An easy-to-use solid modeler with tightly integrated surface modeling capabilities enabled Prisma Design International to model a prototype of the iRadio in 50 hours, about 25 hours faster than if a traditional CAD program had been used. Using the integrated modeling tools within Vellum Solids from Ashlar Inc., Austin, Texas, the designer was able to define a number of complex surfaces, stitch them together to form a solid object, then use the "shell solid" tool to offset the object by two millimeters, creating the walls of enclosure almost automatically. This same operation would have been very laborious with other CAD programs because offsetting an object leaves open edges that must be filled in by hand. "We met a tight deadline on the iRadio project and the modeling software was a big reason why," says Dan Caruthers, senior designer at Prisma Design. "Because I was able to mix solid and surface modeling techniques, I was able to create the digital model very quickly."
Prisma Design International, Inc., based in Tustin, California, was founded in October, 1997 by Gerhard Steinle, former head of Mercedes-Benz Advanced Design of North America, Inc. Steinle established that office in 1990 and served as its president until 1997. Prisma Design provides complete support and services for a variety of products in the transportation field, as well as for industrial products in general. Its spectrum of services includes: idea sketches and design renderings, ergonomic studies, trend studies (US and international), color and trim support, complete engineering, digital surfacing, digital modeling, full size and scale clay modeling, milling and stereolithography, full size and scale molding, mock-ups for exteriors and interiors, fabrication of functional mock-ups and running prototypes, locating manufacturing sources, and marketing and public relations support.
Internet radio for the car
Prisma Design was hired by Motorola to design a new type of electronic device for automobiles that combines entertainment, information, navigation, emergency calling, and communication into one system. Prisma Design faced a tight deadline on this project, called the iRadio(tm), because Motorola wanted to display a prototype at the Vortex Show less than two months away. In addition to the tight time frame, Prisma designers faced other challenges as well. "We didn't have the amount of freedom that we usually have for a new product," explains Steinle, the president of the firm. "We had to incorporate existing components and design around existing parts of an automobile." In this case it was the new model-year 2000 Mercedes-Benz S-Class and the iRadio had to fully blend into its interior environment.
The iRadio merges a number of technologies, including wireless, voice and data communications and global positioning systems, to deliver location-specific safety, information and entertainment services to drivers. Bluetooth technology allows seamless connection to cell phones, PDAs, and other consumer electronic equipment. iRadio can be customized to provide personalized news, audio directions, and real-time traffic reports. It is operated by driver-friendly, hands-free telephony and state-of-the-art voice recognition and text-to-speech technologies.
The designers working on the project began by creating hand sketches of different concepts. After the firm had settled on one promising idea, the next step was to create a digital model. The firm uses one of three programs for this: Studio from Alias/Wavefront, Rhino 3D or Vellum Solids. The latter was chosen for this project because, as Steinle says, "It is much simpler to use and modeling goes faster, so it was perfect for the iRadio where we had very little time."
Caruthers began modeling the iRadio by making quick, simple models of the iRadio's internal components "so I would have an idea of how the enclosure fit around them," he explains. "After I measured the components, it only took a few seconds to model them. I just defined a solid rectangle and marked features such as mounting holes." One of the features that made the modeling go so quickly was the program's user interface, which accomplishes most operations with fewer steps compared to other mid-range programs. Another time-saver is a patented feature called Drafting Assistant. By automatically identifying relationships such as endpoints, midpoints, center points, tangencies, and real and extended intersections, Drafting Assistant speeds geometry creation significantly.
"Drafting Assistant is a great feature," says Caruthers. " It was very helpful when I was modeling the iRadio." For example, when he needed to find the center point of a line, as the location to snap a line to, for instance, he simply moved his cursor to the general area. Tracking the cursor motion, the software asked if he wanted to select the center point. All he had to do was click the mouse and the software identified the precise location. Caruthers believes the Drafting Assistant in Vellum Solids is more powerful than similar tools in other programs because it gives the user much more control. "If I wanted to snap to the last 10 percent of a line, or the point where the last one-third of a line began, I could go to the Drafting Assistant's control screen and enter that specification," Caruthers says. "This kind of functionality makes Drafting Assistant the best of the "smart cursor" tools I have found."
Mix and match modeling methods
After Caruthers had modeled the internal components, the next step was to model the enclosure. If this project had been done in most midrange solid modeling programs, he would have modeled the enclosure strictly in solids since most of these programs have only limited surfacing functionality. Caruthers would have created many different solid primitives representing various pieces of the enclosure. After positioning them correctly in relation to each other, he would have used Boolean commands to join them.
Instead, he created a series of 2D lines and curves representing the cross section of the enclosure and then began using Vellum Solids surface modeling tools. Unlike other mid-range CAD systems with only rudimentary surfacing functionality, Vellum Solids has extensive surface modeling tools. And unlike some high-end systems where surface modeling and solid modeling exist in separate modules, Vellum Solids features a unified working environment in which all tools are always accessible from one of three palettes: the basic drawing palette, the surface modeling palette, and the solid modeling palette. This approach offers the flexibility to use the most appropriate modeling method at all times. Also, the program never makes the user transfer from one mode to another, such as from sketch mode, to part mode, to assembly mode, to draft mode. All the tools needed to go from art to part are accessible from the same place.
"I used many of the surface modeling tools. Some of the more advanced ones, such as 'Sweep-2rails,' were particularly helpful because they let me create complex surfaces quite easily," Caruthers explains. "Sweep-2rails" enabled him to draw to lines that formed the boundaries of the surface and use one of the curves created earlier as the third line representing the surface profile. After selecting these three lines, Caruthers invoked the " Sweep-2rails" tool to automatically generate the surface.
Caruthers created a number of separate surfaces representing different areas of the enclosure. Then he selected all the surfaces and clicked the "stitch" tool. The software automatically stitched all the surfaces together into one large solid block. The next step was to turn this block into the shell that would become the enclosure. This was just a matter of selecting the solid, invoking the shelling command, and telling the software how thick to make the shell walls. Although other midrange modelers offer a shelling feature, many could not shell a part as complex as this enclosure. The designer would have been forced to shell a simpler model and add any complex shapes later. "Also, with most other programs if you offset an object, the edges are open so you have to fill in the gaps by hand," Caruthers says. "That can be very time-consuming."
As Caruthers fine-tuned the design, other modeling tools, including the easy-to-use filleting tool, came into play. For example, there is a directional button on the front of the iRadio. Above it are two grooves that originally started off as sharp points with a zero radius. Later they were modified to incorporate a two to three millimeter radius. "Vellum's filleting tool is much easier to understand than those in other software," Caruthers says. "I just clicked on one edge of the groove, then clicked where I wanted the radius to start. Then I entered a value for the radius. With just two clicks of the mouse and the entry of a number, I had the surface I wanted."
Prisma Design met the deadline and the iRadio, nicely integrated into the model-year 2000 Mercedes-Benz S-Class was shown at the Vortex Show in Laguna Niguel. The design was modified and the iRadio was shown again at the Consumer Electronics Show. The prototype is now in its third iteration and Motorola expects it will reach consumers within a year or two. It will be installed on certain vehicles as original equipment by the auto makers. Caruthers and Steinle believe that Vellum Solids allowed them to complete this project significantly faster than if they had used a conventional CAD program. They estimate that the software's Drafting Assistant, along with its sophisticated surface modeling capabilities, integrated modeling environment, and advanced tools such as "shell solid" cut 25 hours off the design time.