Engineering Productivity Kit - Electronics

Electronics tame airbag deployment

Newton, MA--No one will argue that airbags save lives and, in fact, have saved many more lives than they have taken.

The National Highway Traffic Safety Administration (NHTSA) estimates that airbags have saved more than 1,500 lives in the U.S. since 1987. However, the agency also says there have been 52 automobile airbag-related deaths since 1991. Of those killed, 32 have been children sitting in the passenger seat or strapped into a rear-facing child seat on the passenger side--against safety guidelines. Many of the other deaths involved small adults.

Siemens Automotive, Auburn Hills, MI, already has a system on the market to prevent deployment of a passenger-side airbag into a rear-facing child seat. Called BabySmart, it debuted on the Mercedes Benz 1997 SLK model in January. A specially equipped child seat, made by Britax and available through Mercedes Benz dealerships, is part of the system.

Designed jointly by Siemens and IEE USA, the system senses if a child safety seat is present and determines its orientation. If the seat faces the rear, the system automatically deactivates the passenger airbag and prevents it from inflating in a collision. The system also prevents airbags from deploying into an unoccupied seat, thus saving car owners the $1,500 to $2,500 airbag replacement cost.

The system works like this: A pressure-sensitive foil integrated in the passenger seat detects the presence of a passenger. Similarly, the child safety seat detectors are integrated into the seat. They detect the presence of two resonators affixed to the safety seat's base. The position of the resonators, with reference to the location of the antennae in the vehicle's passenger seat, determines whether the child seat is rear facing, forward facing, or out of position.

The U.S. is primed for this type of passive safety system, notes Siemens Automotive President George Perry, largely due to the increasing number of light trucks and two-door cars, where a back seat is not a reasonable option for parents transporting small children.

NEC, Itasca, IL, has a similar system scheduled to debut in 1999- or 2000-model-year cars.

The Passenger Sensing System controls airbag deployment based on who or what is in the passenger seat. Flexible antennae in the vehicle seats act as transmitters and receivers of low-level electric fields. By monitoring changes in the electric fields, the system measures the difference in strength between the signal sent and received due to "interference" from what is occupying the passenger seat--be it a teenager or a bag of groceries.

The end result is a system NEC says provides the best reaction in any crash situation. For example, the airbag can be made to deploy if the system identifies an adult passenger or a child in a front-facing child seat. But the airbag will not deploy if the passenger seat is unoccupied or if the system detects a child in a rear-facing child safety seat, eliminating potential airbag injury to the child.

The Passenger Sensing System works with all child safety seats without modification, and isn't affected by light, reflectivity, temperature, air conditioning, dust, or noise.

Customizing airbags. TRW has spent more than three years prototyping a system that senses an occupant's size and position to activate "smart restraints" during a crash. Company officials say the weight sensing part of the system should be in 1998-model-year cars, and the full system should be available the next year.

TRW's occupant-sensing modules use seat scales and web payout to determine an occupant's size, dash-mounted ultrasound sensors and seat track and angle sensors to figure out the person's position, and a buckle switch to see if the person is using the seat belt.

Sophisticated sensors also monitor change in vehicle speed and belt payout so a microprocessor can calculate crash severity. Taking all this data into account, the processor executes a proprietary program to adjust the occupant restraint system's response.

Microprocessor-controlled functions include: managing the volume of gas in the airbag as it deploys, pretensioning the seat belt to position the occupant, and preventing airbag deployment if no one occupies the seat. The combined response, say TRW officials, absorbs occupant body energy, reduces the load on the occupant's head and neck, and optimizes airbag protection.

The idea behind these systems is to make crash protection work for all car occupants--whether they're in a child safety seat or leaning forward to adjust the radio. The currently proposed airbag warning labels may serve only to cause drivers to permanently shut off their airbags.

