Prototyping

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Prototyping

• ME110
• Spring 2003

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Product Development Process
Concept Development
System-Level Design
Detail Design
Testing and Refinement
Production Ramp-Up
Planning
Prototyping is done throughout the development
process.
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Spiral Model of Product Development
Determine objectives, alternatives, constraints
Evaluate alternatives, identify, resolve risks
Risk Analysis
Risk Analysis
Risk Analysis
Operational Prototype
Prototype 3
Prototype 2
Risk Analysis
Prototype 1
Simulations, models, benchmarks
Requirements Plan
Concept
Development Plan
Requirements Validation
Integration and test plan
Design Validation and Verification
Final Code Implementation and Test
Plan next phases
Develop, verify
Adapted from B. Boehm
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Four Uses of Prototypes

• Learning
• answering questions about performance or
  feasibility
• e.g., proof-of-concept model
• Communication
• demonstration of product for feedback visual,
  tactile, functional
• e.g., 3D physical models of style or function
• Integration
• combination of sub-systems into system model
• e.g., alpha or beta test models
• Milestones
• goal for development teams schedule
• e.g., first testable hardware

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Types of Prototypes
Physical
beta prototype
alpha prototype
ball support prototype
final product
trackball mechanism linked to circuit simulation
Comprehensive
Focused
simulation of trackball circuits
not generally feasible
equations modeling ball supports
Analytical
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Physical vs. Analytical Prototypes

• Physical Prototypes
• Tangible approximation of the product.
• May exhibit unmodeled behavior.
• Some behavior may be an artifact of the
  approximation.
• Often best for communication.

• Analytical Prototypes
• Mathematical model of the product.
• Can only exhibit behavior arising from explicitly
  modeled phenomena. (However, behavior is not
  always anticipated.
• Some behavior may be an artifact of the
  analytical method.
• Often allow more experimental freedom than
  physical models.

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Focused vs. Comprehensive Prototypes

• Focused Prototypes
• Implement one or a few attributes of the product.
• Answer specific questions about the product
  design.
• Generally several are required.

• Comprehensive Prototypes
• Implement many or all attributes of the product.
• Offer opportunities for rigorous testing.
• Often best for milestones and integration.

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Concept Prototypes Can Be Communicated in
Multiple Ways

• Verbal descriptions
• Sketches
• Photos and renderings
• Storyboards a series of images that
  communicates a temporal sequence of actions
  involving the product
• Videos dynamic storyboards
• Simulation
• Interactive multimedia combines the visual
  richness of video with the interactivity of
  simulation
• Physical appearance models
• Working prototypes

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Traditional Prototyping Methods

• Model from clay
• Carve from wood or styrofoam
• Bend wire meshing
• CNC machining (pastic or aluminum)
• Rubber molding urethane casting
• Materials wood, foam, plastics, etc.
• Model making requires special skills.

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Fidelity in Prototyping
Profs. Jen Mankoff and James Landay, CS

• Fidelity refers to the level of detail
• High fidelity?
• prototypes look like the final product
• Low fidelity?
• artists renditions with many details missing

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Low-fi Storyboards for User Interface Interactions
Profs. Jen Mankoff and James Landay, CS

• Where do storyboards come from?
• film animation
• Give you a script of important events
• leave out the details
• concentrate on the important interactions

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Why Use Low-fi Prototypes?
Profs. Jen Mankoff and James Landay, CS

• Traditional methods take too long
• sketches -gt prototype -gt evaluate -gt iterate
• Can simulate the prototype
• sketches -gt evaluate -gt iterate
• sketches act as prototypes
• designer plays computer
• other design team members observe record
• Kindergarten implementation skills
• allows non-programmers to participate

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Hi-fi Prototypes Warp
Profs. Jen Mankoff and James Landay, CS

• Perceptions of the customer/reviewer?
• formal representation indicates finished nature
• comments on color, fonts, and alignment
• Time?
• encourage precision
• specifying details takes more time
• Creativity?
• lose track of the big picture

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Wizard of Oz Technique (?)
Profs. Jen Mankoff and James Landay, CS

• Faking the interaction. Comes from?
• from the film The Wizard of OZ
• the man behind the curtain
• Long tradition in computer industry
• prototype of a PC w/ a VAX behind the curtain
• Much more important for hard to implement
  features
• Speech handwriting recognition

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The Basic Materials for Low-fi Prototyping of
Visual UIs
Profs. Jen Mankoff and James Landay, CS

• Large, heavy, white paper (11 x 17)
• 5x8 in. index cards
• Tape, stick glue, correction tape
• Pens markers (many colors sizes)
• Overhead transparencies
• Scissors, X-acto knives, etc.

