The%20Team

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(No Transcript)
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The Team

• Clara Cardoso (Acoustical Engineering)
• Ian Farmer (Electronic Engineering)
• Sam Hopper (Electronic Engineering)
• Julian Seidenberg (Software Engineering)

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Project Goals

• To build an online virtual laboratory for control
  systems demonstrations with 3D illustrations of
  the Simulink models
• To develop this system as a cross-platform
  successor to existing tools such as the Matlab VR
  Toolbox 2.0

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Presentation outline

• System Architecture
• Simulink models
• System timing and control wrapper
• Java Client/Server system
• 3D VRML illustrations
• Integration and testing
• Conclusions
• Questions
• Demonstration

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System Architecture

• System-Level View
• Task breakdown

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Architecture Overview
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Architecture Detail
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Advantages

• Platform independence
• Scalability Load Balancing
• Redundancy Recoverability

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Disadvantages

• Complexity
• More complex than a simple single host-to-host
  network connection
• More effort to install and configure
• Performance
• Layer of indirection causes slight delay

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Task Breakdown
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Simulink Models

• Bouncing Ball model
• Radar Tracking
• Pendulum
• F14 Flight Control
• Newtons Cradle

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Bouncing ball model

• Simple system
• Adapted from Matlab demo model
• Expanded to move three-dimensionally

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Radar tracking

• Matlab demonstration model
• Drop in model
• Undocumented

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Pendulum

• Simple pendulum model
• Rotation not translation

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F14 flight control

• Matlab demonstration model
• Models elevator control
• M-file control of variables

Elevator
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F14 flight control (2)

• Adaptation of controller

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Newtons cradle

• One pendulum model per sphere
• Connected via collision modelling blocks
• Pendulum velocity can be set on collision

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System Timing and Control Wrapper

• Controls the timing of the control system
  simulation
• Interfaces the simulation with the server

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System Timing

• Data sent from Simulink
• in fixed-length packets
• at fixed intervals
• Display applet requires a regular data stream
• Therefore the accuracy of the timing is important
  for a smooth simulation

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Timing Development

• First timing test
• Used a fixed pause between packets
• Caused a gradual time lag

• Second timing test
• Used absolute timing from system clock
• Sufficient accuracy is achieved

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Development of Control Wrapper

• Implementation of a dataflow delay using an
  s-function block
• Delay block can halt the execution of the
  simulation at regular intervals

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Final Timing and Control Wrapper

• Implemented as a two-block wrapper for a control
  system model
• Datasource providing the control systems inputs
  from the server
• Datasink regulating the execution speed and
  sending the control systems outputs to the server

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Java Client/Server System

• Technology choices
• System topology
• Matlab/Java Interface
• Process View (Server)
• Java Control Applet

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Technology choices

• Java 1.1
• not
• PHP
• ColdFusion
• C/C
• C
• Matlab

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Technology choices (2)

• IBM Java Classbroker
• not
• Java RMI
• XML-RPC
• SOAP

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Matlab/Java Interface
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Process View
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Java Control Applet
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3D Worlds

• Why?
• To create illustrations of the control systems
• To appeal to users
• Building
• Combining and scaling
• Created objects
• Existing objects on the web
• Modified downloaded objects

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Software Used
Software For What? Why?
VRML 97 To develop the worlds Free, easy, available plug-in-less browser, already used in VR-Toolbox, many downloadable objects
Blaxxun 3D VRML Viewer Free, plug-in-less, small file size
3D Exploration File Converter Converted many different file formats, fast, identification of objects parts
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Software Used (2)
Software For What? Why?
Blender Object creation and modification Free, cross-platform many online resources and tutorials
MilkShape 3D Object creation and modification Imports and exports many file formats, easy to use and learn
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Bouncing Ball

• Ball inside a box controlled by Simulink
• Used to learn and become familiar with VRML
• Grass texture in the ground and a textured
  hemisphere sky
• Airplane propellers and windmill sails rotate

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Radar World

• Radar to track an airplane
• The phantom airplane shows the radar tracking
• Normal airplane shows what the radar should
  track
• Radar created in Blender
• Camera tracking the planes so that the user is
  able to follow them whilst they fly around in the
  world.

