why what how

The What, Why and How of Functional Modeling: 

The What, Why and How of Functional Modeling Morten Lind Ørsted DTU Automation & Center of Electric Technoloy Technical University of Denmark (mli@oersted.dtu.dk)

Research interests: 

Research interests Conceptual design of I&C systems deriving high level control requirements from process knowledge Intelligent control reasoning about control situations agent systems Decision support reduce human error by designing the HMI to support means-end reasoning in diagnosis and planning tasks

Agenda: 

Agenda What is functional modelling (FM)? Why functional modelling? How to do functional modelling? Multilevel Flow Modelling (MFM) Diagnostic Reasoning with MFM MFM implementations The need for formalization Summary How? Why? What? Formali sation 1980 2005 Historical perspective

What is functional modelling ?: 

What is functional modelling ? Getting started Defining the concept of function Means-end and part-whole relations Framing Physical and social facts Design and use functions The objectivity of functional assignments

Getting started: 

Getting started The function of the pump is to transport water What does this mean? How can we make use of this type of knowledge in HMI and intelligent control? What is functional modelling ?

Some observations: 

Some observations Functional descriptions refer to relationships Functional descriptions can be defined on various levels of specification (transport, transport of water, transport of water by pressure production)

The concept of function: 

The concept of function Given two systems P and Q: The aim of functional modelling is to represent the system P by the functions (roles) it serves in the achievement of goals and purposes of Q (and vice versa) Functions as effects: The functions of P in relation to Q are the effects of its behaviour or structure on Q H. Simon, ”The Sciences of the Artificial”: Functions define P’s interface to Q What is functional modelling ?

Functions and the means-end relation: 

Functions and the means-end relation What is functional modelling ?

Many to many mappings between means and ends: 

Many to many mappings between means and ends What is functional modelling ?

Why, what and how: 

Why, what and how Why the system is there What the system does How the system does it What is functional modelling ?

P and Q may have two interfaces: 

P and Q may have two interfaces What is functional modelling ?

Part-whole and means-end structures are not isomorphic: 

Part-whole and means-end structures are not isomorphic P is part of Q What is functional modelling ? P Q P Q whole part means end means end

Types of purposes: 

Types of purposes to achieve a target state the doing of the action (function) to enable another action (function A purpose of an action (function) could be: What is functional modelling ? Nested means-end structures

Slide14: 

Whay is functional modelling ?

The role of interpretation in modeling: 

The role of interpretation in modeling What is functional modelling ?

Framing: 

Framing To frame is to experience a situation in relation to a particular conceptual setting or viewpoint To reframe is to change the frame within which a situation is experienced and to place it into another frame which fits the ”facts” of the same concrete situation equally well or even better and thereby changes its entire meaning Framing (and reframing) play a crucial role in human problem solving What is functional modelling ?

Three frameworks of interpretation(Goffman and Habermas): 

Three frameworks of interpretation (Goffman and Habermas) What is functional modelling ?

Framing of technical objects: 

Framing of technical objects as a material object (the physical framework) as an object of control actions use-function (the social framework) as a purpose design-function (the social framework) a pump a composite object made of iron and plastic an actuator What is functional modelling ?

Functions are assigned to objects in a context of purpose Functions are observer relative : 

Functions are assigned to objects in a context of purpose Functions are observer relative What is functional modelling ?

Searle’s hierarchy of facts: 

Searle’s hierarchy of facts What is functional modelling ?

Are functional assignments objective?: 

Are functional assignments objective? What is functional modelling ? This is a pump This is a pump This is a good pump

Searle’s ”hierarchy” of facts: 

Searle’s ”hierarchy” of facts What is functional modelling ?

