Prototyping ME110 Spring 2003. Planning Concept Development Concept Development System-Level Design...

Prototyping

ME110

Spring 2003

PlanningPlanning ConceptDevelopment

ConceptDevelopment

System-LevelDesign

System-LevelDesign

DetailDesign

DetailDesign

Testing andRefinement

Testing andRefinement

ProductionRamp-Up

ProductionRamp-Up

Prototyping is done throughout the development process.

Product Development Process

RiskAnalysis Prototype 1

Prototype 3Prototype

2

OperationalPrototype

RiskAnalysis

RiskAnalysis

RiskAnalysis

Simulations, models, benchmarks

Determine objectives,alternatives, constraints

Plan next phases Develop, verify

Evaluate alternatives,identify, resolve risks

ConceptRequirements

Plan

DevelopmentPlan

Integrationand test plan

RequirementsValidation

Design Validationand Verification

Final Code Implementationand Test

Adapted from B. Boehm

Spiral Model of Product Development

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

Types of Prototypes

ComprehensiveFocused

Physical

Analytical

finalproduct

betaprototype

alphaprototype

ballsupport

prototype

simulationof trackball

circuits

equationsmodeling ball

supports

trackball mechanismlinked to circuit

simulation

notgenerallyfeasible

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.

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.

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.

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


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


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


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


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.


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


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.

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.


Model Prototype Mold Part

Injection-Molded Housing for ST TouchChip


Séquin’s “Minimal Saddle Trefoil”

Stereo-lithography master


Séquin’s “Minimal Saddle Trefoil”

bronze cast, gold plated


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)


Solid Imaging Example

That’s how partsemerge from theThermojet printer

After partial removalof the supportingscaffolding



9-Story Intertwined Double Toroid

Bronze investment casting from wax original

made on 3D Systems’“Thermojet”


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

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.


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.


Digging out


Optional Curing: 30 min. @ 200ºF

Keep some powder in place

<-- Tray for transport



Cleaning up in the de-powdering station



The finished part Zcorp,

6” diam.,

6hrs.


120 Cell -- Close-up


3D Color Printing: Z Corporation

Use compressed air to blow out central hollow space.


3D Color Printing: Z Corporation

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


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

Fused Deposition Modeling

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


Looking into the FDM Machine


Layered Fabrication of Klein Bottle

Support material


Klein Bottle Skeleton (FDM)



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 !

What Can Go Wrong ?

Black blobs

Toppled supports


Prototyping ME110 Spring 2003. Planning Concept Development Concept Development System-Level Design...

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