Cyber-Physical Systems:
Issues and Challenges
Rabi N. MahapatraTexas A&M University
(Adopted from NSF Workshops)
April 18, 2023 1WECON 2011
April 18, 2023 WECON 2011 2
Overview
What are Cyber-Physical Systems? Emerging Context: Applications,
technical & Economic Issues & Challenges Application Specific Research
Identification Summary
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What are Cyber-Physical Systems?
What are CPS?– Are they desktop computers?– Are these traditional, post-hoc embedded/real-time systems?– Are these today’s sensor nets?
Ans: None of the above!
• Some defining characteristics:– Cyber capability in every physical component– Networked at multiple and extreme scales– Complex at multiple temporal and spatial scales– Dynamically reorganizing/reconfiguring– High degrees of automation, control loops must close at all
scales– Unconventional computational and physical substrates (Bio?
Nano?)– Operation must be dependable, certified in some cases
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Economic Context: US & EU Competitiveness American Competitiveness Initiative announced:http://www.whitehouse.gov/stateoftheunion/2006/aci/
EU Framework Programme 7, European Research Council, and related actions
• ARTEMIS– Backbone of European Research Area for Embedded Systems,http://www.artemis-office.org/• Strategic Research Agenda (SRA)• Joint Technology Initiative (JTI)• Embedded systems education and curriculum– “High-Level Group”• CEOs: ABB, Airbus, Nokia, Parades, British Telecom, COMAU, Philips,Bosch, Continental Teves, Daimler/Chrysler, ST Microelectronics,Symbian, Ericsson, Finmecanicca, Telenor, Thales, IMEC, Infineon• Universities and national research labs: TU Vienna, CNRS/Verimag– Joint public and private funding
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Example: Health Care and Medicine National Health Information Network, Electronic Patient Record
initiative– Medical records at any point of service– Hospital, ICU, …, EMT?• Home care: monitoring and control– Pulse oximeters (oxygen saturation), blood glucosemonitors, infusion pumps (insulin), accelerometers(falling, immobility), wearable networks (gaitanalysis), …• Operating Room of the Future (Goldman)– Closed loop monitoring and control; multipletreatment stations, plug and play devices; roboticmicrosurgery (remotely guided?)– System coordination challenge• Progress in bioinformatics: gene, proteinexpression; systems biology; disease dynamics,control mechanisms
Images thanks to Dr. Julian Goldman, Dr. Fred Pearce
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Example: Electric Power Grid
Current picture:– Equipment protection devices triplocally, reactively– Cascading failure: August (US/Canada)and October (Europe), 2003
Better future?– Real-time cooperative control ofprotection devices– Ubiquitous green technologies– Issue: standard operational control concerns exhibit wide-
area characteristics (bulk power stability and quality, flow control, fault isolation)
– Context: market (timing?) behavior, power routing transactions, regulation
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Example of a CPS concept (fiction)
Weebo – from the movie ‘Flubber’Concept : Personal Assistant
Flubber © Disney Motion Pictures 1997
Application Example
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Fiction becomes reality
NASA – Personal Satellite Assistant (concept)
•Will help astronauts in space
•Will have built-in propulsion and navigation
•Can go to difficult to reach places
Personal Satellite Assistant © NASA Ames Research Center
Application Example
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Personal Satellite Assistant
•The PSA is about the size of a softball
•Has sensors for measuring gases, temperature, and air pressure.
•PSA can video conference & communicate with electronic support devices such as computer servers, avionics systems, and wireless LAN bridges.
•PSA is a robotic assistant for astronauts working in space.
Artist’s concept of a PSA assisting an astronaut
Images © NASA Ames Research Center
Prototype
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Defining Cyber-Physical Systems:
A cyber-physical system integrates computing, communication and storage capabilities with the monitoring and/or control of entities in the physical world dependably, safely, securely, efficiently
and in real-time.
Seek scientific foundations and technologies to integrate cyber-concepts with the dynamics of
physical and engineered systems.
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Long-Term Goal
Transform how we interact with the physical world just like the internet transformed how we interact with one another. Transcend space and yet control the
physical environment
Produce significant impact on society and national competitiveness.
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Industry Sectors To Benefit
Automobiles Industrial Automation Energy Defense and Space Intelligent Homes and Health/Medical Equipment
Other Sectors to benefit:• Telecommunications• Consumer Electronics
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Possible Cyber-Physical Systems
Medical devices and health management networks Tele-physical operations Vehicular networks and smart highways Physical infrastructure monitoring and control Electricity generation and distribution Robotic manufacturing Aviation and airspace management Defense and aerospace systems …
In general, any “X by wire(less)” where X is anything that is physical in nature.
