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Prototyping. ME110 Spring 2003. Product Development Process. Concept Development. System-Level Design. Detail Design. Testing and Refinement. Production Ramp-Up. Planning. Prototyping is done throughout the development process. Spiral Model of Product Development.

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Prototyping

ME110

Spring 2003


Product Development Process

Concept

Development

System-Level

Design

Detail

Design

Testing and

Refinement

Production

Ramp-Up

Planning

Prototyping is done throughout the development process.


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


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 team’s schedule

    • e.g., first testable hardware


Physical

Types of Prototypes

alpha

prototype

beta

prototype

ball

support

prototype

final

product

trackball mechanism

linked to circuit

simulation

Focused

Comprehensive

simulation

of trackball

circuits

not

generally

feasible

equations

modeling ball

supports

Analytical


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.

Physical vs. Analytical 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.

Focused vs. Comprehensive Prototypes


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


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.


Profs. Jen Mankoff and James Landay, CS

Fidelity in Prototyping

  • Fidelity refers to the level of detail

  • High fidelity?

    • prototypes look like the final product

  • Low fidelity?

    • artists renditions with many details missing


Profs. Jen Mankoff and James Landay, CS

Low-fi Storyboards for User Interface Interactions

  • Where do storyboards come from?

    • film & animation

  • Give you a “script” of important events

    • leave out the details

    • concentrate on the important interactions


Profs. Jen Mankoff and James Landay, CS

Why Use Low-fi Prototypes?

  • Traditional methods take too long

    • sketches -> prototype -> evaluate -> iterate

  • Can simulate the prototype

    • sketches -> evaluate -> iterate

    • sketches act as prototypes

      • designer “plays computer”

      • other design team members observe & record

  • Kindergarten implementation skills

    • allows non-programmers to participate


Profs. Jen Mankoff and James Landay, CS

Hi-fi Prototypes Warp

  • 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


Profs. Jen Mankoff and James Landay, CS

Wizard of Oz Technique (?)

  • 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


Profs. Jen Mankoff and James Landay, CS

The Basic Materials for Low-fi Prototyping of Visual UIs

  • 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.


Profs. Jen Mankoff and James Landay, CS

Constructing the Model

  • Set a deadline

    • don’t 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


Profs. Jen Mankoff and James Landay, CS

ESP

Low-fi Prototypes


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


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


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?


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


Simulations of all Operations


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.

    • SLA=Stereolithography Apparatus (Cory Hall, Prof. Carlo Sequin)

    • Solid Imaging (Cory Hall, Prof. Carlo Sequin)

    • SLS=Selective 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...


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.


SLA=Stereolithography 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.


Prof. Carlo Séquin, CS

Stereolithography (SLA)

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


Prof. Carlo Séquin, CS

Stereolithography Evaluation

  • Can do intricate shapes with small holes

  • High precision

  • Moderately Fast

  • Photopolymer is expensive ($700/gallon)

  • Laser is expensive ($10’000),lasts only about 2000 hrs.


Injection-Molded Housing for ST TouchChip

Prof. Carlo Séquin, CS

Model  Prototype  Mold  Part


Prof. Carlo Séquin, CS

Séquin’s “Minimal Saddle Trefoil”

  • Stereo-lithography master


Prof. Carlo Séquin, CS

Séquin’s “Minimal Saddle Trefoil”

  • bronze cast, gold plated


Prof. Carlo Séquin, CS

Solid Imaging: Thermojet Printing

  • 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)


Prof. Carlo Séquin, CS

Solid Imaging Example

  • That’s how partsemerge from theThermojet printer

  • After partial removalof the supportingscaffolding


Prof. Carlo Séquin, CS

9-Story Intertwined Double Toroid

Bronze investment

casting from wax original made on 3D Systems’“Thermojet”


Prof. Carlo Séquin, CS

Solid Imaging Evaluation

  • An Informal Evaluation

  • Fast

  • Inexpensive

  • Reliable, robust

  • Good for investment casting

  • Support removal takes some care(refrigerate model beforehand)

  • Thermojet 88 parts are fragile


Prof. Carlo Séquin, CS

3D Printing: Some Key Players

  • 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.


Prof. Carlo Séquin, CS

3D Printing:Z Corporation

The Z402 3D Printer

  • Speed: 1-2 vertical inches per hour

  • Build Volume: 8" x 10" x 8"

  • Thickness: 3 to 10 mils, selectable


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.


Prof. Carlo Séquin, CS

3D Printing:Z Corporation


Digging out

Prof. Carlo Séquin, CS

3D Printing:Z Corporation


Keep some powder in place

Prof. Carlo Séquin, CS

Optional Curing: 30 min. @ 200ºF

<-- Tray for transport


Cleaning up in the de-powdering station

Prof. Carlo Séquin, CS

3D Printing:Z Corporation


Prof. Carlo Séquin, CS

3D Printing:Z Corporation

The finished part

  • Zcorp,

  • 6” diam.,

  • 6hrs.


Prof. Carlo Séquin, CS

120 Cell -- Close-up


Use compressed air to blow out central hollow space.

Prof. Carlo Séquin, CS

3D Color Printing: Z Corporation


Prof. Carlo Séquin, CS

3D Color Printing: Z Corporation

Infiltrate Alkyl Cyanoacrylane Ester = “super-glue” to harden parts and to intensify colors.


Prof. Carlo Séquin, CS

What Can Go Wrong ?

  • Blocked glue lines

  • Crumbling parts


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 !

  • Lot’s of dust everywhere ...


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


Prof. Carlo Séquin, CS

Fused Deposition Modeling

Stratasys: http://www.stratasys.com/


Prof. Carlo Séquin, CS

Looking into the FDM Machine


Support material

Prof. Carlo Séquin, CS

Layered Fabrication of Klein Bottle


Prof. Carlo Séquin, CS

Klein Bottle Skeleton (FDM)


Prof. Carlo Séquin, CS

Fused Deposition Modeling (FDM) Evaluation

  • 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 !


Black blobs

Toppled supports

Prof. Carlo Séquin, CS

What Can Go Wrong ?


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