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A Spectrum of IV&V Modeling Techniques

Explore the analysis, testing, visualization, prototyping, and code development techniques in model-based development. Discuss the challenges and potential solutions for improving the efficiency and scalability of formal analysis in critical systems development.

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A Spectrum of IV&V Modeling Techniques

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  1. A Spectrum of IV&V Modeling Techniques Mats Heimdahl (Co-PI) Jimin Gao (RA) University of Minnesota Tim Menzies (Co-PI) David Owen (RA) West Virginia University/NASA IV&V Sanjai Rayadurgam (RA) University of Minnesota—Today’s Speaker

  2. Analysis Testing Visualization Prototyping Code Model-Based Development Specification Model

  3. ROI with Model Based Development Source: Esterel Technologies - 37.5 % - 25 % - 75 % - 50 %

  4. Model-Based DevelopmentComing to projects everywhere—soon • Model based development in some form will in the near future be the norm in critical systems development • Airbus Industries require the use of model based techniques from all vendors • Boeing currently evaluating what to require—not if they will require something • Honeywell and Rockwell Collins are fielding the capabilities within the next two years • Etc., etc.

  5. Commercial Products Esterel Studio and SCADE Studio from Esterel Technologies Rhapsody from I-Logix Rose Real-Time from Rational Simulink and Stateflow from Mathworks Inc. Model-Based Development Tools

  6. NASA tools STANLEY/LIVINGSTONE for Integrated (or Intelligent) Vehicle Health Maintenance (IVMS) for second-generation shuttle. Model-Based Tools-2

  7. RSML-e and Nimbus Project with Rockwell Collins Inc. Java Simulations of environment RSML-e Formal Models (~20 running concurrently) • Integration in MatLab • Test case generation • Model checking • Theorem proving

  8. Typical Requirements IV&V Process Initial Assessment Using Low-Cost Approach Formal Inspection Formal Analysis Inspection Automation Inspection Inspection Formal Model of SUS System Under Study (typically English) Formal Model of SUS Formal Model of SUS Model Extraction

  9. Formal Analysis Formal Analysis Inspection Test Inspection Test Model-Based IV&V Process Increased Effort and Cost Model v.1 Model v.n Model v.2 Model v.n-1 Model Evolution Model Evolution Model Evolution Test Code

  10. Challenges in the New Process • Scalability and cost of the formal analysis • State space explosion problems in model checking • Cost effective model evolution • Process and guidelines for evolving the model • Early and cost effective problem detection Formal Analysis Formal Analysis Inspection Inspection Test Test Model v.1 Model v.n Model v.2 Model v.n-1 Model Evolution Model Evolution Model Evolution Test Code

  11. Model checking is plagued by state space explosion problems Are there alternative, possibly heuristic, approaches that are effective? Alternate representations NAYO: a no-and-yes-or graph Hypothesis: NAYOs can be used to evaluate models Express interesting properties Find interesting problems NAYO-based evaluation scale NAYO can be used across the model evolution cycle Work with David Owen, WVU Scalable Analysis

  12. Q: NAYOs can be used to evaluate models? A: Yes!! (using a novel stochastic search engine- ISSRE02) Q: Does NAYO-based evaluation scale? A1: Stochastic search linear time! A2: NAYO stochastic search always plateau! A3: False negative rate falls to zero in the plateau Work with David Owen, WVU Some Results

  13. If the stochastic search does not find problems, are there none? Compare the stochastic results with full verification on realistic models Experiments using: RSML-e Nimbus SMV Stochastic search Flight guidance models from Rockwell Collins How to perform model evolution? Large case study with Rockwell Collins RSML-e suitable for the full spectrum of models Does finding problem in early models indicate a problem system? Does elimination of problems early reduce problems in subsequent models (even if substantially different)? Very difficult to assess No experiment this year Planning for controlled experiment Open Issues

  14. Work with Jimin Gao, U of Minnesota Analysis Experiment RSML-e Spec. • Available Resources: • 6 RSML-e models of Flight Guidance System from Rockwell Collins Inc. • Collection of desirable properties • Translator from RSML-e to • SMV • FSM suitable for stochastic search • Experimental Method: • Seed errors in the FGS models • Apply stochastic search as well as full formal verification • Compare performance and detection capability AutomaticTranslation AutomaticTranslation NAYO Graph SMV Spec.

  15. Model based development is here Or, will be here shortly Great potential to improve quality and decrease cost of IV&V Must meet some crucial challenges first Scalability of formal analysis In particular, state space exploration—model checking Evolution of models Stochastic state space exploration may hold the key But, we need to explore The fault detection capability of stochastic search The efficiency of stochastic search Rigorous experiments are starting as I speak We will also evaluate alternative analysis tools SAL from SRI Summary

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