System Models to Assess the Impact of Change The IEE Railway System Modelling Not Just for Fun Semin

1
System Models to Assess the Impact of ChangeThe
IEE Railway System Modelling Not Just for Fun
SeminarThursday 30th September 2004Clive
RobertsLecturer in Railway SystemsUniversity of
Birminghamc.roberts.20_at_bham.ac.ukwww.eee.bham.ac
.uk/robertc
2
Background

• Rail Vehicle and Track System Integration Project
  is funded through the EPSRC Systems Integration
  Initiative
• A 3-year collaborative industry/academia research
  project (ending January 2005)
• Research split between University of Birmingham
  and Manchester Metropolitan University
• Multi-disciplinary team Civil Engineers, Vehicle
  Dynamicists, Software Engineers, Metallurgists,
  Electrical Engineers

3
Project Motivation

• Many problems span several engineering
  disciplines and can only be effectively tackled
  by understanding the system as a whole
• Systems engineering together with conceptual
  systems modelling allows problems to be
  investigated more effectively
• In particular the rail industry needs a means of
  investigating the effects of changes on the whole
  system, not just within individual subsystems or
  components

4
Systems Engineering Process
5
Project Work Packages

• Requirements Elicitation to understand what is
  required
• System Modelling to map the relationships and
  interconnections between components
• Compositional Modelling to build new models
  from model fragments and infer knowledge
• TOOLS Database to provide details of existing
  task specific tools and the links between them
• Decision Support System

6
Requirements Elicitation

• Initial part of the Systems Engineering process
• Decomposition of the problem in order to further
  understanding
• Identify stakeholder and system level
  requirements
• Requirements modelling
• Understanding existing practices (cost modelling,
  wear modelling....)

7
Scenarios

• Physical System Relationships

8
Scenarios

• Model Identification (identification)
• To provide the user with models/tools that may
  aid with a particular problem

9
Scenarios

• Model Identification (data flow)
• To provide a series of models/tools which when
  joined together may solve a particular problem

10
Scenarios

• Document Database
• To provide the user with information relating to
  all aspects of a particular component / process

11
Scenarios

• Expert Identification
• Provide details of experts in a particular field

12
System Modelling

• Forms the foundations of the decision support
  system knowledge base
• Hierarchical relationship model to show simple
  interactions between physical components
  (elements)
• Model elicited from domain experts
• Provides a means of communicating about the
  domain under consideration

13
System Modelling
14
System Modelling
15
Compositional Model

• The core of the decision support system engine
• Builds on the simple foundation of the
  hierarchical system relationship model
• Captures the systemic knowledge in an organised
  way
• System knowledge is represented in logical sets
• Software algorithms are linked to model fragments
  in order to compose a scenario model for a given
  scenario

16
Compositional Model
17
Compositional Modelling Terminology

• Decision Variables - elements that change the
  model depending on the decision that is made by
  the user
• Physical Properties- properties that relate to
  the physical arrangement of the model element
• Dependent Variables - elements that are only
  relevant when some interaction occurs in the
  relationship. They can form limiting parameters
  for behaviour i.e. if XgtY then Z.

18
(No Transcript)
19
TOOLS Database
Tools used in the Railway System
Vehicle
Substructure
Management
Infrastructure
W R Interaction
V - I Interaction
Rail
Wheel
Environment
20
VAMPIRE
Introduction
Description
Inputs
Outputs
Contact
Comments
VAMPIRE Vehicle Dynamics Simulation Package
21
Tools
Inputs/Outputs
Inputs/Outputs
Rail Plan
RCF
22
Tools
Inputs/Outputs
Inputs/Outputs
Rail Plan
RCF
23
Decision Support System

• A decision support system to aid railway
  stakeholders to make decisions regarding system
  changes is being developed
• At the core of the DSS sits a hierarchical system
  relationship model which is used to compose
  models for a given scenario
• The user interface will be able to answer
  questions such as
• What affect does x have on y
• What affect does changing x have ......

24
Decision Support System
25
Conclusions and Further Work

• The project aims to generate a reasoned framework
  based on Systems Engineering Models and
  Principles to help railway engineers identify the
  affects of changes on the railway systems
• A prototype decision support system is being
  developed incorporating system modelling,
  composition modelling and the tools database
• Further work will be undertaken in a follow-on
  project to build economics into the models