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Fundamental Challenges
From a synthesis perspective Architecture Requirements and their management Formalization of the constraints imposed
by the Physical layer (physical – cyber interface and boundary)
Grand Challenge:Compositional approach to Cyber-Physical
Systems Design and Synthesis.
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From IT Abstractions to “Hardware/Software”
From DNA‘programs’ toliving organisms
From CAD schematics to chips
ISR-SEIL, Copyright © 2006
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From IT Abstractions to “HW/SW”
No difference between HW and SWHW/SW co-design,, software radios
ISR-SEIL, Copyright © 2006
From algorithms and schematics to radios
Embedded systems design tools
Picoradio
R-50 Hovering
INS
GPS Antenna
GPS Card
UAV Controller
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A Glimpse into the Future Autonomic wireless networks, self-organizing collaborative robotics,
self assembled systems and materials Computing over new Physical domains
(Quantum, organic, biological) •from abacus to qubits• entanglement• nuclear spin, electron spin• photon polarization, ion trap
As dimensions getsmaller what is cyberand what is physicalgets fuzzier
From material layercontrolled by cyber layer
to “programmable matter”
True convergence ofControl, communicationcomputing
•Communicating minds
•Swarm intelligence
ISR-SEIL, Copyright © 2006
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Areas of Challenge
Communication between the components
Data Storage & Retrieval Data Security Scalability Management of the CPS devices User Interfaces Safety
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Communication
Large amounts of data transfer will be required
Will need enhanced wireless protocols which support Low power consumption
(can power criteria be part of the protocol ? ) High Bandwidth High Data Transfer Rates Intelligent traffic management and
routing.
Image © davisdrive.wcpss.net
Challenge > Communication
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Will require robust security to protect the data that is to be transferred.
Should be light on computational and memory requirements.
Should be able to gracefully degrade in case of attacks.
Can we have self-quarantining of compromised sections/areas ?
Communication-SecurityChallenge > Communication
NSF Workshop, Austin, October 17, 2006
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Data Storage & Retrieval
Depending on application Monitoring type application
low quantity on individual nodes Interactive application
possibly huge amounts of data stored
Should adopt distributed storage algorithms
Algorithm selection cannot be generic, will be application specific.
Image © NeoScale Systems Inc
Challenge > Data Storage & Retrieval
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Scalability
CPS will be a global, open & extensible platform
Questions: How do we describe, discuss, deduce the
invariants of such a global system ? How do we model the expansion of such
a system ? How will such a system scale to
planet-wide use and deployment ?
Challenge > Scalability
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Management of CPS
How do we deploy and control large scale applications ? Wireless networks that can perform self-
organization. Adaptive routing protocols for traffic
control and efficient routing. Multiple smaller deployments that
collaborate into one large network . (an Internet of CPS ?)
Image © www.niaid.nih.gov
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Interactive Complexity Two dimensions− Coupling: Tight vs. Loose• Delay and ordering tolerance,resource slack,inherent buffering (vs. designed in)− Interactions: Complex vs. Linear• Degree of feedback, number of common modeconnections, limited system understanding, relianceof human expertise, many control parameters Systems with high interactive complexitypossess numerous hidden interactionsthat can lead to systems accidents− Nuclear Power Plants− Chemical Plants− Software Systems System Accident: The halting of systemoperations due to damage or failure ofmultiple subsystems that arises from theunanticipated interactions of multiplefailures
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Cyber Physical System Accidents
USS Yorktown(http://www.slothmud.org/~hayward/mic_humor/nt_navy.html )
− Suffered a systems failure when bad data was fed into itscomputers during maneuvers off the coast of Cape Charles,VA.− The ship had to be towed into the Naval base at Norfolk,VA., because a database overflow caused its propulsionsystem to fail− ”We are putting equipment in the engine room that wecannot maintain and, when it fails, results in a criticalfailure," DiGiorgio said. It took two days of pier-sidemaintenance to fix the problem.