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Constructing the Model
Profs. Jen Mankoff and James Landay, CS

• Set a deadline
• dont think too long - build it!
• Draw a window frame on large paper
• Put different screen regions on cards
• anything that moves, changes, appears/disappears
• Ready response for any customer action
• e.g., have those pull-down menus already made
• Use photocopier to make many versions

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Low-fi Prototypes
Profs. Jen Mankoff and James Landay, CS
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High Performance Companies

• Not only verify that the final product meets
  customer expectations,
• But involve potential customers directly in
  various stages of development and encourage
  partnerships
• Which allows faster cycling for customer feedback
• And creates better-suited products

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Virtual Prototyping

• 3D CAD models enable many kinds of analysis
• Fit and assembly
• Manufacturability
• Form and style
• Kinematics
• Finite element analysis (stress, thermal)
• Crash testing
• more every year...
• Simulation, Optimization

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Boeing 777 Testing

• Rapid design-build philosophy
• 100 digital CAD 3D modeling
• Part Interference
• Brakes Test
• Minimum rotor thickness
• Maximum takeoff weight
• Maximum runway speed
• Will the brakes ignite?
• Wing Test
• Maximum loading
• When will it break?
• Where will it break?

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CATIA CAD Modeling Analysis

• 100 digital design on the Boeing 777
• Used to discover tolerance error early in the
  design cycle
• Greatly reduced the number of design changes and
  costs

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Simulations of all Operations
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Physical Rapid Prototyping Methods

• Build parts in layers based on CAD model.
• Conceptually, like stacking many tailored pieces
  of cardboard on top of one another.
• SLAStereolithography Apparatus (Cory Hall, Prof.
  Carlo Sequin)
• Solid Imaging (Cory Hall, Prof. Carlo Sequin)
• SLSSelective Laser Sintering
• FDM Fused Deposition Modeling (Tour - Etcheverry
  Hall, Prof. Paul Wright)
• Color/Mono 3D Printing (e.g., Z-Corp) (Tour -
  Etcheverry Hall)
• Solid Injection Molding
• Others every year...

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Selective Laser Sintering

• Thermoplastic powder is spread by a roller over
  the surface of a build cylinder.
• The piston in the cylinder moves down one object
  layer thickness to accommodate the new layer of
  powder.
• A laser beam is traced over the surface of this
  tightly compacted powder to selectively melt and
  bond it to form a layer of the object.
• Excess powder is brushed away and final manual
  finishing may be carried out.

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SLAStereolithography Apparatus

• Builds plastic parts or objects a layer at a time
  by tracing a laser beam on the surface of a vat
  of a photosensitive liquid polymer.
• Photopolymer quickly solidifies wherever the
  laser beam strikes the surface of the liquid.
• Repeated by lowering a small distance into the
  vat and a second layer is traced right on top of
  the first.
• Self-adhesive property of the material causes the
  layers to bond to one another and eventually form
  a complete, three-dimensional object after many
  such layers are formed.

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Stereolithography (SLA)
Prof. Carlo Séquin, CS

• SLA Machine by 3D Systems
• Maximum build envelope
  350 x 350 x 400 mm in XYZ
• Vertical resolution 0.00177 mm
• Position repeatability 0.005 mm
• Maximum part weight 56.8 kg

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Stereolithography Evaluation
Prof. Carlo Séquin, CS

• Can do intricate shapes with small holes
• High precision
• Moderately Fast
• Photopolymer is expensive (700/gallon)
• Laser is expensive (10000),lasts only about
  2000 hrs.

