System Design I: Functional Decomposition

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System Design IFunctional Decomposition

• At Sony, we assume all products of our
  competitors will have basically the same
  technology, price, performance, and features.
  Design is the one thing that differentiates one
  product from another in the marketplace
• Norio Ohgo, Chairman and CEO, Sony
• Functional decomposition is probably the most
  pervasive design technique used for engineering
  systems
• Functional decomposition follows the
  transformation of inputs to outputs (under
  external control, if present)
• Its a top-down design technique

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Bottom-Up vs. Top-Down Design

• Bottom-up
• The designer starts with basic components and
  synthesizes them to create the overall system
• Consider designing a car from many parts will
  the final product meet requirements?
• Pros Leads to efficient subsystem
• Cons Difficult to meet requirement Complexity
  difficult to manage Difficult redesign
• Top-down
• The designer has an overall vision of what the
  final system must do, and the problem is
  partitioned into components, or subsystems that
  work together to achieve the goal
• Pros Highly predictable design cycle Full
  utilization of requirements Efficient
  development of large systems
• Cons More time spent in planning May limit
  creativity
• In reality, the designer must alternate between
  both designs

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Functional Decomposition

• Top-down design process
• Recursively divide and conquer
• Split a module into several submodules
• Define the input, output, and behavior
• Stop when you reach realizable components
• Decomposition is usually guided by Functional
  Analysis following Requirements Specification
• Functional Analysis
• Identify top level functions (actions/objectives)
  the system must perform
• Functions may ultimately be accomplished through
  the actions of the equipment, software, people
• Specify whats (not hows)
• Iteratively keep decomposing functions onto a
  lower-level functions

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• Functional Flow Block Diagram
• End product of functional decomposition shows
  sequence of system activities
• Incrementally refine and mark inputs / outputs /
  controls
• Used to illustrate system organization and major
  interfaces
• Build at the later stage of Concept Generation
• Sample system functional breakdown - see next
  page
• Functional Allocation
• Combine or group similar functions into logical
  subdivisions, identifying major groups
• Conversion of the whats into hows system
  broken down into components
• Trade-offs studies involved implementation
  approaches involved

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Level-0
System Requirements
Top-level functions
Level-1
Function A
Function B
Function C
Function D
Function E
Function F
Second-level functions
Level-2
E.2
E.4
E.5
E.1
E.3
E.6
E.3
Figure System functional breakdown
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Component 1
Component 2
Component 3
Function A
Function B
Function C
Function D
Component 4
Function E
Function F
Figure Functional allocation
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Levels in Functional Decomposition

• Level 0
• This is where you start the highest level
  involving one block only, i.e. a block
  corresponding to your system
• Define inputs, outputs and system functionality
  (requirements)
• Level 1
• Typically referred as main system architecture
• Architecture means the organization and
  interconnection between modules. Describe the
  operation how modules work together.
• Define functional requirements for each module.
• Level 2
• Typically shows the organization of components
  within a single module

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• Decomposition process continues until you reach
  Detail Design
• This is where the problem can be decomposed no
  further and you identify all available components
• Number of levels can vary your design should
  have Level 0, 1 and 2, at minimum
• Proposal requires to include Level 0 and Level 1
  design
• Design Document requires all levels

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Example Audio Power Amplifier(Chapter 5.4)
Level-0
Level-1
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Example Thermometer Design
Level-0
Level-1
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Project Management

• Motivation
• Engineers are regularly engaged in projects in
  their careers
• Middle management continues to shrink
• Industry now organizes more around projects than
  functions
• Engineers have led the way on project management,
  it is now hot and trendy
• According to a survey 1 required skill for new
  engineers Project Management Skills
• Project Management ? To complete the project
• On-time
• Within budget
• So that it meets the requirements

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Work Breakdown Structure

• WBS is a hierarchical breakdown of the tasks and
  deliverables that need to be completed in order
  to accomplish the project objectives
• ACTIVITY a combination of a task and its
  associated deliverables
• TASK/CHECKPOINT an action that accomplishes a
  job
• DELIVERABLE an entity that is delivered to the
  project
• An ACTIVITY must have (see Table 10.1)
• Definition of the work to be done
• Timeframe for completion of the activity
• Resources needed
• Person(s) responsible for the activity
• Predecessors other activities to be completed
  before
• Checkpoints for monitoring the progress

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Graphical Visualization of the Project

• Network diagram
• Not a perfect method
• See Figure 10.2
• A network of activities and dependencies between
  them

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• Gantt chart
• Preferred method for project visualization
• See Figure 10.3
• Developed by Henry Gantt (1861-1919) a bar
  graph representation of activities on a timeline
• Frequently, each activity must be complemented by
  a numeric Task Completion Rate (in percentages)
• Include Milestones major in-progress demos
  given to your FS

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• Please use the following simplified version of
  Gantt charts

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Guidance for creating WBS

• Build the plan after the design architecture is
  complete
• Take the initial time estimates for activities
  and extend them almost by 50-75
• Assign a lot of time for testing and integration
• Factor in lead times for part ordering
• Do not assign all team members to all tasks
• Track the progress versus the plan
• Dont become a slave to the plan
• Experience counts

