Engineering News 7650Engineering News 7650

Beyond brake control

Adaptive cruise control maintains a safe distance between moving vehicles

Karen Auguston Field

Boxberg, Germany--In the 1970s, engineers at Robert Bosch delivered the first electronically controlled, anti-lock braking system (ABS) specifically designed for production cars. Building upon ABS technology, the company later introduced traction control followed by its electronics stability program (ESP).

What's next on the agenda? Adaptive cruise control (ACC), says Wolf-Dieter Jonner, Bosch's director of applications and system development. Planned for series production next year, ACC represents the latest development in the quest to control vehicle motion electronically.

Adaptive cruise control uses all of ESP's sensors to monitor vehicle movement and promote brake control. But it goes a step beyond with the inclusion of a mm-wave radar sensor with integrated signal processor and control unit. Installed at the front of the car, the radar sensor detects the relative speed and distance of vehicles driving ahead.

To guarantee reliable sensing of objects, particularly in low visibility conditions, the radar sensor operates in the 76.5-GHz frequency range. Sensing distance is between 2 and 120 m for an ultimate sensing angle of 10 degrees , and frequency modulation brings distance/velocity accuracies to within 1 m and 0.5 m/sec.

The radar sensor's digital signal processor supplies information on distance, relative speed, and angle of multiple leading vehicles to the control unit. Based on additional information (yaw rate, lateral acceleration, wheel speed) received from ESP sensors via CAN-Bus, the control unit computes the acceleration or deceleration necessary to maintain the prescribed following distance. Other engine ECUs manage the appropriate actuator systems.

During operation, the control unit updates target vehicle speed at a frequency of 10 times per second. The driver, of course, may intervene at any time to override the ACC.

Taking electronic vehicle control to this new level involved some unique challenges for Bosch engineers. For example, while straight stretches of road pose no difficulties for course prediction, curves do. Solving this problem required a combination of methods that involve measuring the relative difference of wheel rpms, lateral acceleration, and yaw rate. Since the lateral position or the angle relative to the longitudinal access is also important in identifying the correct leading vehicle, the radar sensor uses a three-beam antenna that achieves an angular resolution of better than one degree.

As for the future, Bosch is already working on an enhanced version of ACC for city driving, which will require a wider, close-range monitoring zone and better means of distinguishing between standing barriers such as idling cars and telephone poles.

These systems spell vehicle motion control

ABS--Antilock Braking Systems prevent a vehicle's wheels from locking up by electronically controlling individual wheel brake pressures.

TCS--As with ABS, Bosch's Traction Control System uses passive or dynamic rotational-speed sensors to monitor the wheel speeds. Only it works much like the inverse of ABS. If a sensor detects an unusually high rpm on a wheel, the TCS either automatically brakes the spinning wheel via hydraulic pressure modulator, or it reduces the drive torque.

ESP--The Bosch Electronic Stability Program, like ABS and TCS, stabilizes a vehicle in the longitudinal direction. But it also prevents the lateral forces acting on the car from breaking away. When the system detects an impending slip, it applies braking forces to the appropriate wheels and regulates engine torque.

Industry eyes dual-voltage system

Every time automakers add a new electronic feature on a car--headlight wipers, for example--a little more of the total power budget gets used up. Researchers predict that advanced electrical systems such as electromechanical valve actuators and active suspensions will triple the power demand of some cars in the future.

The 12V dc battery in today's cars won't handle such demands. At least that is the consensus of a group of engineers from auto companies and auto equipment suppliers that are members of the Massachusetts Institute of Technology Consortium on Advanced Automotive Electrical/Electronic Components and Systems.

Their proposal: a 42/14V dual-voltage electrical system architecture. Targeted initially for luxury cars sometime between 2005 and 2015, the dual-voltage system is designed to separate out high-power loads. The main benefits of having a higher voltage system are reduced current and improved efficiency in energy generation and distribution.

Much uncertainty surrounds what the ultimate electrical system of the future will be and when it will be introduced. But whatever the final outcome, it will have a major impact on companies like Robert Bosch. That's why the company is backing the 42/14V dual-voltage concept. "Our strategy is to take an active role in this discussion," says Robert Oswald, member of business management of Robert Bosch GmbH.

