Prototyping ME110 Spring 2003

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

Risk Analysis Prototype 1 Prototype 3 Prototype 2 Operational Prototype Risk Analysis Risk Analysis Risk Analysis Simulations, models, benchmarks Determine objectives, alternatives, constraints Plan next phasesDevelop, verify Evaluate alternatives, identify, resolve risks Concept Requirements Plan Development Plan Integration and test plan Requirements Validation Design Validation and Verification Final Code Implementation and 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 final product beta prototype alpha prototype ball support prototype simulation of trackball circuits equations modeling ball supports trackball mechanism linked to circuit simulation not generally feasible

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 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 Profs. Jen Mankoff and James Landay, CS

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: 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. Prof. Carlo Séquin, CS

Model  Prototype  Mold  Part Injection-Molded Housing for ST TouchChip 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 parts emerge from the Thermojet printer After partial removal of the supporting scaffolding 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

3D Printing: Some Key Players Soligen: Metal and ceramic powders for operational prototypes. Z Corporation: 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 Prof. Carlo Séquin, CS

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.

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

3D Printing: Z Corporation Digging out Prof. Carlo Séquin, CS

Optional Curing: ºF Keep some powder in place <-- Tray for transport Prof. Carlo Séquin, CS

3D Printing: Z Corporation Cleaning up in the de-powdering station Prof. Carlo Séquin, CS

3D Printing: Z Corporation The finished part u Zcorp, u 6” diam., u 6hrs. Prof. Carlo Séquin, CS

120 Cell -- Close-up Prof. Carlo Séquin, CS

3D Color Printing: Z Corporation Use compressed air to blow out central hollow space. 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 Prof. Carlo Séquin, CS

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: Prof. Carlo Séquin, CS

Looking into the FDM Machine Prof. Carlo Séquin, CS

Layered Fabrication of Klein Bottle Support material 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 !

What Can Go Wrong ? Black blobs Toppled supports Prof. Carlo Séquin, CS