Bestavros, Azer

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Boston University Institutional Repository (OpenBU)

Boston UniversityOpenBU http://open.bu.eduBU Open Access Articles BU Open Access Articles2008-05-08Cyber-physical systems: challenges& opportunitiesThis work was made openly accessible by BU Faculty. Please share how this access benefits you.Your story matters.VersionCitation (published version): A Bestavros. 2008. "Cyber-Physical Systems: Challenges &Opportunities." Sensor Network Consortium, May 8, 2008.https://hdl.handle.net/2144/26108Boston University1http://www.cs.bu.edu/groups/wingCyber-Physical SystemsChallenges & OpportunitiesAzer BestavrosComputer Science DepartmentBoston UniversitySensor Network ConsortiumMay 8, 2008 May 8, 2008 CPS @ SNC 2Cyber-Physical Systems (CPS)Cyber PhysicalSystemMay 8, 2008 CPS @ SNC 3CPS: Major Roadblock? All our software frameworks abstract out or add uncertainty to spatio-temporal attributes:? Programming languages? Virtual memory? Caches? Dynamic dispatch? Speculative execution? Power management (voltage scaling)? Memory management (garbage collection)? Just-in-time (JIT) compilation? Multitasking (threads and processes)? Component technologies (OO design)? Networking (TCP)? …May 8, 2008 CPS @ SNC 4CPS: Certification is key? By definition, CPS = Safety Critical ? System must be certified with respect to a variety of stringent safety constraints? Safety constraints? Real-time constraints? Non-interference constraints? Fail-safe constraints? Not about proofs of concept? Cost is a secondary concern!May 8, 2008 CPS @ SNC 5The Hospital Dilemma? Paraphrasing John Rushby, SRI  “The patient on the operating table is the medium through which multiple life-support (respiratory and circulatory) subsystems interact. There are documented cases of deaths and severe injury due to medical device interference.”? Who is liable? The manufacturers? The hospital? A real stumbling block for innovation!May 8, 2008 CPS @ SNC 6The Boeing Dilemma? Paraphrasing Edward Lee, UC Berkeley: “In fly by wire aircraft, it is not the software that is certified but the entire system. If a manufacturer expects to produce a plane for 50 years, it needs a 50-year stockpile of fly-by-wire components that are all made from the same mask set on the same production line. Even a slight improvement require the software to be re-certified.”? What about outsourcing? How is Airbus doing it?2May 8, 2008 CPS @ SNC 7What Could Go Wrong??A few potent examples? Interference between controllers? Interference between multiple life support subsystems? Compatibility questions? Will upgrading break my system? (regression is hell!)? Data plane interactions? Could I substitute a Kalman filter with another?? Control plane interactions? Do firewall security rules compose safely with my network monitoring infrastructure? May 8, 2008 CPS @ SNC 8What Could Go Wrong??A few potent examples? Interference between controllers? Interference between multiple life support subsystems? Compatibility questions? Will upgrading break my system? (regression is hell!)? Data plane interactions? Could I substitute a Kalman filter with another?? Control plane interactions? Do firewall security rules compose safely with my network monitoring infrastructure? SCALEMay 8, 2008 CPS @ SNC 9(Scalable) Compositional Analysis? Composition:The system Z that results from having X interact with Y? Analysis:Formally derive safety properties of a system W? Analyzing a composition:Derive properties of Z by analyzing the composition of X and Y? Composing the analysis:Derive properties of Z by composing the analysis of X and the analysis of YMay 8, 2008 CPS @ SNC 10Component Property Projections ? Allows us to abstract the system for a particular perspective? But, for CPS, no one perspective is enough! May 8, 2008 CPS @ SNC 11Need to “Compose” Theories? Different techniques are better at dealing with different types of properties? Thermodynamics: Heat diffusion; energy transfer, …? Control theory: Convergence, stability, dynamics, …? Network calculus: Max/min delays, b/w, loss rates, …? Queuing theory: Average delay, utilization, ? Real-time theory: Schedulability/timing analysis, QoS, …? State-space analysis: Deadlocks, synchronization, …? Game theory: Price of anarchy, mistreatment, …? … put your pet theory