--Julie Anne Schofield, Senior Editor

Turn your body into an antenna

Scientists at IBM's Al-maden Research Center, San Jose, CA, are perfecting Personal Area Network (PAN) technology that uses the natural electrical conductivity of the human body to transmit electronic data. Using a microcontroller-powered prototype transmitter--roughly the size of a deck of cards--and a slightly larger receiving device, the researchers can transmit a programmed electronic business card between two people via a simple handshake. What's more, the prototype allows data to be transmitted from sender to receiver through up to four touching bodies.

The body's natural salinity makes it an excellent conductor. PAN technology takes advantage of this conductivity by creating an external electric field that passes a billionth of an amp to carry data. Data speed is equivalent to that of a 2,400-baud modem.

Possible applications include: electronic business card exchange, exchanging data between communications devices and electronic smart cards, public phones with PAN sensors automatically reading a user's calling-card number and PIN, and health care workers identifying patients and their medical histories simply by touching them.

Reinforced nylon overcomes fuel-system ESD concerns

This month, Texas Instruments introduces what it claims is the world's most powerful digital signal processor (DSP). First in the new TMS320C6x family, the TMS320C6201 fixed-point 200-MHz processor delivers 1,600 MIPS (million instructions per second)--reportedly 10 times the performance of the highest-performing DSPs currently on the market, including those from TI. At $96, the chip offers a 50% lower DSP cost per channel in such applications as wireless base stations, remote-access servers, pooled modems, cable modems, voice-mail systems, and digital subscriber loop (xDSL) systems, according to company spokespeople.

Analysts say this DSP will radically shift the emphasis of designing systems from hardware to software. This should result in performance that will not only eliminate the Internet bottleneck, but could also be the springboard to "unplugged" applications, such as instantly sending voice or data to anyone from anywhere in the world. The technology could also make possible extreme personalization of electronics--keyless home access via voice and face recognition, for example.

In terms of traditional benchmarks, the 'C6201 can perform a 1,024-point complex FFT (fast Fourier transform) in 70 microseconds--10 times faster than competing DSPs. Development tools for both PCs and Sun workstations include an efficient C compiler, an assembly-language optimizer, and a Windows-based debugger interface. A hardware emulation board is also available.

Additional details...Texas Instruments, Semiconductor Group, SC-97001A, Literature Response Center, Box 172228, Denver, CO 80217. Phone (800) 477-8924, ext. 4500 or http://www.ti.com/sc/C6x.

Get custom microcontrollers in 7 days

Austin, TX--The world may have been created in six days, but if you wait an extra working day you can get an 8-bit Motorola 68HC08 built to your specifications. Previously, this work could take several months.

Motorola's CSIC (Customer Specified Integrated Circuits) division's 7-day program uses ready-made modules in the 68HC08 development library. Designs start with the 68HC08 core, and customers can add such modules as I/O structures, A/D converters, timers, display drivers, and various types of memory.

The design methodology also lets Motorola engineers simultaneously create design and technical documentation for the device, delivering a complete package to a customer within a week. Customers can even submit software code while the company fabricates the device, allowing for late ROM programming.

"This new streamlined design program will let companies significantly reduce product development cycles, helping them to respond quickly to market opportunities anywhere in the world," says Motorola's Charles Studor, project manager. The firm will release the design methodology to all Motorola worldwide design centers this year.

For more information about Motorola's 7-Day CSIC program: visit http://design-net.com/csic.

Application tips

Single connection handles power and communications

Capacitor-inspired design packs 1.2 Ah in a 2.1V, 2.9-oz cell

Julie Anne Schofield, Senior Editor

Wheat Ridge, CO--Batteries aren't very efficient. In fact, at high discharge rates, they typically utilize 5% or less of their active material.

This fact bothers many engineers, but Tristan Juergens decided to make a goal of improving a battery's active-material utilization under all loads. Achieving this goal would make possible smaller batteries that could do more useful work.

While working at an electronics company, he took apart an electrolytic capacitor and noted how it was made with a large surface area and extremely thin plates.

"Capacitors have very low energy density and therefore aren't useful as a power source," says Juergens. "But by combining the construction form of a capacitor with the technology of lead-acid electrochemistry, it is possible to provide high sustainable power."

