Technical alliances spark drive for interactive TV
Newton, MA--Broadband communications networks are about to change the way people work, learn, and are entertained. How will this happen? By transforming the ordinary television set into a high-speed, two-way communications tool.
As the newest addition to the information super-highway infrastructure, interactive TV promises to replace passive, mass communications with interactive, targeted communications. With ITV, for example, Courtroom Television can enhance its televised trials via on-screen overlays. Using a remote, viewers would be able to call up definitions of legal terms, or scan the biographies of lawyers.
Interactive TV will also let viewers select movies and videos from vast program libraries; purchase tickets for concerts and ball games; or buy products directly from home.
Implementation of such systems involves three key components: a digital home-entertainment terminal that connects to an existing TV receiver; a video server, designed to deliver content to the home over the network; and the network itself, supplied by a telephone or cable company.
It's the home-entertainment terminal that the consumer uses and sees as the embodiment of interactive TV. Built by Thomson, Apple, Mitsubishi, Zenith, General Instrument, and other consumer electronics giants, these set-top units decode the incoming stream of digital MPEG-2 (Motion Pictures Experts Group) compressed video signals and data.
The challenge of designing the set-top unit, says Brian Smith of Philips Consumer Electronics Co., involves both software and hardware issues. As an example, Smith cites RFI considerations due to the analog and digital circuitry inside the box, as well as possible leakage from the power cord and other connecting wires. "A digital set-top box is essentially a big computer," he explains, "and it's sitting in the worst possible place--on top of the television set. Layout and shielding are critical."
As for software, the operating system has to be robust enough that nothing can crash it. "You better not allow an errant application to do things it's not supposed to do," Smith warns. "This is not a PC that you can reboot, but a consumer product."
Large capacity needed. Other challenges face video-server designs. Supplied to telecommunications and cable companies by vendors of distributed computing technologies, these systems feature computers with enough storage and software to coordinate the delivery of video streams across a network. Examples are Digital's open Mediaplex™ servers, SUN's SPARC™ server family, and Challenge™ servers from Silicon Graphics.
Technical hurdles relating to video servers involve software, reports Roger Horine of Digital Equipment Corporation's Video and Interactive Information services. "The big challenge is being able to insure that subscriber requests are handled very quickly. Since these video assets may or may not be on a server near the subscriber, the overall network of video servers has to be able to efficiently move them around."
Compatibility with existing and emerging industry standards is another big factor in server development, says Rob Goedman, VP of Systems Integration at the Thomson Sun Interactive Alliance. "One of the most important issues that remains to be solved with regard to interactive TV," he reports, "is the setting of standards and coming to agreements as to how contents will play on many different set-top boxes."
Players join forces. To accelerate delivery and widespread use of interactive information services, key software and hardware providers have formed alliances. For instance, the expertise and complementary technologies of Sun Microsystems (network management and SPARC video servers) and Thomson (consumer electronics and digital set-top decoders) has resulted in a jointly designed, digital interactive TV system, from server to decoder.
Unveiled this past January at the 1995 Consumer Electronics Show, Las Vegas, the Thomson/Sun "Open TV" system is claimed to be the first working interactive system based on commercially available products and technologies to be offered to network operation and content providers. Irdet, the technology division of Nethold, a Dutch-based subscription television group with more than 2.4 million subscribers, recently announced its intention to license the Open TV system, reaching viewers in Europe and South Africa.
Industry alliances to develop interactive programming are also critical in promoting ITV technology, says Digital's Horine. "There is a chicken-and-egg problem here, where content developers don't want to go whole hog into producing content for interactive TV until there are a lot of subscribers. On the other hand," he points out, "telephone companies are reluctant to make the huge investments needed until there is content."
Even so, telecommunications and cable companies are busy upgrading their networks to accommodate delivery of interactive TV services. A case in point is the switched digital network introduced this year by Bell Atlantic Corp. in Dover Township, NJ. The fiber-based network, supplied by BroadBand Technologies Inc., will initially carry 96 broadcast stations and cable programming services to approximately 38,000 homes.
ITV works over switched digital networks
Open standards allow connection to many digital services
Still to come: Full VCR control over selected video streams
FutureVision, the system's first video information provider, will digitally encode the analog feeds of off-air broadcast stations and satellite-delivered cable programming. These digitized signals connect to file servers capable of generating interactive prompts which TV programmers use to create on-screen overlays synchronized with programming and advertising.
