently by the projection unit and processing unit, avoiding the need for complex redundant sensor designs
3Reliability
If runtime tests are performed to verify sensor operability, then reliability is improved, but productivity is worsened due to additional processing time
Solution Approach 1:
The verification of imaging sensor operability is performed continuously in the background through the test unit projecting and detecting patterns, without interrupting the main safety monitoring function. This continuous parallel operation ensures reliability verification occurs without sacrificing productivity
Data Source
AI summary
An apparatus and method for executing a safety function is particularly applicable to monitoring a safety area of a technical installation. An imaging unit acquires an event that triggers the safety function within a defined working area. A controller carries out a safety-related reaction depending on the triggering event. A test unit is configured to verify the operability of the imaging unit and includes a processing unit and a projection unit. The projection unit projects a pattern with defined properties into the working area. The processing unit evaluates the image data acquired by the imaging unit to detect the projected pattern within the acquired image data. Further, the processing unit extracts the specific properties of the detected projected pattern, and compares the specific properties of the detected projected pattern with the defined properties.