Dual-Microcomputer Control Diagnostics With Parallel Result Comparison
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Solution Overview
Problem
Current controlling apparatuses for industrial products using dual microcomputers for functional safety require longer diagnostic times and increased memory capacity due to separate diagnostic processes for each CPU, which complicates effective program sequence and hardware access diagnostics.
Innovation Solution
Implementing a system where both microcomputers run the same controlling and diagnostic programs parallelly, with one CPU writing diagnostic results to a shared memory area and comparing them with its own results to identify errors, and varying diagnostic program sequences every 4n bytes to enhance diagnostic capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each microcomputer performs diagnostic functions separately, then diagnostic coverage is complete, but diagnostic time increases and memory capacity requirements increase
Solution Approach 1:
The patent merges the diagnostic processes of two microcomputers by having them execute the same diagnostic program simultaneously and compare results. Instead of performing separate diagnostic cycles, both CPUs run diagnostics in parallel and cross-verify their results through inter-CPU comparison, thereby maintaining complete diagnostic coverage while halving the total diagnostic time required.
Solution Approach 2:
The diagnostic function is made continuous through parallel execution. While one CPU performs its diagnostic routine, the other CPU simultaneously performs its own diagnostic routine. This continuous parallel operation ensures that diagnostic coverage remains complete while eliminating the sequential time penalty that would otherwise be incurred.
2Reliability
If each microcomputer performs diagnostic functions separately, then diagnostic coverage is complete, but memory capacity requirements increase
Solution Approach 1:
The patent merges the diagnostic data structures of both CPUs into a shared memory layout. Both CPUs use the same diagnostic program storage area and result storage area in their respective memories, allowing them to share the same diagnostic code and comparison logic. This merging approach reduces the total memory capacity required while maintaining complete diagnostic coverage for both CPUs.
Solution Approach 2:
The diagnostic program and its associated data structures are designed to be universal, serving both CPUs simultaneously. The same diagnostic routine and memory structures are used by both microcomputers, eliminating the need for duplicate diagnostic code and reducing overall memory requirements while ensuring both CPUs receive comprehensive diagnostic coverage.
3Measurement precision
If diagnostic results are compared between microcomputers, then error detection accuracy improves, but system complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where each CPU's diagnostic results are fed back to the other CPU for comparison. This inter-CPU feedback loop allows errors to be detected with high accuracy by identifying discrepancies between the two independent diagnostic executions. The feedback is achieved through simple result exchange and comparison operations that add minimal system complexity.
Solution Approach 2:
Each CPU creates a copy of its diagnostic results in memory, and these copies are then compared between the two CPUs. This copying approach enables accurate error detection by allowing direct comparison of identical diagnostic data structures without requiring complex real-time synchronization mechanisms, thereby maintaining relatively simple system architecture.
Data Source
AI summary
The controlling apparatus for an industrial product of this disclosure has a couple of microcomputers each of which has a CPU and a memory and each of which runs the same controlling program as well as the same diagnostic program sequence parallelly and simultaneously. After the CPU of the microcomputer writes the calculated result of the diagnostic program sequence in the predetermined area of the storing area for monitoring value, such CPU send the same calculated result to the other one of the microcomputers (receiving microcomputer). The CPU of the receiving microcomputer makes a diagnosis for finding whether or not the received result is identical with its own calculated result.