Specifying the behaviour of building automation systems


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Building automation systems have known an upsurge of interesting due to their energy savings potential and for creating smart environments. However the development of this type of systems consists essentially of embedded systems in hardware controllers written in low level languages which are difficult to program.

In situations where the actuation must vary continually based on the sensor inputs, development and testing becomes even harder. This work proposes a framework based on a declarative language to specify the behaviour of a building automation system. This language allows the specification of the behaviour without worrying about hardware details. This language and framework proposed herein use the notions of fuzzy logic and temporal logic. The specifications developed using the proposed language describe fuzzy control systems that interface with actuators through a different defuzzification process.

We validate our proposal by developing a simulator of the language semantics and animating a case study specification of the control system of an automated office room. For further validation we used sensor reading traces and observed the behaviour of our animated specification, analysing graphic representations of the actuators along the simulation.

Keywords: Building Automation Systems , Behaviour Specification , Fuzzy Logic , Fuzzy Control Systems , Fuzzy Contexts , Temporal Logic , Context-Aware Systems , Expert Systems

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Specifying the behaviour of building automation systems

  1. 1. Specifying the Behaviour ofBuilding Automation Systems João Aguiam September 6th, 2011
  2. 2. Agenda• Motivation• Problem• Our Proposal• Validation• Conclusions 2
  3. 3. Agenda• Motivation• Problem• Our Proposal• Validation• Conclusions 3
  4. 4. MotivationThe smart office example Work DeskDoor Curtains Window Support Table Luminosity Sensor Luminaries Motion Sensor 4
  5. 5. MotivationThe smart office example• Maximize energy efficiency• Control the curtains and luminaries automatically to: • Reduce the amount of artificial light • Allow the maximum amount of natural light inside • Avoid the excessive glare in the working place of the user • Turn lights off if no one is in the office • Adjust light level according to user’s task and place 5
  6. 6. Agenda• Motivation• Problem• Our Proposal• Validation• Conclusions 6
  7. 7. ProblemHow it is done nowadays?• Crafting behaviour into hardware devices (embedded C programs) • Difficult to develop • Lengthy process • Too far away from the problem domain of BA• Hardware modules with pre-packaged applications • Difficult to configure • Sometimes it is impossible to create the desired behaviour due to limited expressivity
  8. 8. ProblemStatement• How to specify, in an easy way, the logic behind the behaviour of a Building Automation System where the actuators output vary continuously based on sensors input? 8
  9. 9. ProblemFuzzy controller • Difficult to specify • Require great expertise • Far from the domain level 9
  10. 10. Agenda• Motivation• Problem• Our Proposal• Validation• Conclusions 10
  11. 11. Our Proposal Logical level Execution level 11
  12. 12. Our ProposalRelation with fuzzy controllers Rule-base Fuzzification Inference Defuzzification Logical level Execution level 12
  13. 13. Our Proposal Context description language• Declarative language based on fuzzy logic and temporal logic• The degree of truth of a context is defined recursively on the value of sensors and other contexts• Some operators reason over a path of past values of sensor readings and contexts 13
  14. 14. Our ProposalScenario description• Scenarios are a set of rules which take the form: if antecedent then consequent• The antecedent is is a fuzzy condition defined using fuzzy contexts and fuzzy context operators• The consequent is an assignment to an actuator which uses fuzzy consequent operator• The assignment to an actuator varies with the truth value of the fuzzy condition• The defuzification process is a simple weighted average 14
  15. 15. Agenda• Motivation• Problem• Our Proposal• Validation• Conclusions 15
  16. 16. ValidationIdeal setting IDE IDE Behaviour Specification Compiler HW UserBA Expert IDE 16
  17. 17. ValidationStrategy1. Illustrative Case Study2. Excel Model3. Interactive Simulator4. Batch Simulator 17
  18. 18. ValidationResults and Discussion Curtains along the day Arriving and leaving Passage of a cloud in the sky Working at desk Working at table Walking around 18
  19. 19. Agenda• Motivation• Problem• Our Proposal• Validation• Conclusions 19
  20. 20. Conclusions• We have created an high level declarative language to specify the behaviour of building automation systems • Adapted the notion of fuzzy context from Ambient Intelligence • Created a well defined syntax and semantics that can be compiled and interpreted • Introduced the notion of time from the temporal logic with a new fuzzy Until operator • Adapted the deffuzification process to a less computational one• We have validated the idea through diverse simulators to test the functionality in different scenarios 20
  21. 21. ConclusionsFuture work• Learning user preferences• Implementing real world simulation• Create an interpreted development environment• Extend the language expressivity 21
  22. 22. Thank You João AguiamSeptember 6th, 2011
  23. 23. Reserve Slides
  24. 24. Context-aware Systems• Adapts to the surrounding environment• Environment is abstracted through the notion of context• CAS gathers information related to context and reasons about it to take a certain action• Context is any information that characterizes the situation and is relevant for the interaction between the user and the system 24
  25. 25. Fuzzy Logic• Propositions may be partially true or partially false and can be seen as fuzzy sets• Fuzzy Sets are represented by a Membership Function (MF)• In Fuzzy Logic the operation conjunction and disjunction are calculated through the operator min and max respectively 1 ColdPlace HotPlace 0.8 Membership Degree 0.6 MildPlace 0.4 0.2 0 0 5 10 15 20 25 30 35 X = Temperature 25
  26. 26. Fuzzy Logic• Fuzzy logic systems are based on fuzzy rules• Fuzzy control systems must result in a single crisp value to control an object 26
  27. 27. Temporal Logic• Propositions are qualified in terms of time• Allows the reasoning in a sequence of events along the time• Most common operators: • Next • Eventually • Always • Until • Releases 27
  28. 28. Expert Systems• Computer program that simulates the reasoning of a human expert to solve problems or give advices to the user• Four topics: • Knowledge acquisition • Knowledge representation • Reasoning control • Solution explanation 28
  29. 29. Fuzzy Context Operator• Defined in the universe of discourse of a context• Allow a customized evaluation of a context• The input of a fuzzy context operator is a context C and its output a value between 0 and 1• Defined by a membership function• Examples are: No, Little, Some, Enough, Much, Too Much and Full. 29
  30. 30. Fuzzy Context OperatorExamples 30
  31. 31. Fuzzy Consequent Operator• Defined in the universe of discourse of an actuator• It is specific for a certain type of actuator• Used in the assignments 31
  32. 32. Fuzzy Consequent OperatorExamples 32
  33. 33. Defuzzification 33
  34. 34. Mandani Fuzzy Inference System 34
  35. 35. Sugeno Fuzzy Model 35
  36. 36. Tsukamoto Fuzzy Model 36
  37. 37. Curtains Along the Day Closed Opened Hours 37
  38. 38. Arriving and Leaving On Off Time 38
  39. 39. Passage of a Cloud in the Sky Time 39
  40. 40. Working at Desk Time 40
  41. 41. Working at Table Time 41
  42. 42. Walking Around Time 42
  43. 43. Limitations• Single user model• Absolute values in the actuator assignments• Set actuators to past values• Reasoning about time intervals• Lack of customization for different users• Validation • Single case study • Scalability • The lack of validation in a real environment 43