Safety Program Evaluation System for Functional Safety Verification
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods do not provide an effective system for inspecting and evaluating the functional safety of safety programs executed in safety controllers, which is crucial for ensuring the safety of machines in manufacturing sites.
Innovation Solution
An evaluation system that includes program execution, comparison, and analysis functions to determine if the output signals from a safety program match expected values, with support for generating evaluation conditions and identifying errors, allowing for automatic inspection of safety programs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a safety program is executed in a safety controller, then the machine operation can be controlled, but the functional safety of the program cannot be confirmed without manual inspection
Solution Approach 1:
The patent creates a copy of the safety program's processing logic in the evaluation system. The evaluation system executes the same safety program separately and compares its output with the original system's output. This copying approach allows automated verification of functional safety without adding complex physical inspection equipment to the actual safety controller.
Solution Approach 2:
The evaluation system acts as an intermediary between the safety controller and the verification process. Instead of directly inspecting the safety controller's internal state, the evaluation system receives the same input signals, processes them through a copy of the safety program, and compares results. This intermediary approach simplifies the verification mechanism while maintaining reliability.
2Productivity
If manual inspection methods are used to verify safety programs, then the system complexity remains low, but the evaluation efficiency and accuracy are insufficient
Solution Approach 1:
The evaluation system performs self-verification by executing a copy of the safety program and comparing its own output with the original system's output. The system automatically generates evaluation results without requiring external manual inspection, thereby improving evaluation efficiency while keeping the added complexity minimal.
Solution Approach 2:
The evaluation system implements a feedback mechanism where the output of the safety program is continuously monitored and compared against expected results. When discrepancies are detected, the system provides feedback about the functional safety status, enabling automated and efficient verification without complex manual intervention.
3Reliability
If the safety program output is not verified against expected values, then the system operation is simple, but the functional safety cannot be ensured
Solution Approach 1:
The evaluation system performs preliminary verification by pre-defining expected output values for given input signals. Before actual safety-critical operations, the system evaluates whether the safety program produces correct outputs for test inputs, ensuring functional safety is established in advance without complicating the main operation.
Solution Approach 2:
The verification process uses a copy of the safety program logic to generate expected output values, which are then compared with the actual safety controller's output. This copying method automates the verification process, maintaining ease of operation while ensuring reliability through systematic comparison of program behavior.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An evaluation system (1) includes process execution means (154) for executing a safety program (10), setting means (156) for receiving an evaluation condition including: an input signal to be evaluated; an output signal to be evaluated; and an expected output value, first determination means (156, 154, 158) for changing the value of the input signal, from an initial first input value to a second input value, and determining whether a first output value of the output signal which is determined by the process execution means (156, 154, 158) is identical to the expected output value, second determination means (156, 154, 158) for restoring the value of the input signal, from the second input value to the first input value, and determining whether a second output value of the output signal is identical to the first output value, and output means (160) for outputting a determination result.