Comparing functional modelling with differential equations: 

Define the modeling problem Levels of abstraction and granularity Determine system purpose and roles and functions of subsystems Use knowledge of physics and chemistry to setup differential equations expressing process dynamics Use the differential equations of the process to design the control algorithm – also expressed in differential equations Background assumptions. Often ignored or assumed ”obvious”. Sometimes expressed informally in textual form What is functional modelling? Comparing functional modelling with differential equations Traditional control engineering approach to modelling:

A simple example: 

A simple example Background assumptions purpose of tank is to receive, store and deliver water the water is a moveable, storable and fluid substance system is located in a gravitiational field so that the water is received by the tank and leave the valve when opened the purpose of the table is to prevent the tank from falling The differential equation What is functional modelling ?

Each term in the differential equation relate to the background assumptions: 

Each term in the differential equation relate to the background assumptions ability to input pipe to deliver water (dependent on gravity) ability of tank to deliver water (dependent on gravity) ability of tank to contain water ability of water to fill a spatial volume causal relation Functional assignments represent background assumptions What is functional modelling ?

Functional assignments and semantic roles: 

Functional assignments and semantic roles ability to tank to contain water (spatial volume) ability of water to fill a spatial volume (density) Function: storage of water ability to be stored (patient) ability to store (agent) What is functional modelling ?

Why functional modeling?: 

Why functional modeling? Coping with system complexity Functional modeling for hmi design Functional modeling for control systems design

System Complexity: 

System Complexity Enumerative complexity: Large number of systems elements and relations Semantic complexity: Many interpretations of the same phenomena Why functional modelling ?

Semantic Complexity: A simple but complex example (Mariottes bottle): 

Semantic Complexity: A simple but complex example (Mariottes bottle) Problems: To distinguish the functions of process and the control Subsystems serve several functions at the same time (multifunctionality) System functions depends on operating goals and conditions (phases) These semantic problems escalate in large scale process plant and biological systems Why functional modelling ?

The relevance of functional modelling for HMI: 

Functional modelling support problem reframing and can therefore be used to identify task dependent information needs Identification of the problem and finding its solution require multiple framings of the fault situation Information needs depends on the task to be solved and the available means of remedial action Why functional modelling ? The relevance of functional modelling for HMI

Functional modeling for hmi design:An example: 

Functional modeling for hmi design: An example A simplified ship cooling system A fault scenario Why functional modelling ?

Slide32: 

Why functional modelling ?

The relevance of functional modelling for control: 

The relevance of functional modelling for control FM support integrated process and control systems design by making high level design opportunities and constraints explicit FM can be used to reason about control strategies, diagnosis and planning problems FM can be used to identify implicit assumptions in control systems designs based on ODE (ordinary differential equations) FM can be used in HMI design to make functions of the control systems transparent to the operator and to develop support for strategic control decisions Why functional modelling ?

Functional modeling in intelligent control: 

Functional modeling in intelligent control By having knowledge about process goals and functions the control system can adapt to major process changes The control system can identify and diagnose plant wide system faults and reason about possible counteractions The control system is able to explain its purpose and thereby make its behaviour more transparent to the operator. Why functional modelling ?

How to do functional modelling: 

How to do functional modelling Multilevel Flow Modelling

Groups working with MFM research: 

Groups working with MFM research Prof. Morten Lind, Ørsted DTU, Technical Universiy of Denmark Prof. Akio Gofuku, Department of Systems Engineering, University of Okayama, Japan Prof. Jan Eric Larsson, Department of Information Technology, Lund University (also President of GoalArt) Also previous activities at Prof. Hidekazu Yoshikawa, University of Kyoto, Japan Prof. Peter Wieringa and R. Van Paassen Delft University of Technology Prof. M. Veloso, Carnegie Mellon University, USA Toshiba, Japan How to do functional modelling ?

Slide37: 

Overview of MFM development history How to do functional modelling ?

Multilevel Flow Modeling (MFM)- an approach to functional modelling: 

Multilevel Flow Modeling (MFM) - an approach to functional modelling Basic principles of MFM Causal roles and control Diagnostic reasoning using MFM Implementations How to do functional modelling ?