More information on the 42/14 dual-voltage system can be found at the consortium's web site: web.mit.edu/consortia/auto-consortium/

Laminated glazing adds security to BMW windows

Reflecting a desire for greater security, drivers of BMW 7-series cars can now choose side windows made from an impact-resistant glazing that incorporates a polycarbonate sheet. The Lexan(R) ULG 1000 optical sheet, supplied by GE Structured Products (Pittsfield, MA), consists of a thin layer of polycarbonate surrounded by a thin layer of glass on each side. In all, the glazing includes six layers laminated into a 9-mm-thick material that also features two layers of security film and an anti-lacerative coating. The result, according to GE engineers: a security glazing that's virtually impenetrable to carjackers and thieves, while still providing the needed level of optical clarity. The windows are now available in Europe and the U.S.

Mini-shot basketball set goes poolside

Ormond Beach, FL--Pool Shot Products Inc. sales skyrocketed when its "breakthrough" pool shot swimming pool basketball set made the pages of Sports Illustrated's swimsuit issue and appeared on MTV's Spring Break Party. The patented plastic units feature an oversize winged backboard that returns both scoring and errant shots back to the pool.

In spite of the set's success, Pool Shot had a problem. The unit's large awkward size, which required shipping and residential delivery by an 18-wheeler tractor trailer, and its $600 price tag proved too steep for many pool owners.

What Pool Shot needed was a smaller version with a reduced price that could be shipped by UPS. Greg Graham, Pool Shot president, turned to engineers at Meese Orbitron Dunne (MOD) Co. (Ashtabula, OH), a rotomolder with design and production experience on similar projects, for help.

In less than six months, MOD engineers responded with the mini pool shot. Reduced in volume by 61% (601/2 3 53 3 48 inches to 39 3 32 3 36 inches), and in weight by 43% (96 to 55 lb), the mini pool shot ships by UPS in a single carton. To make this possible, MOD engineers replaced the primary backboard support pole, which measured nearly 3 ft in length, with a two-piece, self-supporting, sliding unit that slips easily into the single carton and an existing support base.

For deckside portability, anti-tip stability, and added safety, the plastic support base is filled with water so that it weighs more than 400 lb. The entire backboard, support system, and base are rotomolded from Mobil and Phillips Chemical UV-treated, linear, low-density polyethylene (LLDPE) resin (supplied by Channel Polymers; Norwalk, CT). The material eliminates the potential for rust and cracking due to sunlight, while assuring longevity under severe outdoor conditions. In fact, the set can remain at poolside all year and sells for $395.

Sailboat features 'indestructible' hull

East Lyme, CT--For 40 years or more, fiberglass has served as the major material for sailboat decks and hulls. That tradition is about to change, thanks to a new, patented advanced composite process (ACP) perfected by JYSailboats Inc. in the manufacture of its JY15 (15-ft) competition-class sailboats.

The thermoforming-based process incorporates a vacuum-formed outer skin, reinforced by a central foam core, with added support via an inner bi-directional cloth. The tough, high-gloss skin consists of a co-extruded sheet of Luran(R) S ASA (acrylic-styrene-acrylonitrile) and Terluran(R) ABS (acrylonitrile-butadiene-styrene), both supplied by BASF Plastics (Mount Olive, NJ). The result: a UV-resistant hull said to be five times more impact-resistant than fiberglass that can withstand long-term use and exposure to the elements and ACP is a clean, closed process; even scrap can be recycled.

Of equal importance to JYSailboats was the fact that ACP is an automated process that produces virtually identical hulls. In contrast, fiberglass lay-up construction tends to be very labor-intensive, with the end product not always a replica of the original. And, to produce a JY boat takes about 14 manhours; a fiberglass counterpart requires 48 manhours.

JY stands for Johnstone Yachts. It gets its name from Rod Johnstone, a designer of many J-class sailboats. Looking at available boats on the market, Johnstone saw most were too complicated, with lines and cleats all over, spinnakers, and pole launchers--and all the designs had been around for more than 25 years. The Laser was great, if you wanted to sail by yourself, but for the husband/wife or parent/child team there was nothing new that fit today's lifestyle.

