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
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