Legacy Medical Device Control Code Testing via Symbolic Simulation
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Solution Overview
Problem
Legacy code in medical technical devices is difficult to test for specification-compliant functionality due to outdated software and hardware structures, leading to unreliable test results and potential safety risks when hardware or software changes are made.
Innovation Solution
A method involving parallel execution of test procedures on original and modified systems, using symbolic simulation and automatic decomposition of software code into sections, with comparison of results to ensure specification-compliant functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If modern software test procedures are applied to legacy code, then software security requirements can be met, but the testing becomes extremely expensive and unreliable due to outdated software and hardware structures
Solution Approach 1:
The patent creates a virtual copy of the legacy system through symbolic simulation, allowing modern test procedures to be executed on this virtual model rather than the actual outdated hardware. This copying approach enables reliable testing while avoiding the constraints and costs of working with the original legacy infrastructure.
Solution Approach 2:
The patent replaces the physical mechanical testing approach (direct execution on legacy hardware) with a symbolic simulation system that uses abstract representations. This substitution allows modern testing methodologies to be applied without being constrained by outdated hardware structures, thereby improving reliability while reducing testing complexity.
2Measurement precision
If unit tests are performed on legacy code, then specification-compliant functionality can be verified, but false-positive results occur due to outdated code structures
Solution Approach 1:
The patent introduces symbolic simulation as an intermediary layer between the test procedures and the legacy code. This intermediary translates modern testing concepts into forms compatible with legacy code structures, allowing accurate verification without generating false positives that would occur with direct testing approaches.
Solution Approach 2:
The patent transforms the testing approach by changing parameters from direct execution on legacy systems to symbolic representation and simulation. This parameter change allows test results to be measured with higher precision while maintaining reliability, as the symbolic model accurately represents the legacy system's behavior without its structural limitations.
3Adaptability or versatility
If hardware components of legacy systems are modified, then system modernization is achieved, but positive field experience becomes invalid and regulatory review is required
Solution Approach 1:
The patent creates a virtual copy of the original legacy system configuration through symbolic simulation, preserving the exact behavior and characteristics of the proven hardware-software combination. This allows modifications to be tested against the virtual copy to ensure equivalence, enabling modernization while maintaining the validity of field experience through formal verification.
Data Source
AI summary
The present disclosure relates to testing software code of a productive system for a medical technical device, such as a dialysis machine or a blood treatment device, when hardware-side and/or software-side changes are made to the productive system. The software code may be legacy code. When operating the productive system with the legacy code, field data is collected that is at least indirectly considered in the test.