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Project Manager

• May have primary responsibility for the project
  WBS and Gantt Chart but team member should help
  by providing an input
• Responsible for monitoring the progress,
  checkpoints and deliverables against the plan
• Responsible for developing strategies to handle
  potential problems (Always have a Plan B !!!)
• Responsible for preparation, quality screening,
  and timely delivery of requested
  documents/deliverables
• PM is not necessarily the boss in the traditional
  sense and should be a member of the team
  contributing to technical tasks as well

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• Should focus his/her energy on motivating and
  integrating the team !!!
• Responsible for scheduling and organizing team
  meetings
• Responsible for calling weekly meetings and other
  if necessary
• Have a meeting agenda in a written hardcopy form
• Distribute the agenda to all members at the
  beginning of each meeting
• Ask for additions to the agenda
• Follow agenda during the meeting
• Keep notes about decisions and assignments
• Agree on the next team meeting
• Right after the meeting
• Write down a list of decisions and assignments
• Distribute it immediately (in the e-form) to the
  team members

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Costs

• For Senior Design class you do not need to
  develop a budget
• But you need to monitor and report your costs
• Parts/material/software cost should not exceed
  600, in general
• You will need to provide cost figures in ECE-493
  Progress Reports - so keep all invoices
• Each team member must record effective manhours
  spent and show them in your ECE-493 reports as
  well

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Managing Your Bank Account

• Each team must set rules to manage the teams
  budget
• In general, follow the following guidance
• Allocate one person to be responsible for funds
  and purchases (different than Project Manager)
• This person must
• Keep all invoices and cash buys data
• Provide detail account information to the team at
  each meeting
• The account balance must be always positive (no
  debt allowed)
• Team members contribute initial funds to the
  account (e.g., 50 from each member the initial
  account value will be 200 for a four member
  team)
• Team members maintain positive account balance by
  subsequent incremental contributions
• Team member contributions must be equal across
  the team no exceptions

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Proposal

• Each team needs to prepare and defend a project
  proposal
• Proposal is a formal document explaining
• The need
• Proposed technological solution (Technical
  section)
• Team capability to undertake the effort
  (Administrative section)
• Proposal defense is a formal presentation
• Educate yourself on
• Technical solution you propose
• Top-down design process (system architecture,
  decomposition, synthesis)
• Systems engineering practice (project management)
• Look at the course web site for sample documents
• But be careful these docs are not perfect
  they will give you some clues only

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Proposal Preparation

• Your proposal is a formal document representing
  you !!!
• Dont forget about nice printout, cover, etc.
• Included drawings must be nice, clean and
  readable
• Look from a perspective that you compete for a
  limited pool of money
• It means, the best proposals win and get funded
• You have to attract a reader to your proposed
  work !!!!!!!!!
• Be realistic
• Say something about the team and your skills (any
  exceptional issues?)
• Write very well in a narrative form get English
  checked
• Particularly, pay attention to the Executive
  Summary

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Proposal Format

• Cover page
• Executive summary (1/2 1 page)
• Problem statement as an identification of need
  (1-2 pages)
• Approach (2-4 pages)
• Include problem analysis and requirements
  definition/analysis
• Mention briefly about alternative approaches and
  why you have chosen the proposed one
• Preliminary design (2-5 pages)
• Preliminary experimentation plan and evaluation
  criteria (1-2 pages)

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• Preliminary list and brief description of tasks
  and allocation of responsibilities (1-2 pages)
• Preliminary schedule and milestones (1 page)
• References
• Literature references
• Web URLs, etc.

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Proposal Presentation

• Limit your presentation to 20-30 minutes
• You must have two faculty members at the
  presentation
• All team members must speak at the proposal
  presentation distribute the load evenly, but do
  not switch speakers too frequently
• Your presentation must be professional
• It matters what you wear
• Use audio-visual equipment
• Distribute a copy of your proposal and slides
  before the presentation day (coordinate with FS)
• Use right size font and nice figures
• Book the room and find another faculty in advance

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Preparing for the Presentation

• Before you start developing the presentation,
  plan your strategy (creativity, brainstorming).
  Design it! You are telling the story!!!
• Analyze your audience - its the audience
  stupid!
• What are they interested in?
• What do they want from your talk?
• What does the audience know? What dont they
  know?
• What are the values of my audience?
• Determine main points
• Emphasize 2-5 main points in your talk.
• Structure your presentation to support these
  points

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Sample Presentation Content

• Follow your proposal content
• Introduction/motivation and identification of a
  need
• Main technical body including
• Requirements
• Top-level design and system architecture
• Alternative designs (any other you considered?)
• Identify main components and their role. How
  about interfaces?
• What are major challenges?
• Experimentation and testing approach
• Main administrative body
• List of tasks and allocation of responsibilities
• Schedule and milestones
• Skills of team members. What is an extra
  knowledge/skills to be acquired?
• Conclusions

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Extra Advice

• Use professionally prepared graphics
• Do not use PowerPoint CPU Wasters (extra
  visual effects, fancy combinations of them)
• Avoid the use of cue cards read directly from
  slides
• Meet the time constraints through the entire talk
  have control points
• Motivate your audience to listen. Stay excited.
• Practice your talk in front of your teammates,
  girlfriend/ boyfriend, family members
• Do not overprepare to the point of sounded
  scripted
• Practice the talk a night before, and do only a
  brief review of the material right before the
  talk
• You can tell a joke but watch out the ethics,
  etc.
• Prepare for the question and answer session