Safety-Critical Control Architecture With Self- and Cross-Checks
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Solution Overview
Problem
Current safety-critical systems, such as those for fully or partially automated vehicle control, face challenges in detecting and handling malfunctions effectively, leading to potential property damage or personal injury, and existing redundancy methods are costly and require complex hardware.
Innovation Solution
A control system incorporating self-check and cross-check logic units to detect malfunctions, allowing for reduced redundancy and improved diagnostic coverage, utilizing diverse control functions and hardware platforms to enhance error detection and handling, thereby reducing hardware costs and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple nominally identical, independent control functions are used with majority principle, then reliability is improved, but device complexity increases
Solution Approach 1:
The monitoring task is segmented into two distinct logical units: self-check logic units that monitor individual control functions, and cross-check logic units that compare outputs across multiple control functions. This segmentation allows each unit to perform a specialized monitoring function rather than requiring full redundancy of complete control functions.
Solution Approach 2:
The self-check and cross-check logic units act as intermediary monitoring layers between the control functions and the final output. These intermediaries detect malfunctions by analyzing control function outputs and internal states, preventing direct propagation of errors while allowing the control functions to operate independently.
2Reliability
If redundant control functions are implemented, then reliability is improved, but hardware cost increases
Solution Approach 1:
Instead of creating full hardware copies of control functions for redundancy, the patent uses software-based self-check and cross-check logic units that copy and analyze the output data and internal states of control functions. This virtual copying approach provides monitoring capability without duplicating the expensive hardware infrastructure.
Solution Approach 2:
The self-check and cross-check logic units serve multiple functions: they monitor individual control functions, compare outputs across functions, detect systematic and random errors, and trigger appropriate responses. This multi-functionality consolidates what would otherwise require separate dedicated monitoring hardware into unified logic units.
3Reliability
If self-check and cross-check logic units are used, then diagnostic coverage is improved, but control system complexity increases
Solution Approach 1:
The control functions perform self-monitoring through self-check logic units that examine their own output data and internal states. This self-service approach allows each control function to detect its own malfunctions without requiring external monitoring infrastructure, simplifying the overall system architecture.
Solution Approach 2:
The cross-check logic units receive feedback from multiple control functions and their self-check units, comparing outputs to detect inconsistencies. This feedback mechanism enables detection of systematic errors that affect multiple control functions simultaneously, with the cross-check logic providing continuous monitoring feedback to maintain system safety.
Data Source
AI summary
A control system for at least one receiving device includes at least one input interface, a plurality of control functions, a self-check logic unit, at least one cross-check logic unit, and at least one output interface. The at least one input interface is configured to read in an input to be reacted to by controlling the receiving device. The plurality of control functions are each configured to determine output data for the actuator from an input which has been read in. The self-check logic unit is for each control function and is configured to detect a malfunction of the control function. The at least one cross-check logic unit is configured to check whether output data determined by a control function are consistent with (i) output data determined by another control function, (ii) internal information from the other control function, and/or (iii) an input used by the other control function.