Such early deployments of ITV will allow users to play along with game shows, select instant replay from sporting events, or choose from a library of movies. However, "full interactivity with VCR control over directly selected video streams," says Thomson's Goedman, "will not happen for another three or four years, until there is further development of standards and fiber-based infrastructures."
--David J. Bak, Senior Editor
Tandem pump halves size requirement
New Holland, PA--A new lube and charge pump system from Commercial Intertech Corp., Youngstown, OH, is half the size of other pumps of comparable displacement, the company claims. Commercial engineers custom-designed the pump for the hydraulic system of the Genesis™ 70 series tractors from New Holland North America Inc. The new system also supports New Holland's MegaFlow™ option, which delivers 55 gallons per minute at 2,750 psi.
To meet the tractor design's space constraints, Commercial engineers opted to custom-design the lube and charge pump. The pump operates at low pressures and does not require the journal-bearing capacity of high-pressure pumps.
"Early in the design, it became apparent that a tandem pump with just one inlet was the design choice for best accessibility, serviceability, and reduced plumbing costs," says John Boop, Manager of International Technology for Commercial Intertech. "The real challenge was to design a tandem pump with greatly reduced length to fit in the small space allowed, while still maintaining structural integrity and reliability."
Engineers met the challenge by shortening the journal bushings and re-designing the housings and end covers. "Designing specifically for low pressure achieved the economy of size we want- ed and resulted in a high-capacity, high-density pump," says Boop.
The pump's cast-iron construction eliminates the need for thrust plates for sealing the charge section of the pump, and improves its high-temperature efficiency.
Unlike tractors that put the full hydraulic load on one pump, Genesis tractors with the MegaFlow option operate two main pumps simultaneously. The two main pumps allow for the operation of a low-flow/high-pressure system from one remote, and a high-flow/low-pressure system from another. The tractors are available in the U.S. and Europe, and are offered in four models from 145 to 210 horsepower.
--Adele Hars, European Editor, France
Van collects data continuously at 30 mph
Villanterio, Italy--Why hire a survey team when you can collect road data continuously in the comfort of a FIAT Ducato van? For applications such as road-sign surveys or the preliminary work for laying down fiber-optic cable, the DAVIDE van can acquire images from the surrounding landscape and road network, compress them, and store them on a digital tape complete with position reference and time stamp.
Designed by GRAFTEK Italia, the van's differential GPS (Global Positioning Satellite) system receiver, inertial platform, and dual odometers give it a position accuracy of 1m. Four fixed CCD cameras pointing right, left, front, and rear; two still digital cameras; and one movable CCD camera are mounted on the vehicle. The five color CCD cameras acquire images continuously; the digital cameras acquire stereographic images on the operator's voice command. "The voice interface for commands is an important safety feature for a moving vehicle," notes GRAFTEK President Ignazio Piacentini.
Three computers on an Ethernet network are also on board: one Pentium-based computer for the voice interface, man-machine interface (MMI), and maps; and two Macintosh Quadra 950s for JPEG image compression and image processing. Designers developed the MMI using LabVIEW graphical programming software from National Instruments, Austin, TX. In fact, LabVIEW applications run on all three computers.
"You can add other sensors to the van to map anything that's capable of being sensed, such as air pollution or RF fields," says Piacentini.
French firm targets electric-vehicle niches
Paris--Much of the current debate surrounding electric vehicles addresses their viability for mass-market consumers. But two French companies have a different approach, choosing instead to target niche markets. Radio Energie, Marcoussis, has developed a "switched reluctance" (SR) variable-speed drive for high-torque/low-speed vehicles. And, Technicrea, Belfort, has designed an "electric wheel" especially for all-terrain vehicles.
Electric drives that are powerful enough for heavy-equipment applications are often too big, too power-hungry, or too unreliable for many uses. Radio-Energie worked to develop a solution addressing all these issues.
The result is an ensemble consisting of a switched reluctance (SR) motor called the MRV (moteur ŕ reluctance variable), and an electronic controller.
"The SR motor is a brushless dc motor that provides the performance of a fully controlled dc motor, and can replace a dc motor of a much bigger size," explains Marketing Manager Pierre Chamagne. "Furthermore, it combines these qualities with the robustness and reliability of an ac induction motor."