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F14 World

• F14 flying
• Camera tracking the plane so that the user is
  able to follow it while flying around in the
  world.

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Newtons Cradle

• User to interact with a Newtons cradle
• Newtons cradle developed in Blender
• House made from rectangular planes
• Window is a rectangular plane with its
  transparency material property set to a low value

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Pendulum

• A pendulum swinging represented by a pendulum
  clock
• Room with old fashioned objects
• Pendulum needed to function as a different group
  to the rest of the object modelled using
  MilkShape3D

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Integration and Testing

• System Integration
• Summary of Testing

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System Integration

• Control System models ? 3D Worlds
• Synchronising objects and nodes from the model to
  the world
• Ensuring correct positioning and visualisation
• Control System Models ? Interface Wrapper
• Incorporating the final model as a sub-system in
  the interface wrapper
• Interface Wrapper ? Server
• Using instances of Java objects to connect and
  transfer data to and from the server
• Server ? Client
• Finalising networking code in order to let
  multiple clients connect to multiple servers

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Summary of Testing

• Simulation timing and execution test results
• Performance is dependent on the power of the host
  computer
• Increased sample times need more processing power
• Java client/server system test results
• Works without major failures under most
  conditions
• However, re-declaration of variables caused
  stability problems over extended periods of
  operation until fixed.

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Summary of Testing

• Other areas tested
• Performance/load testing
• Fail-over Testing
• Cross platform compatibility
• Areas not tested
• Usability testing
• Security testing

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Summary

• Evaluation
• Conclusions
• Future Work

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Evaluation
GDP VRC VR-Toolbox 2.0 Viewpoint LabView
Download size 141 KB VRML 5470 KB VRML 3200 KB Wavelet compressed file 200 MB
Installation necessary No Yes Yes Yes
Simultaneous users Thousands Unspecified Thousands 50
Bandwidth requirement Modem LAN Modem LAN
Platform independent Yes (Java) No (Windows only) Somewhat (Windows Macintosh) Somewhat (Windows Linux)
Quality of image Medium Quality High Quality Very High Quality N/A
Accuracy of simulation Good Good N/A Very Good
Price Free 1870 Free 3345
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Conclusions

• Platform independence by the use of a three-tier
  system and the Java technology
• Privacy Security isolation of Matlab and Java
  applet clients from each other through the server
  was achieved.
• Scalability Load Balancing The system
  continued to run with a load of 3000
  simultaneously connected clients.
• Analysability Testability It is relatively
  simple to create client applicants to analyse and
  test the system.
• Maintenance Flexibility Good maintainability.
  Encapsulation in objected-oriented programming
  ensures the system is flexible.

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Conclusions (2)

• Stability Recoverability The system is
  resistant to clients crashing. Recovery occurs
  quickly enough in normal use.
• Small size quick download Average download
  time of just over a minute for a dial-up user and
  seven seconds for a broadband user
• Ease of use The web pages are intuitive.
• Performance Adequate performance on an
  up-to-date computer.
• Accuracy Accurate as possible with todays
  technology.

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Conclusions (3)

• The system can be used by clients with a broad
  range of skill levels
• simple
• accessible
• diverse selection of examples
• Potential application areas
• virtual teaching laboratories
• advertisement on the University web page
• worldwide conferences.

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Future Work

• Improving security
• Improving analysability
• Improving display smoothness
• Introducing dynamic data stream buffering
• Creating an automatic installation system
• Creating a system that solely uses Matlab and is
  not reliant on Simulink
• Increasing the amount of control a user has over
  Matlab
• Increasing the amount of information provided on
  the web pages.
• Providing cut down versions of the VRML models
  for slow Internet connections
• Providing a three-dimensional object library

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Demonstrations