Johnstone sketched out a design, got some materials, and with friends and family built a boat in his garage. When it could float, he took it sailing and got everyone he could to take a spin. He listened to their comments, took it back to the garage, and, after six months, the boat was ready to go. Christened the JY15, the boat measured 15-ft long and weighed only 275 lb. The hull, a planing design, was self-bailing, which meant it was safe and stayed dry.

Best of all, the JY15 was simple and easy to sail. She didn't have lots of cleats and a million lines. Controls were easy: just main and jib sheets, main and jib halyards, boom vang, and outhaul, all perfectly balanced.

What remained to be decided was the best way to build the boat--fiberglass or the new, high-tech plastic composite construction. When Johnstone totaled up all the advantages of APC, the decision was simple. He notes that in addition to all its other benefits, APC also results in a stronger hull that requires almost no maintenance and is easy to repair. There are now 2,300 JY15s sailing worldwide.

Just how sailworthy are the advantages of ACP? Hunter Marine Corp. (Alachua, FL), a leader in sailing innovation for more than 25 years, has contracted JYSailboats to produce many of its most popular models.

Thermoplastic gives Boxster greater precision

Ludwigsburg, Germany--Porsche AG's Boxster features a highly engineered gear and select-shift cable designed to provide precision push-and-pull movements from the driver's gear lever to the five-speed manual gearbox. A thermoplastic rubber helps give the system maximum control.

In developing the application, system supplier VOFA GmbH & CoKG (Dusseldorf, Germany) part of the DURA Group, replaced various thermoset rubber parts with a 55 Shore A grade of thermoplastic elastomer (TPE). Advanced Elastomers Systems (AES) (Akron, OH) supplied the material.

"Santoprene rubber was selected for its excellent elastic properties over a broad temperature range due to its fully cross-linked rubber phase," says Juergen Gloeckler, automotive director, Europe, AES. "The TPE also allows individual parts of the gear and select shift systems to be produced using standard thermoplastic processing techniques, resulting in lower per-part costs and individual part-design and system integration."

Designed and developed by Porsche engineers in just three-and-one-half years, the two-seat Boxster has become a trendsetter in the open-top sports-car market for its performance, maintenance, safety, and convenience features. Moreover, the Santoprene parts give the vehicle an added advantage. All are fully recyclable, unlike the thermoset rubber components they replaced.

CAD companies compete computer-to-computer

Laurie Ann Peach, Associate Editor

Detroit, MI--A cloud of tension hung over the room, as everyone anxiously awaited the start of the first-time-ever CAD Challenge at this year's Computer Technology Solutions/Autofact show.

Jeff Rowe, publisher of Zero/One, a news letter for industrial designers, along with the Society of Manufacturing Engineers and Stephen Wolfe from CAD/CAM Report, organized and facilitated the event. Sponsors invited 14 CAD companies to pit their CAD software against the competition in a timed trial. In the end, only five companies accepted--Ashlar (Vellum Solids), BayState Technologies (CADKEY and FastSurf), SDRC (I-DEAS Artisan Series), Dassault (SolidWorks), and Unigraphics Solution (Solid Edge).

The challenge: Generate from scratch a 3D model of an automotive exterior mirror assembly consisting of four parts.

After creating the models, organizers gave each three-person team several design changes, such as modified dimensions. One hard and fast rule: Participants could use only off-the-shelf software--nothing in beta test.

Two people from each team worked simultaneously at keyboards modeling the parts, while a third person explained to the audience what was happening. Five judges recorded how long it took each team to finish specific steps.

While the judges watched the clock, the audience (about 40 people) graded the software packages on seven key features: from sketching ability to best overall for mechanical solid modeling.

The audience consisted of anyone that registered for the session, from end users to CAD developers. However, vendors were prohibited from voting.

Based on time alone, Solid Edge from Unigraphics was the clear winner, finishing in 94 minutes. Based on popular audience vote, SolidWorks was awarded the CAD challenge trophy

In concept, the CAD challenge was a novel and bold undertaking--essentially asking CAD companies to back up their claims (see "Your Guide to Mid-Range CAD," Design News, 9/21/98, pg. 91) in front of end-users and the competition.

In practice, a few bugs needed ironing out. Perhaps the biggest disparity was that the audience could only view one company's progress at a time on a large screen in the middle of the room. This left little opportunity to do a fair comparison between software packages. Nor could the audience accurately gauge each group's progress.