The motor is four phase, with an 8-pole stator and a 6-salient-pole rotor. The rotor is a lamination stack without windings. Its low inertia gives it good acceleration with no copper loss and negligible iron loss. It runs by the application of energy to two opposite stator windings, creating a flux that attracts two opposite rotor poles to produce motor torque. The application of energy is accurately timed by two sensors that interact with a revolving, segmented ring to generate digital signals indicating rotor position. Through the power switches, the logic circuit then energizes the appropriate coil pair for the most torque-effective current pulses.
The sensors also provide information that the controller, which is totally digital and programmable, uses to produce firing signals. The system can be configured so that current flows in both directions from the battery leads. This means that the motor effectively acts as a generator, producing braking torque on the shaft and returning energy to the battery.
"The output power is 1 kW at 3,000 rpms, with a starting torque of 25 Nm," explains Claude Poirson, chairman and CEO, who led the development team. "The fully digital controller and the intelligent power bridge are both highly integrated. Associated with the very simple structure of the SR motor, the system is a low-cost, reduced-size, reliable and practically maintenance-free drive."
Electric wheel. Technicrea originally developed its "electric wheel" for the French army, which wanted a system to replace mechanical traction for tanks. By integrating a motor in each wheel of the vehicle, engineers eliminated all mechanical transmission systems for propulsion. This offers savings of space, weight, price and efficiency, explains project leader Pierre Bey.
An added benefit of this design is that each wheel can rotate freely 180o around its vertical axis. This introduces a whole new range of movement: Such a vehicle can even move completely sideways, like a crab, and climb over obstacles--regardless of the direction in which it is travelling.
To create this system, the company designed a 20-kW brushless synchro- nous motor with permanent NdFeB magnets for a good torque/weight ratio.
The stator is internal; the rotor turns around it, simplifying the mechanical design. The shaft is near the stator iron sheets, while the wheel is directly linked to the rotor. The airgap radius is large, for good electro-magnetic torque. The magnets, which are on the internal face of the magnetic rotor yoke, are naturally air-cooled. The stator is cooled by liquid flowing directly in the bottom of the bars above the insulation, allowing for the use of NdFeB magnets and high current density in the stator, and therefore high torque.
The electronic supply consists of a two-stage inverter, wherein a square voltage inverter is connected to cycloconverters. The design allows for soft commutation of the switches, without the need for reactive elements, reducing EMI/RFI interference.
2-D CAD cuts time for camera, TV design
Tokyo--With all the reputed advantages 3-D design software offers, not every project requires it. In fact, some industry sources say, many engineers do most of their design work in 2-D. That's the case at two Japanese companies, Olympus Optical Company, Ltd, Ina; and Sony, Tokyo.
"I don't need 3-D right now," says Ryusuke Nozawa, manager of Olympus' production engineering department. Responsible for development of tooling molds and dyes for camera and endoscope lenses, his department uses Micro Cadam as well as EDS Unigraphics. He says Micro Cadam has helped his department cut tooling design from eight months to two months. The most recent commercial product he has worked on: The L10 camera.
Quality is Nozawa's major concern in tooling design, and he says Micro Cadam helps engineers ensure that quality by enabling them to do multiple design iterations.
Other engineers at Olympus say that Micro Cadam's ACCESS architecture has helped shorten design time through the streamlining of the information-management system. At Olympus, all information related to lens processing is included in a "summary table." The table takes its information from the Micro Cadam parts-drawing database. ACCESS automatically generates necessary jigs and materials drawings from information registered in the summary table. The ACCESS drawing function turns work instructions from the summary table for each manufacturing process into a work-instruction note and gives it to the production group.
Before using Micro Cadam, engineers had to generate the summary table and work-instruction note by hand.
While Nozuma doesn't need 3-D software now, Sony's Minoru Okuda, general manager of the systems planning department, says he "doesn't have time to design in 3-D."
Cut design time in half. Using Cadam and Micro Cadam, he has cut time to market for new televisions from 12 months to six months, and four of those six are for tool-making.
Sony produces about 500 new television designs per year, more than 60 of which are for the U.S. market. One of the features of Micro Cadam that helps speed up the process, Okuda says, is "Layers."
With that feature, engineers working on one part can call up on their screens the related parts other engineers are working on and overlay them on their own parts to check for clearances, such as proper alignment of drill holes -- all in real time. He says many 3-D systems would require engineers to file their work before another engineer could look at it, which would slow down the process.
Sony does use 3-D design for aesthetics. Enginers also send 2-D Micro Cadam files through an interface to SDRC's I-DEAS, PTC's Mechanica, MSC/ NASTRAN, Marc, and Abaqus for analysis. Next goal: Cut design to four months.
