Fidelity Requirements Specification

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Fidelity Requirements Specification

• A Process Oriented View

Manfred Roza Delft University of Technology
Aerospace Control Simulation Delft, The
Netherlands
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Contents

• Introduction
• Fidelity and Requirements Engineering
• FiReS Basic Concepts
• FiReS Fidelity in the FEDEP Model
• FiReS Major Process Activities
• Conclusions and Future Research

99 Fall Simulation Interoperability Workshop
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Introduction

• What are Fidelity Requirements?
• FDM-ISG Fidelity Definition A Measure of
  Realism
• Fidelity Requirements A Formal Description of
  the Level of Realism a Model or Simulation Must
  Display in order to Fulfill its Intended Purpose
  Properly
• Why Do We Need Fidelity Requirements?
• Era of All You Can Afford Fidelity is Passé
• Fidelity as a Possible Tool for Validation
• What is Needed?
• Formal Specification Process and Format
• Integration with the FEDEP and Related Overlays

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Classes of Requirements

• Functional Requirements
• Desired Services or Functions a System Must Offer
  to Satisfy the Users Needs
• Prime Service of a Simulation Representation of
  Some Part and Aspects of the Real World
• Non-Functional Requirements
• External Constraint the System Must Fulfill
• Performance, Available Resources, Quality
  Attributes.
• Limit the Achievable Fidelity of a Simulation

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Requirements EngineeringProcess Model
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FDM-ISG Fidelity Concepts
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Basic Elements of FidelityRequirements
Specifications

• Two Level Approach
• Level One Simulation Fidelity Requirements
• Map Simulation Purpose to a Description of
  Required Real-World Aspects
• Level Two Simulation Component Fidelity
  Requirements
• Translate Simulation Fidelity Requirements to an
  Internal Realization
• Recommended Elements
• Fidelity Referent and Other Sources
• Required Real-World Aspects Detail, Resolution
  and Capacity
• Behavioral Representational Characteristics
  Error Tolerance
• Timing Approach (Non) Real-Time, Event Driven,
  etc.
• Fidelity Metrics and Measurement Methods

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FiReS and the FEDEP Model
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FiReS Federation ObjectivesCapturing True
Needs and Objectives

• Desires and Needs
• Desire What the user thinks what is required to
  solve the problem
• Need Formal statement of the users desires
• True Needs Essential Desires
• Wishes Non Essential Desires
• Simulation Objectives
• State what the simulation is to establish to
  satisfy the users needs
• Set of Abstract Functional Requirements
• A First Scenario and Coarse Indication of Fidelity

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FiReS Activities in Federation Objectives
Development

• Get the Right People Involved
• Elicit Problems and Needs
• Use Top-Down Approach for Elicitation
• Retrieve Information from Preliminary Studies
• Analyze Problems and Needs
• Identify Application Domain and Simulation Type
• Distil Core Problem and True Needs
• Organize True Needs in a Prioritized List
• Negotiate the Problem Need Statement

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FiReS Activities in Federation Objectives
Development

• Elicit Non-Functional Requirements
• Develop Federation Objectives
• Selection of Suitable Fidelity Referent and
  Standards
• Use Fidelity Referent for Initial Fidelity
  Requirements
• Consult (Fidelity) Requirements of Similar
  Federations
• Feasibility Analysis and Validation
• Use Non-Functional Requirements and True Needs
  List for Making Fidelity Trade-Off Decisions
• Inspection Review Sessions with Users and SMEs

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FiReS Conceptual ModelingCapturing Federation
Fidelity Requirements

• Conceptual Modeling
• What Constitutes a Conceptual Model?
• No Formal Structure or Development Approach
• Suggested Elements Algorithms, Architecture,
  Available Data, Assumption,.
• Mapping of Objectives to a Set of Detailed
  Functional Simulation Requirements
• FiReS versus Conceptual Modeling
• Both Identify Required Aspects of Reality
• A Two-Way Complementary Relationship

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FiReS Activities in Conceptual Model Development

• Develop Scenario
• Refine Initial Scenario in terms of Resolution
• Determine Federation Capacity
• Address Environmental and Geographical Fidelity
• Perform Conceptual Analysis
• Develop Detailed Fidelity Requirements
• Refine Federation Resolution in Top-Down Fashion
• Add Tolerances for Behavioral and
  Representational Properties
• Add the Conditions for which the Tolerances
  Should Hold
• Determine Suitable Timing Approach

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FiReS Activities in Conceptual Model Development

• Perform Conceptual Analysis (Cont.)
• Federation Fidelity Specification
• Internal Realization Algorithm Selection
• Error Interaction and Propagation Precision
  Sensitivity
• Initial Federation Architecture Ideal FOM SOMs
• Develop Federation Requirements
• Specify Fidelity Requirements in Formal Format
• Add Fidelity Measurement Methods to the Fidelity
  Requirements Specification
• Validation of the Fidelity Requirements
  Specification

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Conclusions and Future Research

• Fidelity Requirements and Specification Process
  are Essential
• FEDEP not Consistent with FDM-ISG Framework and
  Concepts
• Current FDM-ISG Concepts Work for FiReS but Need
  Further Improvement
• Future Refinement of the FiReS Method
• Detailed Formal Fidelity Specification Format
• Fidelity Requirements Validation Issues
• Practical Application of FiReS

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Thats All Folks
Any Questions?