Analog Input Ternary State Translation for Functional Safety Fault Detection
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Solution Overview
Problem
Existing data communication systems between machines fail to meet functional safety standards, particularly in noisy environments, leading to potential catastrophic failures due to undetectable errors, which are exacerbated when scaled across fleets of machines.
Innovation Solution
Implementing multiple microcontrollers with application processors to ensure redundant processing and encoding of safety messages, using ternary state translation and fault indicators to detect bit overwrite errors, and commanding machines to a safe state upon error detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple microcontrollers with redundant processing are implemented to detect errors, then reliability is improved, but device complexity increases
Solution Approach 1:
The system divides the safety-critical processing into separate microcontrollers (dual microcontroller architecture). Each microcontroller independently processes safety messages and determines safety states, allowing error detection through comparison of results without requiring a completely complex monolithic system.
Solution Approach 2:
The patent implements redundant processing by having multiple microcontrollers perform the same safety message processing independently. The results are then compared to detect errors, using the copying principle to achieve reliability without proportionally increasing overall system complexity.
2Measurement precision
If encoding is performed on data to detect bit overwrite errors, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system uses encoding schemes that provide feedback mechanisms for error detection. By encoding safety messages and comparing encoded values against expected values, the system achieves high measurement precision in detecting bit overwrite errors while managing processing overhead through efficient encoding algorithms.
3Reliability
If functional safety standards are strictly enforced with error thresholds, then reliability is improved, but productivity decreases
Solution Approach 1:
The patent changes the parameter of error detection from continuous monitoring to discrete threshold-based detection. By establishing specific error thresholds and using discrete safety state determinations, the system maintains strict functional safety compliance while avoiding the continuous processing overhead that would reduce communication productivity.
4Reliability
If redundant processing is used to compare results and detect errors, then reliability is improved, but loss of time increases
Solution Approach 1:
The system performs preliminary encoding of safety messages before transmission and comparison. By pre-processing and encoding data in advance, the redundant processing required for error detection is optimized to minimize additional time loss while maintaining high reliability through comprehensive error checking.
Data Source
AI summary
A safety module having a plurality of microcontrollers receives an analog input and determines a value of the analog input. The microcontrollers each determine a respective ternary state of the device by identifying, from three candidate ranges of values, a range of values in which the value falls, wherein at least two of the plurality of microcontrollers uses different candidate ranges of values, determining, based on the identified range, a ternary state corresponding to the range, and assigning the determined ternary state as the respective ternary state. The safety module determines whether the ternary states from the two microcontrollers map to a fault state, and, where they do, cause a command a command to be output to the device to enter a safe state.