In the end, the contest was a good illustration of the difficulties inherent in setting up any comparison of software capabilities. Does the speed of a CAD system necessarily make it "better" than any other? No. CADKEY, for example, though they did not finish first, took great pains to determine if each part was manufacturable before declaring they were finished. "Time is only one measure of a good CAD system and not necessarily the best one," says Rowe, "but it was the only quantifiable criteria."

Neither is presentation nor salesmanship a good competitive criteria, which is primarily what the audience had to base their vote upon.

A CAD solution should depend on the needs of the company. Do company requirements dictate an easy-to-use workhorse, or a "fast," but perhaps more complicated, solution?

All the companies that dared to participate in the competition deserve applause. And each has its place on the CAD market.

I, for one, would enjoy seeing such a contest repeated. However, I would like to see one with a wider range of players in a more controlled, leveled environment.

Colorable compounds keep power cords strong, resilient

Pawtucket, RI--Add colorful power cords to the reasons a customer might buy a new appliance. That's the theory behind Teknor Apex's introduction of new thermoplastic elastomer (TPE) compounds for extruded power-cord insulation and jacketing, as well as injection-molded plugs. The new materials are said to provide more flexibility at temperature extremes, higher levels of chemical resistance, and greater colorability than conventional polyvinyl chloride (PVC) elastomers.

Designated the Elexar(R) Super Flex^TM (SF) Series, the TPEs can be pigmented in brighter and more vivid colors that are achievable with PVC elastomers, according to Donald G. Ouellette, Teknor Apex's industry manager, wire and cable compounds.

"Manufacturers of products ranging from appliances to lawn and garden tools can now improve the end-use performance of flexible cords, while simultaneously boosting product appeal," Ouellette notes. In addition to greater flexibility over a wide temperature range, he adds, Elexar SF compounds provide better resistance to fuel, oils, and other aggressive substances than PVC elastomers.

To back up his statements, Teknor Apex commissioned an independent laboratory to quantify the retained flexural modulus of molded test plaques over a -60 to 100C range. "The test results indicate that Elexar SF products will provide far greater flexibility in end-uses, especially after exposure to elevated or subzero temperatures," Quellette explains. "This is an especially important advantage for flexible power cords used on outdoor electrical equipment."

Elexar Super Flex products currently available in commercial quantities include:

Elexar SF 8431 and 8451 insulation compounds. These provide Shore A Hardnesses of 70 and 85, tensile strength values of 2,500 and 2,250 psi, and ultimate elongation values of 680 and 650, respectively. Both exhibit a brittle point of -60C and limiting oxygen index (LOI) of 18.0.

"Beside cutting concentrate costs, the colorability of Elexar SF products enables developers of new appliances to place more emphasis on power and extension cords as design elements," says Ouellette. He cites cords pigmented to match brightly colored appliance housings or to stand out through the use of today's "hot" colors.

Non-conforming material-control process automated

Fort Worth, TX--Lockheed Martin Tactical Aircraft Systems has implemented an automated control process to streamline its procedure for documenting non-conforming material in the factory that produces the F-16 and major components for the F-22 and F-2 fighters.

Non-conforming material (usually referred to simply as non-conformances) consists of discrepant parts that fail to meet exact engineering specifications. Non-conformances are documented and carefully tracked to ensure that proper corrective action is taken.

In the past, documenting non-conformances involved a lengthy, time-consuming manual procedure that starts with a five-copy Quality Assurance Report (QAR) form. Once a non-conformance is identified by a quality assurance inspector, a QAR is initiated. Completing the entire process took from 20 to 30 days.

Enter the new process, based on off-the-shelf workflow software from Action Technologies (Alameda, CA) and an in-house graphics interface. It streamlines seven steps into four.

The Quality Assurance Inspector enters the QAR directly into the PAAC data management system via computer. It is reviewed by personnel who enter the QAR disposition into the system, which automatically performs transactions and creates rework or repair orders based on the disposition. A laser-printed paper QAR copy is routed with parts, and then sent to the Quality Assurance Inspector, who closes the QAR.

The automated system cuts up to 10 days from the cycle. It also eliminates a complex five-ply paper form, requires less administrative personnel, greatly improves data accuracy, and results in no lost QAR forms, plus the immediate recognition of non-conformance events.

