An Introduction to Cyber-Physical Systems INF5910/INF9910

Transcription

1 An Introduction to Cyber-Physical Systems INF5910/INF9910 1

2 Outline What is Cyber Physical Systems (CPS)? Applications Challenges Cyber Physical CPS 2

3 Cyber Systems Cyber is More than just software More than just networking More than just embedded computing Computation Cyber implies the integration of Computation, Communication Control 3

4 Physical Systems Physical natural and human-made systems governed by the laws of physics and operating in continuous time Highway Power Airline Factory 4

5 What are Cyber-Physical Systems? Cyber-Physical Systems systems in which the cyber and physical systems are tightly integrated at all scales and levels CPS Integrates computation and physical processes uses embedded computers and networks to compute, communicate, and control the physical processes receives feedbacks on how physical processes affect computations and vice versa. Computation Information Systems 5

6 A CPS Architecture Vincenzo Liberatore, Networked Cyber Physical Systems: An Introduction,

7 Start from an example: Cooling Data Center In 2010, data center uses 3% of total USA energy budget Cooling equipment uses at least 50% total energy cost. A key challenge is to minimize the cooling requirement, toward optimizing the operations of data center 7

8 Cooling data center: Cyber-physical approach Observation: Some locations in data center are easier to cool than others A B Solution: moving tasks from Zone A to Zone B lower overall power consumption Temperature distribution in data center R.K.Sharma etal. Balance of Power: Dynamic Thermal Management of Internet Data Centers. Jan.2005 CPS Approach: distribute tasks among the servers to minimize the temperature cyber coupled physical 8

9 CPS characteristics Cyber capability in every physical component Networked Sensing technology Pervasive networking Predictable behavior Real time operation & close loop control High confidence software & systems Cyber and physical components are integrated for: learning and adaptation, higher performance, self organization, self assembly 9

10 Outline What is cyber physical systems? Applications Challenges 10

11 CPS applications 11

12 Power Grid/Smart Grid Current picture: Power outage over the world 25 July 2010, Washington D.C., people lost power 22 March 2010, Malta, nationwide blackout Better future? Real-time protection Buildings are more energy efficient to operate 12

13 Car-to-Car Communications Safety: vehicles allow their neighbors to track them and predict possible collisions Traffic information: share information on the traffic on-road for traffic congestion alarm 13

14 Outline What is cyber physical systems? Applications Challenges 14

15 A New Area Artificial intelligence Can machines think? By A. Turing in Computing Machinery and Intelligence, 1950 Ubiquitous Computing Computers everywhere By Mark Weiser, XEROX PARC, 1990 Pervasive Computing 6As Model, The authorized access to anytime anywhere any device any network any data Industry vision (1999, IBM, etc.) Cyber Physical Systems Computation and networking integrated with physical processes 15

16 Challenges Build the interface between the cyber world and the physical world? Why this is hard: No clear boundaries between cyber and physical worlds. Boundaries are always changing. No perfect digitization of the continuous world Inpredicable complex systems Essentially multi-disciplinary 16

17 Multi-disciplinary Sensing technologies Distribute computing and networking Real-time computing Control theory Signal processing Embedded systems This seminar will cover some areas, focus on both introductory and latest topics related to CPS and its sub-areas. 17

18 Introduction to Wireless Sensor Networks 18

19 Outline What is Wireless Sensor Networks (WSN)? Applications challenges 19

20 Sensor nodes 20

21 Sensor node model Low-power processor Limited processing. Memory Limited storage Mobility No or limited movement Communication Low-power. Low data rate. Limited range. Sensors Scalar sensors: temperature, light, etc. Cameras, microphones. Power Storage Real World Sensor Unit CPU Communication Powered by battery with long-time operation in unattended areas P O W E R 21

22 What are Wireless Sensor Networks (WSNs)? Networks of typically small, battery-powered, wireless devices. On-board processing, Communication Sensing R A B 1-hop neighborhood R: transmission range V: the set of sensor nodes Sensor node Wireless Sensor Network 22

23 Outline What is Wireless Sensor Networks (WSN)? Applications Research challenges 23

24 City Sensing Use WSN to measure city pollutants Carbon monoxide (CO) Put sensors on taxi When the taxi are moving around in a city, the sensors on the taxi can sense the air quality 24

25 Engineering, civilian, enterprise applications will eventually dominate WSN in building environment WSN is deployed at the Golden Gate Bridge to monitor structural health Golden Gate Bridge San Francisco Structural vibrations are measured and collected by sensors 25

26 Forest observation, fire detection In a forest, collecting data including temperature, humidity, and CO2 etc. Applications, e.g. forest surveillance, forestry observation, fire risk 26

27 Volcano monitoring Monitor active and hazardous volcanoes 27

28 Military Operation: Shooter localization WSN determines the shooter location Red circle: the estimated shooter position Red line: the shot direction Green dots: sensor locations. Idea: using the arrival times of the acoustic events at different sensor locations, the shooter position can be accurately calculated using the speed of sound and the location of the sensors.