Basic principles of MFM: 

Basic principles of MFM MFM is based on means - end and part-whole abstractions How to do functional modelling ?

Slide40: 

Flow functions MFM Flow function concepts and symbols (standard version) How to do functional modelling ?

Slide41: 

MFM relations How to do functional modelling ?

Example: A Central Heating System: 

Example: A Central Heating System How to do functional modelling ?

MFM of the Central Heating System(Goal - Objective View): 

MFM of the Central Heating System (Goal - Objective View) How to do functional modelling ?

MFM represent relations between goals, objectives, functions and components: 

MFM represent relations between goals, objectives, functions and components How to do functional modelling ?

Mediate (M) and producer-product (PP) relations: 

Mediate (M) and producer-product (PP) relations How to do functional modelling ?

The condition (C) relation: 

The condition (C) relation How to do functional modelling ?

MFM of the Central Heating System(Objective - Function - Component View): 

MFM of the Central Heating System (Objective - Function - Component View) How to do functional modelling ?

MFM answer why, what and how questions: 

MFM answer why, what and how questions How to do functional modelling ?

MFM represents the plant as an action system : 

MFM represents the plant as an action system Action aspects: How to do functional modelling ?

MFM based diagnosis and planning – search strategies: 

MFM based diagnosis and planning – search strategies How to do functional modelling ?

Search in Objective-Function structure is reflected as zoom and mooz operations in component structure: 

Search in Objective-Function structure is reflected as zoom and mooz operations in component structure How to do functional modelling ?

Modeling control and safety systems: 

Modeling control and safety systems Causal roles Control functions How to do functional modelling ?

Causal roles : 

Causal roles Example How to do functional modelling ?

Examples: 

Examples How to do functional modelling ?

Control functions: 

Control functions How to do functional modelling ?

Example: 

Example Tank process The tank has two functions St1 (storage) Ba1 (barrier) Tank process with control The control loop has three functions Change causal roles (see tr2) Introduce a new barrier (Ba2) Maintain water level at href How to do functional modelling ?

It is also a function of control systems to generate and maintain new levels of process functions: 

It is also a function of control systems to generate and maintain new levels of process functions The control loop transform The tank process into a flow balance system How to do functional modelling ?

FM in integrated process and control design: 

FM in integrated process and control design MFM models define high level design patterns representing functional constraints between process and control functions The functional constraints represents design constraints How to do functional modelling ?

The needs for formalization: 

The needs for formalization Ensuring completeness and consistency of functional concepts Domain modelling Modeling strategies for framing and reframing i.e. shifts in conceptual setting or viewpoint How to do functional modelling ?

MFM Implementations: 

MFM Implementations MFM and diagnostic strategies has been implemented at Ørsted-DTU in the JAVA based expert system shell JESS (a CLIPS clone). Gofuku’s group has an implementation in JAVA A commercial model builder and reasoning tool has been implemented by the Swedish company GoalArt. GoalArt has been used in several industrial pilot projects for filtering of alarm showers How to do functional modelling ?

MFM workbench: 

MFM workbench How to do functional modelling ?

Sample Rule (Jess rule language): 

Sample Rule (Jess rule language) (defrule create-causal-17 (connection (upstream ?func-up) (downstream ?func-down1)) (connection (upstream ?func-up) (downstream ?func-down2&~?func-down1)) (balance (name ?func-up)) (transport (name ?func-down1) (upstreamrole upstreamagent)) (transport (name ?func-down2)) ?last <- (postdiction (function ?func-down1) (downstream-prop TRUE) (state hiflow) (not-possibly-primary nil)) (test (not-asserted-previously ?last ?func-down2)) => (create-postdiction ?func-down2 loflow TRUE TRUE ?last)) How to do functional modelling ?

Summary: 

Summary MFM represent relations between intentional and causal aspects of complex technical systems An MFM model comprise a multiple of interconnected perspectives of the system MFM can be used to model fault management strategies used by domain experts MFM has been implemented and is under pilot testing in industry