ATM keypads resist vandals
Noche, UK--The advent of ATM machines and other point-of-sale devices has made life easier for both those businesses that supply them, including Germany's Siemens Nixdorf AG, and the customers who use them. It has also made these machines attractive targets for vandals.
In an effort to outmaneuver the latter, Lucas Control Systems Products' (LCSP) Duralith™ Man Machine Interface Products has designed a stainless-steel, vandal-resistant keypad. The stainless-steel surface of the keypad withstands harsh environments and also protects components from rusting. The stainless steel is brushed to increase its scratch resistance.
Adhesive layers cover the unit's membrane switches; an injection-molded rubber layer prevents contaminants, such as dust, cleaners, and moisture, from getting onto keyboard contacts. To keep the keypad from jamming, the LCSP team at the United Kingdom facility added a patented rubber material that allows the keypad to absorb more force. An optional heater prevents the keys from freezing in cold European climates.
'Toothbrush' redesign scores globally
Ft. Collins, CO --To sell quality oral health-care devices worldwide, a company must take into consideration the many facets of the worldwide consumer. That's exactly what Teledyne Water Pik did in redesigning the subgingival irrigation attachment for the popular Pik Pocket®.
"It's part of an international product line," says Harvey Benoit, manufacturing engineer at Teledyne Water Pick. Not only did the redesign meet requirements for recyclable batteries, but "it is smaller and narrower than the original product so that it can fit on bathroom shelves in countries like Japan, where shelf space is very limited," Benoit adds.
Processing played an equally important role in the redesign. The company selected the Emabond® electromagnetic welding system from Ashland Chemical, Columbus, OH, to weld the polycarbonate jet-tip blank and knob together.
Design drives thermostat to market in weeks
Sherbrooke, Quebec--Facing formidable competition from around the world, C-MAC Industries Inc. turned to concurrent engineering to win a contract for a new thermostat slated to be installed in millions of Quebec households. The Iso-Therm® 3000 wall-mounted unit, produced for Hydro-Quebec, is expected to cut home heating power use in the province by up to 12%.
When C-MAC entered the competition, other manufacturers already had pre-production samples ready based on earlier thermostats. Their advantage didn't last, however: C-MAC and its project partners took their thermostat design from art to part in just 12 weeks.
GID Design, a Sainte-Foy, Quebec, design firm, detailed the injection-molded components and cast-aluminum heat sink for the thermostat. C-MAC and GID also used design-for-manufacturing-and-assembly (DFMA) to speed the design. The design duo's work resulted in a thermostat that was not only competitively priced, but met stringent quality and reliability requirements.
A third factor in the success of the Iso-Therm 3000 project involved GID's decision to mold the thermostat's entire casing of rigid vinyl supplied by the Geon Co., Cleveland, OH. Besides costing less than other engineering resins considered, Geon® HTX 6215 vinyl provided toughness to withstand installation, dimensional stability to ensure years of precision in regulating temperatures, lasting color, attractive texture for wall mounting, and inherent flame-retardance.
Vinyl also exhibited a processing versatility important for the success of the Iso-Therm 3000 project due to the complexity of the plastic parts. "C-MAC told us that assembly would be a driver in the finished cost of this product," says GID's plastics specialist Aldo Balatti.
Experienced in DFMA analysis, Balatti worked out an Iso-Therm 3000 design that consolidated functions into a few parts: 4.75-inch-square rigid vinyl housing components (top casing, bottom casing, and cover bezel) with a combined weight of 6 ounces, acrylic viewing lens, liquid-crystal diode, printed-circuit board, heat sink, and heat sensor or thermistor.
Taking advantage of vinyl's design freedom, Balatti built in these parts-consolidating features:
Snap-fits. The heat-sink, LCD, lens, and cover bezel all snap into place.
Integrated structures. A wall running the width of each casing serves as a reinforcing rib and isolates the heat sink so that heat is dissipated only through molded-in vents. Similarly, thermistor chambers molded into the casing interlock upon assembly, isolating the room-temperature sensor from internal heat.
Cost savings proved significant. Combined with the savings from use of relatively inexpensive vinyl, C-MAC reduced the price of the thermostat by 5%, estimates C-MAC R&D Project Manager Serge Beaudoin.
He and everyone else involved in the winning project agree that the key to success was the close working relationship among all parties: OEM, designer, toolmaker, molder, and resin supplier.
