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On the relation between software development and control function development in automotive embedded systems

On the relation between software development and control function development in automotive embedded systems . Stefan Kowalewski Embedded Software Laboratory (Chair Informatik 11) RWTH Aachen University. ARTIST Workshop “Beyond AUTOSAR”, Innsbruck, 23-25 March 2006. Introduction.

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On the relation between software development and control function development in automotive embedded systems

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  1. On the relation between software development and control function development in automotive embedded systems Stefan Kowalewski Embedded Software Laboratory(Chair Informatik 11) RWTH Aachen University ARTIST Workshop “Beyond AUTOSAR”, Innsbruck, 23-25 March 2006

  2. Introduction • Observation: Software and control function development currently not smoothly integrated. • Technical issues • Missing bridge between software and control design models and tools • “Soft” issues • Different culture, traditions • Misapprehensions about roles in the development process • Some even think software and control function design are the same. • Model-based Design approaches will require a better integration of both disciplines • Aim of the talk : • Share experiences • Discuss approaches to improve integration

  3. Outline • Background • Experiences • Desiderata • Approaches • Conclusions

  4. Background (1) • Short bio – 2000 Control engineering, Universities Karlsruhe/Dortmund 2000 – 2003 R&D Robert Bosch GmbH, software technology 2003 – Computer science, RWTH Aachen University • My background when entering industry: • Control theory, control engineering • Discrete event systems, hybrid systems theory • Formal verification (model checking) • Main work topics: • Software engineering • Software architecture design and analysis • Software re-use, variability management • Safety and reliability of software-intensive systems

  5. Background (2) • Much higher interest in “soft” topics (company-wide, also by management) • Most pressing (cost) problems have been caused by software development issues (requirements, variability, re-use, etc.), not by control function development • Automotive supplier industry is well experienced in developing new functionality up to prototype and first customer level. • Problems start when additional customers with different requirements must be served and software qualities become important. • “Hard” methods were not in the focus • Control design is considered as being mastered • Formal verification was not of interest

  6. Background (3): Architecture Analysis Workshops • One of the main tools at that time to cope with software issues • Idea: • Software quality is mostly determined by architecture • Analyse early whether the SW architecture supports business-relevant quality requirements • Basis: “Architecture Trade-Off Analysis Method” (ATAM), Software Engineering Institute, Pittsburgh • Workshop format • Participants: Marketing, Architects, Developers, Testers, Evaluators, if possible Management • Steps: Identifying and refining business goals, brainstorming scenarios, play scenarios in architecture, identify critical points

  7. Outline • Background • Experiences • Desiderata • Approaches • Conclusions

  8. Experiences from architecture analyses in business units • Requirements management • Changes of architecture-relevant requirements late in projects • Communication between marketing and development • Business goals unknown to architects • Organizational structures do not fit any more • Domain-crossing functionalities • Re-use, handling variability of products • 1500 variants of gasoline engine control systems sold per year • Re-use concepts did not fit market requirements

  9. Experiences from architecture analyses in business units (2) • No cost models for software • No lifecycle cost considerations • Product prices determined by hardware • Hardware was fixed before software development began • Permanent misunderstandings between control and software engineers

  10. Experiences: Relation between control and SW engineers SoftwareEngineers RequirementsAnalysis Acceptance Test ControlEngineers ArchitectureDesign Integration Test Module/AlgorithmDesign Module Test Handing overprintouts of ASCETor SIMULINK designs Implemen-tation

  11. How control and SW engineers see each other • Control engineers: • System structure (trivial) and algorithms (difficult)follow from control requirements  should be designed by control engineers • Remaining task for software engineers: implementationAs a consequence: responsibility for software quality • Software engineers: • Control engineers already botch it up in the architecture • System structure has to follow from „non-functional requirements“  should be designed by software engineers • Architecture design is challenging, algorithm design is trivial • Computer-aided control design tools (incl. autocoding) are used to avoid software engineering considerations

  12. Outline • Background • Experiences • Desiderata • Approaches • Conclusions

  13. Desiderata • Better understanding between software and control engineers • At least: Sensitivity for different challenges • Methodologically: • Early consideration of software requirements in control design • Early integration of control requirements into software requirements

  14. Outline • Background • Experiences • Desiderata • Approaches • Conclusions

  15. First step: Clarification of goals and responsibilities • For control engineers: • There is more to the quality of control software than correct functionality and good control loop performance. • For software engineers: • Control function design at its core is not a software design problem. • Closed loop dynamics are a challenge of ist own. • Helpful for creating better understanding by control engineers: Strict separation between non-functional and functional requirements or properties  Teaching?

  16. Clarification: Two requirements analysis paths technically oriented business oriented requirements analysis requirements elicitation functional reqs(first version) non-functional requirements(first version) analysis of functional reqs analysis ofqualities functional specification drivingqualities architecturedesign

  17. Clarification: Design viewed as an optimization problem requirements analysis analysis of functional reqs analysis ofqualities functional spec= optimizationconstraints driving qualities= optimizationcriteria design= optimization Find best or good enough solution (measured by qualities) among all admissible solutions (given by functional spec.)

  18. Example for preparing software engineers:Course „Dynamic Systems for CS students“ • Signals • mappings from time to value, no matter whether domain and co-domain are discrete, continuous or hybrid • Systems • mappings from input signal space to output signal space • State as a general concept for representing dynamics automata, cont. state space, hybrid systems • Linear systems • Analysis • General properties: Causality, controllability, observability, reachability, stability • Continuous systems: Frequency domain analysis, time domain analysis • Discrete systems: Temporal logic, model checking • Hybrid systems: reachability • Simulation (integration of ODEs, DES simulation) • Design • Continuous systems: Linear controller design • Discrete systems: Supervisory control synthesis, game theoretic methods

  19. Research: ZAMOMO-Project • Integration of model-based software and model-based control system design • Partners: • Embedded Software Laboratory, RWTH Aachen • Control Engineering Institute, RWTH Aachen • VEMAC GmbH • AVL GmbH • Fraunhofer-Institute for Information Technology • Started this year

  20. Vision of ZAMOMO: Integrated model-based development Early consideration of non-functional requirements in control system design Early introduction ofplant models Requirements Model ? Consistency of models on different refinement levels, automatic transformation possible? Specification Model ? Simulation Model Plant model HiL Model Plant model refined Implementation Plant

  21. Outline • Background • Experiences • Desiderata • Approaches • Conclusions

  22. Conclusions • Challenge: Bridging the gap between software and control development • Technical issues: • Connecting software models and tools with control design models and tools • Soft issues: • Clearer reference model for roles of software and control designers in the development process • Preparation for the cooperation of both disciplines by appropriate teaching

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