After several years of product development, Juergens perfected his Thin Metal Film (TMF) technology in the form of the Bolder 9/5 subC cell. The 2.1V, 1.2-Ah cell measures 2.76 inches (70.1 mm) long and 0.90 inch (22.9 mm) in diameter. It weighs just 2.9 oz.

TMF technology employs two key structural innovations: very large plate surface through the use of extremely thin, closely spaced plates; and unique end connectors that provide a very-low-impedance connection between plates and the device to be powered.

To form the positive and negative plates, 2/1,000-inch-thick lead foil is coated on both sides with 3/1,000-inch-thick lead oxide. A strip along the edge of each plate is left uncoated. A glass-fiber layer separates the positive and negative plates, which are then wound together in what Juergens calls a "jellyroll" configuration.

The uncoated strips of each plate protrude slightly from opposite ends of the wound cell. Lead terminals cast onto each end of the cell provide an electrical connection for the entire exposed edge. Encapsulating the entire edge of each plate facilitates current flow, minimizing cell internal impedance, which maximizes power.

The thin foil plates and cast-on terminals enable the cell to surpass the performance of other batteries, including NiCd designs, say Bolder Technologies officials. Compared with various conventional technologies, the design increases the ratio of plate surface area to active material by 16 to 19 times, and decreases the length of the electron flow path by 20 to 80 times.

"We're still using conventional lead-acid chemistry--the normal lead-acid charge and discharge reactions occur--but the fundamental difference is that the plate thickness is between 10% and 1% of the thickness of conventional lead-acid cells," says Juergens. Decreasing the plate thickness increases the surface area for the same amount of active material.

Greater surface area is key, stresses Juergens, because it allows more of the active mass to participate in the charge/discharge reactions at higher and higher rates. Another result, the company claims, is that users can charge the battery in five minutes.

In addition to the traditional lead-acid battery benefits of reliability, low cost, and long life, the Bolder cell also provides:

- Very fast discharge and recharge.
- Flat voltage profile.
- No memory effect.
- Cool operation.

Applications for the Bolder cell include: cordless power tools, backup power supplies, engine starting, hybrid electric vehicles, battery-powered toys, cellular phones, portable computers, grass trimmers, and patient-monitoring equipment.

Chrysler Corp. has said it will use 600 Bolder cells in its Dodge Intrepid ESX concept car, a prototype diesel-electric vehicle. Another company, Boulder Laser Systems, says it is designing the batteries into portable cordless laser welders.

Additional details...Contact Arnie Allen, Bolder Technologies Corp., 5181 Ward Rd., Wheat Ridge, CO 80033, (303) 422-8200.

Application tips

Thin-metal-film battery maximizes power density

Tom Rosenberg, INTERBUS System Group Engineer, Phoenix Contact Inc., Harrisburg, PA

PowerCom^TM connection technology is power and communications in a single connection. It enables device communications using the power supply connection in just three easy steps. Non-polarized, watertight IDC connectors provide error-free termination, lowering sensor and actuator connection costs for an I/O network.

INTERBUS Loop and PowerCom, using QuickOn^TM connectors, are based on the industry-proven INTERBUS-S networking technology. INTERBUS Loop provides a single protocol solution for both device- and sensor-level I/O networking. Generation 4 INTERBUS-S systems can incorporate the IN-TERBUS Loop products directly into your existing application. Sharing the same protocol enables seamless integration between a device bus and a sensor bus. This creates a distributed I/O network that works and reacts as a single network.

This tight integration of INTERBUS Loop with INTERBUS-S takes advantage of the best of both bus types: device and sensor.

The loop network forms a medium to transmit a full-duplex signal for optimum speed while carrying the 24V dc power to the I/O devices. Fast, simple, single connectivity for both power and communications using a proven bus protocol makes the PowerCom, INTERBUS Loop, and QuickOn connectors a powerful tool for manufacturing and process-control applications.

To speak with a Phoenix Contact INTERBUS systems group engineer, call (800) 586-5535.