European 'smart cards' have a green theme
The Hague, Netherlands--The familiar plastic credit card has developed into the "smart card." It can adapt to incorporate such protective devices as laser engraving, a photo of the card owner, and computer chips. What several of these cards have in common, at least in Europe, is that they are produced with a copolyester material that is environmentally clean.
Credit-card makers Gieseke & Devrient Gmbh, Pintoplast AG, Trueb Druck, and Orell Fuesli selected the copolyester, EASTAR PETG from Eastman Chemical Co., Kingsport, TN, for the new "e-" or ecological-card. The first application: health insurance member identification in the German Federal Republic.
The copolyester thermoplastic polymer has excellent gloss and clarity. Cards made from this material can be colored, transparent, translucent, or opaque. And the material provides opportunities for source reduction because of its lower density when compared to many alternative materials.
The low-density PETG cards also weigh 8.3% less than PVC cards. Moreover, lamination cycle times in Europe have been reported to be 30% faster for PETG than for PVC cards.
Equally important, as these cards increase in number, each card can be recycled where such facilities are available. In the case of incineration, they will burn without producing noxious fumes or gasses. And, because the cards do not have small molecules that could leach into ground water, they are also safe for landfills.
Other users of the PETG card include BT (formerly British Telecom) in Britain for its Quick Reference Cards, and Swatch® in Germany for a beeper number card. Micros Bank, many Swiss cantonal banks, Credit Suisse, and the Swiss Bank Corp. employ the copolyester for their customer cards. In addition, several engineering companies use the "green" card for programming process control equipment.
Nylon cuts the metal from the pedal
Mount Olive, NJ--The 1995 Fiat Ducato features a pedal module that consists of a bracket, clutch pedal, and accelerator pedal, all made of glass-fiber-reinforced nylon; and a brake pedal and shaft made of steel. Not only does the lightweight module permit quick, easy assembly; it costs less to make than previous assemblies.
The spring-loaded brake and clutch pedals fasten to a steel shaft in the bracket. The accelerator pedal attaches to the housing with a steel pin. Cables connect to the pedals. Two force-fit brass bolts and four force-fit brass inserts mount the pedal module to the vehicle.
Weight reduction is significant. The new pedal module weighs in at only 6 pounds--about half of a typical metal assembly.
Parts consolidation also benefited from the new design. The pedal module's three injection-molded parts replace numerous steel components, all of which required assembly and welding. The nonarticulating accelerator pedal is a one-piece molding, while the nonarticulating clutch pedal has just two parts: a pedal pad and the pedal. In comparison, the brake pedal consists of six parts, including three weldments, a mechanical pin insert, and a snap-fit pedal pad. All the components fit into a single-piece housing.
Functionally, the new pedal module fulfills the requirements that previously have been dominated by steel. The nylon pedal resists deflection under high pedal loads (up to 340 pounds for the clutch pedal), and has the required creep resistance. Further, the lubricity of the nylon parts helps assure their smooth, unhindered operation without any other lubrication to assist.
The switch to nylon and the use of fewer components also lowered production costs. The parts, made from Ultramid® nylon supplied by BASF, do not require assembly. They also eliminate the need for corrosion-resistant coatings. The module costs about 20% less than a metal assembly.
Alloy improves machining productivity
Forest City, NC--By replacing a cold-finished aluminum alloy with one that is stronger and produces smaller machining chips, the Hydraulic Division of Parker Hannifin saved time and also saved money producing hydraulic valve blocks.
Central Steel and Wire Co., Alcoa's Wire, Rod & Bar Division, introduced 6013-T8 cold-finished aluminum to Parker Hannifin.
Alcoa's 6013-T8 cold-finished aluminum produces smaller and more easily broken machining chips than those produced from 6061-T6511 extruded aluminum. In addition, the strength of 6013-T8 cold-finished aluminum is about 50% higher than 6061-T6511. The anodizing performance and corrosion resistance of 6013-T8 is similar to 6061-T6511 material. And, 6013-T8 cold-finished aluminum has tighter tolerances than any extruded aluminum alloy, according to the maker.
Parker Hannifin performed a machining evaluation using 6013-T8 cold-finished aluminum. They ran two different production lots totaling 550 pieces of a 4.0 inch square x 7.25 inch long valve block. Due to the improved chipping characteristics of 6013-T8 cold-finished aluminum, Parker Hannifin engineers were able to increase the machining speeds and feed rates. And, since 6013-T8 chips did not pack the machine tools, machinists did not spend excess time monitoring the machining operation.
|Straightness (in./12 ft)
|Twist (in./12 ft.)
| In hydraulic applications, Alcoa 6013-T8
performance allows for the higher operating
pressures typical of steel and cast iron.