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Accident due to SW Bug
Ariane Five(http://www.ima.umn.edu/~arnold/disasters/ariane5rep.html)
Ariane 5 reused a module developed for Ariane 4, which assumed that the horizontal velocity component would not overflow a 16-bit variable.− This was true for Ariane 4 but not for Ariane 5, leading to self-destruction roughly 40 seconds after the launch.− “The [Ariane 5] alignment function is operative for 50 seconds after starting of the Flight … This time sequence is based on a requirement of Ariane 4 and is not required for Ariane 5.” (Report by the Inquiry Board)
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Interactive Complexity in Cyber Physical Systems Cyber Physical Systems Typically Have High Interactive Complexity− Many tightly coupled system threads with hard deadlines− Shared resources among mission critical and non-mission critical systems− Give rise to numerous hidden dependencies, which then lead to unexpectedfunction, performance, or accidents Limited Design Time Support to Understand or Reduce Interactive
Complexity− Existing analytical methods e.g. rate monotonic analysis, address individualaspects but skilled practitioners are required to employ these techniques• As a result we see limited application− Simulations are typical hand written and are difficult to keep synchronizedwith the design; or abstract away details that lead to hidden dependencies Present Cyber Physical Systems Rely on Human Ingenuity at Design Time
and Extensive System Testing to Manage Interactive Complexity− As a result, we experience long and costly development efforts that are expected to
encounter system accidents.
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Application Specific Approaches
Cyber-Bio Interface
Critical Physical Infrastructure
Tele-Interaction
Smart Transportation
System Infrastructure
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Cyber Bio Interface
The four questions for cyber-bio systems
1. Can biological systems operationalize certain aspects of cyber systems so that we can understand and design advanced biological systems?
2. Can biological systems operationalize certain aspects of cyber systems so that we can understand and design advanced cyber systems?
3. Can cyber systems operationalize certain aspects of biological systems so that we can understand and design advanced biological systems?
4. Can cyber systems operationalize certain aspects of biological systems so that we can understand and design advanced cyber systems?
Application Specific Approaches
Harvey Rubin, MD, PhD University of Pennsylvania, NSF, Austin, October 17, 2006
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Cyber Bio Interface
1. Can biological systems operationalize certain aspects of cyber systems so that we can understand and design advanced biological systems?
Answer : YES
Up to the level of tissues and cultures, this is predominantly in the world of synthetic biology.
1918 Flu Epidemic : Complete genome sequenced in 2005
Application Specific Approaches
Harvey Rubin, MD, PhD University of Pennsylvania, NSF, Austin, October 17, 2006
April 18, 2023 WECON 2011 34
2. Can biological systems operationalize certain aspects of cyber systems so that we can understand and design advanced cyber systems?
Answer : No
While DNA computation has been proved possible, time for the ‘gate’ to operate has been in the order of several seconds
Cyber Bio InterfaceApplication Specific Approaches
Harvey Rubin, MD, PhD University of Pennsylvania, NSF, Austin, October 17, 2006
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Cyber Bio Interface
Physical Limitations of DNA Computing Hamiltonian path problem
25 nodes….. 1 kilogram of DNA needed
70 nodes….. 1000 kilograms of DNA needed !
Application Specific Approaches
Harvey Rubin, MD, PhD University of Pennsylvania, NSF, Austin, October 17, 2006
April 18, 2023 WECON 2011 36
Cyber Bio Interface
3. Can cyber systems operationalize certain aspects of biological systems so that we can understand and design advanced biological systems?
Answer: Yes
Nano-bio Medical devices Lab on a chip NSF workshop on high confidence
medical devices and software systems last year
Subject of Tele-Physical services and applications working group at NSF Workshop
> $3 billion invested already !
2007 NSTI Nanotechnology Conference and Trade Show – May 2007 - Santa Clara
Application Specific Approaches
Harvey Rubin, MD, PhD, University of Pennsylvania, NSF, Austin, October 17, 2006
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Cyber Bio Interface
4. Can cyber systems operationalize certain aspects of biological systems so that we can understand and design advanced cyber systems?
Answer : Yes !
Has been happening all the time:
Application Specific Approaches
Harvey Rubin, MD, PhD, University of Pennsylvania, NSF, Austin, October 17, 2006
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Cyber Bio Interface
examples abound (from molecular level to societal level) Persistence in bacteria
hedge strategy against attack Cellular metabolism : metabolic flux models
supply chain Swarm behavior
Autonomous mobile robots Inverse problem
Markets Data aggregation Event prediction
Application Specific Approaches
Harvey Rubin, MD, PhD, University of Pennsylvania, NSF, Austin, October 17, 2006
April 18, 2023 WECON 2011 39
Critical Physical Infrastructure
What is Critical Physical Infrastructure? CPS Infrastructure: Interconnected
systems with seamless interaction between computing and physical systems.
