A Formal Requirements Modeling Method Based on HVRM for Safety-Critical Systems

Requirement errors are prevalent, hazardous, and costly in system development. Applying formal methods during the requirement design phase represents a viable strategy for mitigating such errors. This paper proposes a formal modeling approach based on the Hierarchical Variable Relation Model (HVRM) for safety-critical system requirements. We formalize the HVRM framework by defining its core structure and assignment propagation mapping semantics. To address prevalent challenges of informal and inconsistent requirement descriptions in engineering practice, we establish domain-specific constraints for HVRM-compliant requirements. A systematic method is introduced to transform textual requirements into standardized formal representations compatible with VRM models. Finally, we demonstrate the efficacy of this approach through case studies on the Safety Injection System and Flight Guidance System, validating both feasibility and effectiveness.