Model-based Development

1. Model-based Development By Ryan Mowry

2. Modeling Basics • Graphical models of system • Entire system or just parts • Complex systems easier to understand • “Capture key requirements and demonstrate correct behavior in simulation”

3. Software Process • Starts after requirements • Can cover design, development, and testing

4. Design and Analysis • Representation of system • Inputs • Outputs • Mathematical Operations

5. Design and Analysis • Match model to target architecture • Correct data types for input/output • Interactions with other systems

6. Design Example

7. Simulation • Simulate model based on inputs and parameters • Observe actual outputs of the model compared to expected • Allows testing parallel to design

8. Simulation Advantages • Earlier error detection • Easy to test all input ranges • Improve Verification • Able to make changes to the model to reach expected results

9. Model-in-the-Loop Testing • Testing a model using input from another model • Models interact with one another so useful data can be obtained by testing current model with a working existing model • Earlier error detection

10. Software-in-the-Loop Testing • Testing model in conjunction with generated or handwritten code on one machine • Useful when parts of generated code are updated to test compatibility with old code • Also for handwritten code that will be used with generated code

11. Software-in-the-Loop Testing • Test software algorithm using model instead of needing actual hardware

12. Processor-in-the-Loop Testing • Generated code executes on target processor • Test code on target processor with system model using actual I/O (CAN) • One step from hardware testing allows for more error detecting before needing actual expensive hardware

13. Hardware-in-the-Loop Testing • Use generated code for both target architectures to test code functionality • Real-time system simulates actual target device to detect more errors between systems • Last testing before integrated testing

14. PIL and HIL

15. Implementation • Verify model and simulation meet requirements • Auto-Generate code from model • Code and filenames very abstract • Hard to follow and understand

16. Implementation • Code already tested • Changes to model if necessary • Regenerate code from corrected model instead of changing code • Floating and fixed point conversion

17. Is Model-based Development Worthwhile? • High costs in new software • Time and cost to learn the model-based approach • Greater time spent during analysis and design of the system

18. Research in Automotive Industry • Model-based Development became popular among automotive companies • Some companies thought lowered cost, others thought no difference or even higher cost • Global research study by Altran Technologies, chair of software and systems engineering, and the chair of Information Management of the University of Technology in Munich

19. Goals of Research • Cost difference in each software phase • Analysis of amount of modeling used • Error Detection • Cost Difference • Quality Criteria • Overall Cost

20. Software Phase Analysis

21. Requirements Cost Change

22. Number of Errors Detected

23. Quality Criteria

24. Overall Cost

25. Research Study Findings • Modeling helped cut overall costs of the project • Increased quality and bug detection • Less than 60% implementation of model-based development yielded the best results but depends on project

26. Advantages of Model-based • Do not need to know programming languages • Testing sooner leads to earlier bug detection • Better overall quality • Design reuse for upgraded systems

27. Disadvantages of Model-based • New Software costs • Training on new software and approach • Abstract code • Lengthy Simulations • Advantages outweigh disadvantages

28. Simulate, then Design • New methodology in automotive industry • New technologies create major design changes • Simulations help find balance in subsystems • Design comes after balance found through simulating

29. Model-based Embedded Tools • LMS Imagine Lab • Modelica • CyDesign • Dymola • MapleSim • VisSim • MATLAB and Simulink • EicasLab • Rational Rhapsody

30. MATLAB and Simulink • Block diagram of desired system • Diagram hierarchy of components • Useful in sharing components with other models

31. Block Diagram Example

32. Component Hierarchy

33. Running Simulation • Graphical output to view results • Debug Simulation • Step forward to find when state changes • Or step backwards (Rewind Simulation) • Run on target hardware

34. Generating Code • Once model and simulation meet requirements and errors have been fixed, code can be generated for system. • Simulink allows for generating code in C,C++,HDL, and PLC

35. Simulink demo • Demo Simulink Simulation process

36. Sources • Broy, M.; Krcmar, H.; Zimmerman, J.; Kirstan, S.: Model-based Software Development – Its Real Benefit. EETimes, March 2011 • Gegic, G,: In-the-Loop Testing Aids Embedded System Validation. http://www2.electronicproducts.com/In_the_loop_testing_aids_embedded_system_validation-article-FAJH_Mathworks_Jul2009-html.aspx, August 3, 2009 • Ledin, J.; Dickens, M.: Automatic Embedded Code Generation from Simulation Models. RTC Magazine. http://www.rtcmagazine.com/articles/view/100276, December 2004 • Morey, B: ‘Simulate, then Design’ Emerges as New Engineering Methodology. SAE OHE, September 1, 2011 • "Simulink." Simulation and Model-Based Design. N.p., n.d. Web. 24 Oct. 2012. <http://www.mathworks.com/products/simulink/>.