Taking ER to the street

Rick DeMeis, Associate Editor

Los Angeles--It looks like a high-tech stretcher, but it's more like a portable emergency room (ER). What is it? Northrop Grumman gives it the medically sounding acronym LSTAT (Life Support for Trauma and Transport), see DN3/3/97, p. 141. And the U.S. Food and Drug Administration has given the company permission to market the portable trauma care system to boost the survivability of military and civilian trauma victims.

Northrop Grumman used its expertise in aerospace materials, information processing, and systems integration to come up with the LSTAT under the auspices of the Army (and its Walter Reed Institute of Research) and the Defense Advanced Research Projects Agency (DARPA). The Army, Air Force, and Marines are working with the company, testing and evaluating the system, and may establish plans for joint service use.

The 100-lb target weight LSTAT consists of a five-inch-thick carbon-composite platform structure to support the patient. Within this base are batteries in the event external power is not available. The unit also houses: oxygen; heart- and breathing-rate monitors; a defibrillator; a blood chemistry laboratory; a ventilator to assist in breathing; a suction pump to clear airways or the abdomen; and an infusion pump to deliver fluids and administer drugs. Northrop Grumman is not disclosing its systems suppliers at this time.

A data recorder on the LSTAT also logs the patient's lifesigns during the trauma incident. This information can be data-linked ahead to a care center to prepare for a victim in transit. The system's LCD display allows relief personnel to more easily scan and monitor functions of several patients at one field site.

LSTAT military applications are obviously in battlefield wounded rescue and care. The device could see civilian use in search and rescue, disaster relief, and critical-care transport.

Lubrication system keeps high-speed presses running smooth

Warwick, RI--At the Engineered Products Div. of high-speed metal stamping company ETCO Inc., consistent lubrication is critical for meeting quality and production requirements--especially when stock is feeding into their 10 Bruderer presses at 60 to 70 ft/min.

ETCO stamps electrical terminals out of brass, steel, beryllium copper, and other alloys, and also manufactures the equipment used to crimp them to the wires. Press speeds range from 600 to 1,800 strokes/min.

"At our high press speeds, tooling heats up very quickly," explains Second-Shift Supervisor George Brennan. "If we don't apply the correct amount of lubricant, it's very easy to break a punch or pull a pilot, and we also have to spend more time on sharpening. Maintenance for just one tool can cost anywhere from one to four hours of lost production time."

EFD's (East Providence, RI) MicroCoat(R) lubrication system provides the consistent lubrication required. It has helped reduce downtime, improve the quality of finished parts, and extend the interval between die sharpenings on each of the 10 Bruderer presses by 500,000 strokes. The system is pneumatically operated and composed of spray valves, a controller, and lubricant reservoir.

The MC785 precision spray valve measures 2.5 inches high and is installed inside the press between the feed and die. It uses low-volume low-pressure (LVLP) air to apply lubricant in fine, even films without waste, mist, or overspray. Each system supports up to four valves, mounted above, below, or above and below the stock.

For its application, ETCO mounted two valves above the stock and two below. For stock between 2- and 4-inches wide all four valves are on; when stock width is 2 inches or less, two of the valves are turned off. The MC4000 controller has individual flow controls that allow each valve's coverage to be adjusted independently.

Film thickness can be increased or decreased instantly, so optimal coverage is established in less than 1 min and maintained for the duration of the run. This helped ETCO as the company stocks more than 40 different metals in a variety of widths and thicknesses.

Because the controller is tied-in to the press controls, lubrication begins automatically when the press is turned on and stops when it shuts down. And, if the air pressure to the controller or the lubricant in the tank drops below a preset level, the MC4000 automatically stops the press before tooling damage.

Lubricant is supplied from a 1-gal MC685 acrylic see-through reservoir, which minimizes refilling, prevents contamination, and allows the operator to visually monitor the oil level.

ETCO has installed the MicroCoat system on all 10 of its presses. "Now that we can control the amount of oil," says Maintenance Supervisor Rolland Blom, "we just start out with each valve's flow control set at one, observe the results, and fine-tune the coverage to exactly where we want it--without stopping the press. Being able to achieve consistent lubrication lets us go an extra 500,000 strokes between sharpenings on each press, with much less tool damage."