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Model ? Prototype ? Mold ? Part
Prof. Carlo Séquin, CS

• Injection-Molded Housing for ST TouchChip

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Séquins Minimal Saddle Trefoil
Prof. Carlo Séquin, CS

• Stereo-lithography master

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Séquins Minimal Saddle Trefoil
Prof. Carlo Séquin, CS

• bronze cast, gold plated

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Solid Imaging Thermojet Printing
Prof. Carlo Séquin, CS

• Technology Multi-Jet Modeling (MJM)
• Uses plastic and wax.
• Need to build a support structures where there
  are overhangs / bridges that must be removed
  manually.
• Resolution (x,y,z) 300 x 400 x 600 DPI
• Maximum Model Size 10 x 7.5 x 8 in (13 lb)

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Solid Imaging Example
Prof. Carlo Séquin, CS

• Thats how partsemerge from theThermojet
  printer
• After partial removalof the supportingscaffoldin
  g

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9-Story Intertwined Double Toroid
Prof. Carlo Séquin, CS

• Bronze investment
• casting from wax original made on 3D
  SystemsThermojet

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Solid Imaging Evaluation
Prof. Carlo Séquin, CS

• An Informal Evaluation
• Fast
• Inexpensive
• Reliable, robust
• Good for investment casting
• Support removal takes some care(refrigerate
  model beforehand)
• Thermojet 88 parts are fragile

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3D Printing Some Key Players
Prof. Carlo Séquin, CS

• Soligen http//www.zcorp.com/Metal and ceramic
  powdersfor operational prototypes.
• Z Corporation http//www.zcorp.com/Plaster and
  starch powders for visualization models.
• Needs no supports that must be removed!
• Uniform bed of powder acts as support.
• This powder gets selectively (locally) glued (or
  fused) together to create the solid portions of
  the desired part.

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3D Printing Z Corporation
Prof. Carlo Séquin, CS

• The Z402 3D Printer
• Speed 1-2 vertical inches per hour
• Build Volume 8" x 10" x 8"
• Thickness 3 to 10 mils, selectable

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Three Dimensional Printing

• A layer of powder object material is deposited at
  the top of a fabrication chamber.
• Roller then distributes and compresses the powder
  at the top of the fabrication chamber.
• Multi-channel jetting head subsequently deposits
  a liquid adhesive in a two dimensional pattern
  onto the layer of the powder which becomes bonded
  in the areas where the adhesive is deposited, to
  form a layer of the object.

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3D Printing Z Corporation
Prof. Carlo Séquin, CS
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3D Printing Z Corporation
Prof. Carlo Séquin, CS

• Digging out

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Optional Curing 30 min. _at_ 200ºF
Prof. Carlo Séquin, CS

• Keep some powder in place

• lt-- Tray for transport

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3D Printing Z Corporation
Prof. Carlo Séquin, CS

• Cleaning up in the de-powdering station

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3D Printing Z Corporation
Prof. Carlo Séquin, CS

• The finished part

• Zcorp,
• 6 diam.,
• 6hrs.

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120 Cell -- Close-up
Prof. Carlo Séquin, CS
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3D Color Printing Z Corporation
Prof. Carlo Séquin, CS

• Use compressed air to blow out central hollow
  space.

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3D Color Printing Z Corporation
Prof. Carlo Séquin, CS

• Infiltrate Alkyl Cyanoacrylane Ester
  super-glue to harden parts and to intensify
  colors.

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What Can Go Wrong ?
Prof. Carlo Séquin, CS

• Blocked glue lines
• Crumbling parts

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3D Printing (Z Corporation) Evaluation

• Fast !
• Running expenses moderate,(but overpriced
  powder)
• Color print head and tubes need some care in
  maintenance.
• Somewhat messy cleanup !
• Lots of dust everywhere ...

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Fused Deposition Modeling

• ABS Plastic is supplied (as beads or filament)
  to an extrusion nozzle.
• The nozzle is heated to melt the plastic and has
  a mechanism which allows the flow of the melted
  plastic to be turned on and off.
• As the nozzle is moved over the table in the
  required geometry, it deposits a thin bead of
  extruded plastic to form each layer.
• The plastic hardens immediately after being
  squirted from the nozzle and bonds to the layer
  below.

acrylonitrile-butadine-styrene
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Fused Deposition Modeling
Prof. Carlo Séquin, CS

• Stratasys http//www.stratasys.com/

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Looking into the FDM Machine
Prof. Carlo Séquin, CS
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Layered Fabrication of Klein Bottle
Prof. Carlo Séquin, CS

• Support material

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Klein Bottle Skeleton (FDM)
Prof. Carlo Séquin, CS
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Fused Deposition Modeling (FDM) Evaluation
Prof. Carlo Séquin, CS

• Easy to use
• Rugged and robust
• Could have this in your office
• Good transparent software (Quickslice)with
  multiple entry points STL, SSL, SML
• Inexpensive to operate
• Slow
• Think about support removal !

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What Can Go Wrong ?
Prof. Carlo Séquin, CS

• Black blobs
• Toppled supports