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Critical Physical Infrastructure Current Challenges What to do with data collected by the CPS - for e.g.
(oil pipeline inspections) Translate / Interpret data and arrive at a decision Communicate with the people in charge.
Develop large scale models of the physical world Being done in SCADA for prediction SCADA - Supervisory Control And Data Acquisition :
(called Human Machine Interface in Europe) Large Scale Distributed Measurement (and Control) System
We need data on abnormal conditions CPS are subject to massive (cascading) failures. Power Grid, Air Traffic, Automotive, Data Centers
How do we handle unpredictable component interactions ?
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Tele-Interaction
Remote/Distributed = Tele Perception Action Interaction
NSF Workshop, Austin, October 17, 2006
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Scenarios Tele-Interaction Application First responder applications
Dangerous environments, under water exploration, fire fighting
Tele-health, tele-services for aging population (assisted living) Collaborative dancing Physiotherapy between a doctor and patient
Training environment for training medical personal for tele-surgery Tele-immersion inside of the body
Network of robots and sensors that work in a cyber-physical spaces with a remote human in the loop to accomplish dangerous, unpleasant, or super-human activities
Factory automation and reconfiguration
NSF Workshop, Austin, October 17, 2006
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Tele Interaction - Unmet Needs Latency-sensitive Internet Display technology and the overall I/O
technology Haptic technology needs higher time
resolution, many sensors and display to emulate whole hand sensing and actuation
Interactive human-machine interfaces are limited
Managing Complexity Networked self-organization Trust, Security and self-certifying software
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Tele-Interaction Challenges
How do we achieve being in remote space feeling in remote space effecting remote space
Synchronization in multi-modal environments; Trust (reliability, safety, privacy, …) Robust and fault tolerant systems Achievement of autonomy and semi-autonomy Reusable user interfaces
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Smart Transportation Challenges
Basic Goal : move people and goods Safely and reliably Efficiently (min resources, no environmental
damage) Quickly Desirably (passenger’s experience should be fun)
“Smart” ? Use CPS to improve / facilitate all of the above Use the transportation system to provide traffic,
GIS, terrain data
NSF Workshop, Austin, October 17, 2006
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CPS Enabled Automobile Trend
Goals– Enhance safety of vehicle and occupants during various driving
maneuvers; avoid crashes– Enhance convenience of driver of the vehicle• Trend is shift from warning-only or information-only systems (e.g.,collision warning systems) to systems that actively control accelerationand braking (longitudinal motion) and steering (lateral motion), leading
to semi-autonomous and eventually fully autonomous vehicle operation
• Examples:– Forward collision warning– Adaptive Cruise Control (ACC) + extensions – Curve speed control– Side blind zone alert– Lane change assist– Lane keeping / lane centering control– Cross traffic collision avoidance– Parking assist
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Research Needs for Auto Industries
360°sensing via vision, radar, sonar, and sensor fusion for higher levelsituational awareness• Robust requirements: how should the vehicle behave in anticipation ofevery possible real-world driving scenario
• Driver experience, skill level, and mental state (e.g., drowsiness, inattentiveness)
• Vehicle state of health / maintenance / repair• External environmental factors (weather conditions, road conditions,
traffic conditions)• Learning, adaptable, reconfigurable run-time systems
• Fault tolerant architectures– Hardware and Software fault tolerance (USCAR project on run-time
architecture)• Distributed diagnosis/prognosis• Human Vehicle Interface– Sensing and learning the driver’s skills, habits, and current condition
(attention, drowsiness, impairment)– Driver workload management
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System Infrastructure
Problem Statement: Coupling interface between computers
and the physical world. Methods and models for validation Co-development
Self Configurability of systems and system parameters within requirements
Self description capable , self aware systems Education
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System Infrastructure -Challenges
Dealing with time, distributed architecture, space, scale
Dealing with the hybrid nature of CPS Security ?
Adaptive OS / Self regeneration capability
Engineering Education Issues
NSF Workshop, Austin, October 17, 2006
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Summary
CPS is the hype of next decades! Involves multi-disciplinary research
High confidence SW CPS has the potential to change the
way people interact with their surroundings
applications in the future for CPS are limited only by human imagination
Affordability and ease of use will drive adoption
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