here? Need a seamless way to leverage all such theories and techniques May 8, 2008 CPS @ SNC 12BU Project: snBenchDesign/implement an integrated software development and certification environment for CPS applications over a shared CP infrastructureThis is as easy as Java! The CPS is the computer…Cyber PhysicalSystem3May 8, 2008 CPS @ SNC 13snBench: Hourglass Model…? If the Physical World is the Computer, then what is its ISA?? Why an ISA?? Minimizes cost? Encourages innovation? Speeds up adoption? Scales up educationMay 8, 2008 CPS @ SNC 14… One Hourglass Model / Theory May 8, 2008 CPS @ SNC 15snBench: Goals? Write once; run anywhere? Don’t program nodes; program the CPS!? Start with building blocks – “Gadgets”? Models of the physical domain objects ? Sensors (cameras, motion sensors, biosensors, …)? Actuators (device controllers, net services, …)? Stock algs (Kalman filter, FFT, edge detect, …)? Glue together with high-level language? Conditionals, loops, triggers, functions? Pretend the network isn’t there? “Single CPS System Image”? Integrate programming and verificationMay 8, 2008 CPS @ SNC 16snBench: Programming Cycle? Program? Program specified by gluing together building blocks using a high-level language (SNAFU)? Compile and Certify? Program is compiled to produce a plan of execution expressed over a CPS domain abstraction (STEP)? Map and Link? STEP plans are decomposed in smaller dispatch-able STEPs which are linked ? Load and Execute? STEP plans are dispatched and loaded onto the computational core of the CPS infrastructureMay 8, 2008 CPS @ SNC 17snBench: Certification? Annotations used to define behavioral constraints, a.k.a., “types”? Annotations are distilled into domain-specific formal representation of the interfaces between CPS “gadgets”? Use type-checking and type inference to mechanically verify safety properties a prioriMay 8, 2008 CPS @ SNC 18snBench: RoadmapCertified STEP ProgramSRM: SensoriumResource ManagerCPI ApplicationThe SensoriumCyber-PhysicalInfrastructureType Casting & TransformationsType Safe?SNAFU Compilation ServicesYesNoVerification ErrorSES: Sensorium Embedding ServicesTRAFFIC Formal SpecificationSTEP Program RepresentationBound STEP ProgramSSD: SensoriumService DispatcherSchedulable?YesNoExecuting STEP Programemail(“security@bu.edu”, trigger((motion(snapshot(cam2)) && (2am<NOW<4am)),snapshot(cam2))) Type Inference & DebuggingDebugging ReportInsufficient Resources Error4May 8, 2008 CPS @ SNC 19snBench: Status? Used as a platform for projects in SE and AI courses in CS since 2005!? Students developed opcodes, GUIs, resource managers, applications, rule-based front-end for medical devices, …? Multimodal sensing and actuation using motes, PTZ-cams, kismet wireless intrusion detection, Garcia robots, …? snBench is Alive!? Latest code and demos from multiple case studies at http://csr.bu.edu/snbench/May 8, 2008 CPS @ SNC 20CPS: ChallengesFrom executive summary of CPS Summit Report, April 2008May 8, 2008 CPS @ SNC 21CPS: StakeholdersMay 8, 2008 CPS @ SNC 22CPS: A Global R&D Priority? Federal Networking and Information Technology R&DFormative planning workshops by HCSS coordinating group? The CSTB and the National AcademiesSufficient Evidence? Building Certifiably Dependable Systems? Forthcoming significant R&D fundingNSF started a seeding program in 2007? Computing Research AssociationA focus area of the Computing Community Consortium? Convergence of RT, SN, Emsoft, Hybrid and ControlFirst CPS Summit with co-located events held in late April ? Beyond academia and beyond the USSCADA, Automotive, MD PnP, Aviation, EU ARTEMIS & EPoSSMay 8, 2008 CPS @ SNC 23How Could SNC Members Help?? CPS research is domain-specific? We need domain experts for the modeling and control of physical (mechanical, electromagnetic, biological, chemical, biophysical, biochemical, medical, …) phenomena? We need test-beds and opportunities for student training? What is your CPS application? http://www.cs.bu.edu/groups/wingCyber-Physical SystemsChallenges & OpportunitiesAzer BestavrosComputer Science DepartmentBoston UniversitySensor Network ConsortiumMay 8, 2008

Cyber-physical systems: challenges & opportunities

https://open.bu.edu/bitstream/2144/26108/1/CPSoverview.pdf

Cyber-physical systems: challenges & opportunities

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