Optoelectronic Safety Sensing With Redundant Multi-Core Processing
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Solution Overview
Problem
Optoelectronic safety devices face challenges in achieving high functional safety while minimizing costs, energy consumption, and complexity, particularly in signal processing and self-testing, due to the need for redundant systems and high-performance processors that are not readily available in high-performance classes.
Innovation Solution
An optoelectronic security device utilizing a standard multi-core processor on a single semiconductor substrate with a watchdog controller that monitors the system and can independently output safety signals, reducing the need for additional processor channels and minimizing costs and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-channel processor design with redundant computing units is used to achieve functional safety, then reliability is improved, but device complexity, installation space, costs, and waste heat increase
Solution Approach 1:
The processor is segmented into a single-channel sensor front end and a two-channel processor back end, with the coupling point clearly defined. This segmentation allows the use of a standard single-channel processor for the front end while achieving safety through the two-channel back end design.
Solution Approach 2:
A single standard processor is designed to perform multiple functions: it processes sensor data from the front end and simultaneously serves as one channel of the two-channel back end, while the other channel is provided by a second processor. This multi-functionality reduces the need for dedicated safety processors.
2Reliability
If dedicated lockstep dual-core processors optimized for safety applications are used, then common cause failures are eliminated and reliability is improved, but high performance classes are not available and adaptability is reduced
Solution Approach 1:
The invention merges a standard single-channel processor with a second processor to create a two-channel back end. The standard processor is coupled to provide one channel, while the second processor provides the other channel, achieving safety without requiring specialized lockstep dual-core processors.
3Reliability
If complete self-testing with redundant channels is performed to identify errors, then reliability is improved, but computing power requirements exceed those of the actual safety function
Solution Approach 1:
The system performs self-testing by having the second processor verify the operation of the first processor and the coupling between them. The watchdog unit monitors the system using the outputs from both channels, enabling the system to self-diagnose errors without requiring external testing resources.
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
This solution ensures functional safety with reduced costs and energy consumption by using a standard multi-core processor and watchdog controller, allowing for effective error identification and diagnosis, including common cause failures, while maintaining a low-profile and efficient design.
Implementation Method 1
a light transmitter (14) for emitting transmitted light beams (16) into a monitored area
Implementation Method 2
a light receiver (30) for generating received signals from received received light beams (26) which originate from reflections of the transmitted light beams (16)
Data Source
Figure 1~2
AI summary
The invention relates to an optoelectronic security device comprising a light transmitter (14) for emitting transmitting light beams (16) into a monitoring area (22), a light receiver (30) for generating received signals from received received light beams (26) originating from reflections of the transmitted light beams (16) on at least one object (24) in the monitoring area (22), an evaluation unit (32) for evaluating the received signals and for outputting a security signal depending on the received signals, wherein the evaluation unit (32) is a computing unit (42) configured as a standard multi-core processor, which is configured on only one semiconductor substrate and has at least two CPUs (44, 46), wherein the standard multi-core processor (42) is not a dedicated security component and the evaluation is performed redundantly on both CPUs (44 and 46) of the computing unit (42), and the evaluation unit (32) has a watchdog controller (50).which monitors the function of the computing unit (42), wherein the watchdog controller (50) can, independently of the computing unit (42), cause the evaluation unit (32) to output the safety signal.