Cleaning, waste, and disposal issues have also decreased. Previous systems sometimes produced as many as 10 drums of sludge a month; the MicroCoat system yields around one. As a result, Brennan noted that ETCO is saving a few thousand dollars a year.

"The MicroCoat system has increased our die life by 50%," says VP of Mfg. Dennis Herdegen. "The longer interval between sharpenings, combined with less maintenance and downtime, has given us more production capacity. And part consistency is dramatically better."

CAM prototype confirms art of design

Warren, RI--When asked to help TPI create the body for a new line of transit buses, Anderson Design (Plainville, CT) turned to CAM software and CNC rapid prototyping. Although Anderson Design usually supplies its designs as CAD files, they needed to supply TPI with full-scale DXF files for CNC machining. Using this data, TPI would loft the files to create pattern sections for assembly into a full-body mold.

Engineers at Anderson Design worked within the requirements for the chassis and engine and approximate dimensions to develop a series of concept sketches. Designers then hand-sculpted several iterations of 3D scale models in soft foam. The most-liked one was then sculpted as a hard-foam model at 1:20 scale.

After approval, Anderson engineers typically build 3D geometry in Pro/ENGINEER using dimensions from the hard-foam model. Since irregular surfaces required blended tangencies, engineers felt the chances of recreating the model were less than good.

"The Pro/ENGINEER 3D file can be viewed and rotated," says Joe Paul, a project engineer at Anderson Design, "but the view was not sufficiently detailed and it was difficult to tell what was smooth and/or aesthetically correct."

To ensure accuracy of TPI's final work, Anderson Design used Mastercam from CNC Software (Tolland, CT) and CNC machining to create a realistic model from the Pro/ENGINEER surface documentation data. "Only a certain amount of detail can be included when hand-modeling," says Project Leader Dave Kaiser. "We want an accurate model of intricate, precision-driven pieces. Using Mastercam and CNC is the only way to do that."

To create the model, programmer Bill Hester imported Pro/ENGINEER files in IGES format into Mastercam and generated the toolpath. Then he ran it through Mastercam's solid-model toolpath verification to create an on-screen, as-machined model. This also confirmed the toolpath results.

For the finish pass, Hester used the same set of surfaces and a 0.25-inch ball end mill to tighten the stepover to between 0.007 and 0.015 inch. "This gave me a clean surface for engineering to review," says Hester. "Then it was simple to select the surfaces that needed to be machined further and create a toolpath with a 0.062-inch cutter. "

Both toolpaths were sent through verification again before sending code to the CNC machine which cut soft-foam comparison models for testing the geometry.

TPI's Project Manager Stephen Misencik received the Mastercam-prototyped Pro/ENGINEER files in DXF and IGES files as horizontal and vertical cross sections. He then plotted the sections full-size on an HP plotter.

"This was the easy part of the bus," recalls Misencik. "We just took it to a 3-axis CNC machine and let it cut the patterns out of 3/4-inch plywood, including grooves to allow the horizontal and vertical stations to fit together." Standing the vertical stations in order produced the 2D bus profile. Misencik says the front and back of the bus were more complex because of the compound curvature, so he used IGES files to maintain accuracy.

With the horizontal stations mated to their counterparts and the front and back sections bolted on, the bus was now in its 3D wireframe stage, accurate to within 1 mm. Surface dimensions were offset during pattern making to allow for the thickness of two 3/8-inch super-flexible surfaces to be laid over the wireframe.

TPI then added the details by hand--style lines, wheel wells, bumper recesses, door locations, window pillars, and headlight recesses. Again, Anderson Design provided TPI with files for each.

To achieve dimensional accuracy for the complex headlight assembly, Mastercam software was used earlier than usual. The geometry documentation accompanying the assembly would be six weeks in coming, and Anderson Design's target date with TPI was six days away.

Anderson Design's Engineer Tim Van Leeuwen placed a touch probe in the CNC machine and seated the headlight assembly on the machine bed. Working backward through Mastercam, he generated a point cloud which, when fed back to Pro/ENGINEER, established the geometry for the headlight integration.

"Anderson Design has always gone the extra mile for us," says Misencik, "like this headlight solution. They give us every detail we may need to check during our fabrication process."