29 Oceanic Environment British Petroleum oil spill at the Gulf of Mexico and its huge environment damage in 2010 monitor the environmental conditions of the ocean surface 29

30 Wildlife behavior analysis and Put a camera (i.e. video sensor) on each deer. interaction modeling The captured video will be transmitted to a remote monitoring center for real-time viewing, control; wildlife behavior analysis 30

31 Medical Monitoring, e.g. heart rate, blood pressure WSN can be on/beside/in body Remote monitoring for aged people at home; patient at hospital 31

32 Outline What is Wireless Sensor Networks (WSN)? Applications challenges 32

33 Challenges Severely energy constrained. Limited energy sources (e.g., batteries). Trade-off between performance and lifetime. Resource-constrained systems Power Computation Bandwidth Scalable. potentially large number of nodes 33

34 Lifetime in WSN Objective: how to maximize the lifetime of whole network Lifetime definition the time until the first sensor is drained of its energy Tn n =min v 2 V T v T n n: network lifetime; T v : the lifetime of node v the time until all nodes have been drained of their energy Tn n =max v 2 V T v 34

35 Various Issues Energy models, energy efficiency Routing/packet forwarding Medium access control Localization Data fusion Clustering Topology control Security Novel applications QoS Delay, throughput, packet delivery ratio, packet error rate Real-time transmission in body sensor networks, wireless video sensor networks 35

36 Routing in Wireless Sensor Networks Source node A B Sensor node C Objective: choose multi-hop routing path from source node A to the sink Constraints: Energy efficiency QoS (delay, packet delivery ratio) D Sink node Wireless Sensor Network 36

37 Medium Access Control in WSN Role: coordinate access to and transmission over a medium common to all nodes. Challenge: Interference, Limited energy, Limited bandwidth, Fading channel, Decentralized Causes for energy consumption Packet collision, overhead, idle listening 37

38 Localization in WSN Objective: determine a node s position Challenges: Limited communication range All the measurements are inaccurate because of multi-path fading. Interferences Node mobility Applications Tracking patient, old people, children who need help in case 38

39 Social networks [1/3] We are witnessing an explosion of social Networks, websites, apps, tools. Facebook users has more than 1/9 of world population It is social world: of the 10 most popular web sites, 5 represent social networks 39

40 Mobile Social Networks[2/3] Not just using mobile phone to access Facebook MSN 40

41 Mobile Social Networks (MSN) [3/3] MSN: mobile users of similar interests establish network connectivity and communicate with each other Common interest, e.g. basketball, StarCraft, travel, music Properties: mobile users usually move around well-visited locations Regular user s dwell time at each community Challenges: Social-aware information sharing and dissemination 41

42 Smart Grid Communications: Conventional Power Grid [1/3] Power is generated in a plant Power is distributed through the long-distance highvoltage transmission networks to the local community Power is distributed to the customers The communications is one-way, i.e., from utility to customers

43 Smart Grid Communications: Two-way information flow [2/3] Provide two-way communication between customers and utilities Traditionally, only one-way communication from utility to customers To improve Efficiency Sustainability Security Stability

44 Smart Grid Communications: Challenges [3/3] High volume of generated data: over TB by SBI Research reports Intensive radio environment: The spectrum is becoming dramatically crowded ZigBee, Bluetooth, WiFi, and more Domestic appliance (e.g., microwave ovens) Interoperability: the grid architecture is a heterogeneous multi-tiered topology Different energy sources usage Green wind, solar traditional power utility

45 Current machine-to-human or human-to-human communication soon transits to M2M communications [1/2] machine-to-human human-to-human Machine-to-machine (M2M ) : no human intervention whilst devices are communicating end-to-end.

46 Machine-to-Machine ( M2M) Communications: characteristics [2/2] low-power, low-cost, and low human intervention typically composed of a very large number of networked devices Several constraints: energy, computation, storage, and bandwidth etc.