Machining and deburring productivity results for these production lots were compared with the historical data for 6061-T6511 extruded aluminium. By switching to 6013-T8 cold-finished aluminum, Parker Hannifin realized a machining productivity improvement of 15 to 25% over 6061-T6511 extruded aluminum. The deburring productivity improvement achieved through the use of 6013-T8 cold-finished aluminum was 25-50% over 6061-T6511 material.
Based on the results of the evaluation, Parker Hannifin converted the majority of its in-house 6061-T6511 extruded aluminum applications to 6013-T8 cold-finished aluminum.
Software drives BMW/Rolls jet-engine effort
Dahlquist, GER--Engineers at BMW-Rolls Royce GmbH have used software to shave a year off the typical design time for aircraft jet engines.
The company, formed by the German and British car makers to develop a family of aero engines for large corporate air-craft and regional jets, delivered its first product--an up-to-23,000-lbs/thrust business jet engine--in 48 months. The industry average reportedly is 60 months. Engineers use Computervision's (Bedford, MA) CADDS®5 hybrid modeling software, Concurrent Assembly Mock-up (CAMU), and EDM (Enterprise Data Management).
"The hybrid modeler is compatible with all our test and analysis programs, as well as advanced modeling techniques from explicit geometry to dimension-driven solid modeling," says Chris Amoah, EDM project leader for the company.
Jim Broughton, application specialist at BMW/Rolls Royce, says the assembly mock-up software improves the quality of first-time designs and lets engineers work in parallel rather than serially. "Design and analysis engineers can work at the same time on the same designs," he says.
The resulting digital prototype is completely up to date all the time, he says, unlike a physical prototype that's simply a snapshot in time.
Beyond CAD, engineering managers at the joint venture had to wrestle with how to coordinate design efforts emanating from two countries, Germany and the United Kingdom. He says they use EDM to track and manage CADDS 5 data and non-CADDS-5 data. Additionally, he asserts, custom extensions of EDM allow engineers to transfer large data files to and from Belfast-based Shorts Brothers, a supplier of engine-support equipment, in under 30 minutes.
Washer features fuzzy logic, virtual sensors
Fabriano, Italy--Engineers at Merloni Elettrodomestici are using fuzzy-logic microcontrollers and software-based "virtual" systems to design household appliances that eliminate most human decision-making from domestic chores.
While the use of neurofuzzy logic in appliances isn't new, Merloni is one of the first to use the technology to control appliances completely rather than partially. The Ariston Dialogic washing machine, for example, only requires the user to set one parameter on the panel switch: the most delicate item to be washed.
"Fuzzy logic is particularly suited to the qualitative description of complex systems, such as washing machines, which cannot be modeled mathematically," says Valerio Aisa, Merloni's head of electronics. "It also allows us to use inexpensive sensors."
The washing machine evaluates the quantity and type of washing--heavy cotton or light synthetics--using a virtual sensor that measures the speed with which water is absorbed. The time needed to initially fill the machine with water varies according to washing type, but is independent of the quantity of clothes. As the wash progresses and clothes absorb more water, the water level is automatically topped up by a traditional hydrostat-operated water valve. The greater the quantity of washing, the longer it takes to top up.
The Merloni system measures the times for the initial fill and successive top-ups. "Fuzzy" rules derived from more than 12 months of empirical tests then help determine washing quantity and type.
The wide range of water conductivities found during the various wash-cycle phases made it difficult to measure conductivity directly with a linear sensor. Instead, the resistance of the water is used to discharge a capacitor; and the time taken, which varies from 500 microseconds to 2 seconds, is measured and compared with five fuzzy bands to determine the degree of hardness--very hard, hard, average, soft, or very soft.
Based on information gathered from various real and virtual sensors as well as embedded rules, an 8-bit microcontroller from National Semiconductor automatically sets the correct spin speed and energy for washing, rinsing, and spin cycles.
If a sensor breaks, the system defaults to average-wash data.
A similar combination of neurofuzzy controllers and virtual sensors has been used for companion dishwasher and refrigerator models in the Ariston Dialogic line, scheduled for sale in Europe the second half of 1995.