Chicago — It will take new types of processors and a better breed of sensors to meet the demands of a proposed National Highway Traffic Safety Administration standard that addresses side-impact car crashes. Manufacturers of automotive devices anticipate selling tens of millions of additional MEMS-type accelerometers and pressure sensors down the road if the regulation is enacted. But they will first face a substantial computing problem as automakers begin installing side airbags in millions of new cars.

The NHTSA's first update in side-crash standards in 14 years opens the door to an extra 50 million to 70 million unit shipments of sensors a year by 2009, when all new vehicles would be expected to comply, experts estimated. Side airbags — which observers see as the most likely route for fulfilling the mandate — would demand anywhere from two to six additional silicon sensors per vehicle. Microcontrollers, ASICs and digital signal processors would also be needed, along with new data buses.

Ultimately, electronics suppliers expect European and Japanese automakers to employ side bags across their entire product lines, as well. Indeed, many European vehicles already have them.

"The majority of vehicles around the world will be using side airbags and satellite sensors," said Dave Zawadzki, product manager for accelerometers at the Micromachined Product Division of Analog Devices Inc. (Cambridge, Mass.), referring to accelerometers that reside a few feet from the central airbag module.

Automotive supplier engineers say the NHTSA standard will call on carmakers to meet one new test and one existing one for two varying sizes of occupants — a total of four tests in all.

Along with the traditional movable, deformable barrier that crashes into test vehicles from the side, the new standard could also call for a "pole test," in which a utility-type pole smashes into its side on an angle.

Also, the Insurance Institute for Highway Safety is pushing for protection against a "high hood" crash, in which a larger vehicle, such as an SUV, strikes a smaller one from the side.

Supplier engineers say that all the new tests and requirements combine to pose major challenges. "The high hood is about 20 percent to 30 percent faster than a typical side impact," said Madana Gopal, a staff development engineer for Delphi Automotive Systems (Troy, Mich.). "That means your sensing system has to be that much faster."

Engineers say the computing problem goes beyond a growing amount of data for processors to sort through. Both the data and the decision-making process itself, they say, are growing more complex.

"As the algorithms become more sophisticated in order to pick up on all the new crash information, there's going to be a need to process the information faster," said Charlie Steffens, director of safety systems technology for TRW Automotive (Livonia, Mich.).

Eventually, engineers believe that side-airbag systems could migrate from conventional microcontroller-type control toward DSPs as a means of dealing with the blizzard of data being sent to them. "If system makers have not already deployed higher-performance processors, then the new demands will drive them to it," said Martha Sullivan, vice president of sensor products for Sensors and Controls at Texas Instruments Inc. (Dallas).

Ultimately, the complexity of the new side airbags is also expected to motivate a push toward faster data buses. The controller-area network (CAN) bus, commonly used in many vehicle applications, is believed to be insufficient for the future needs of side-airbag systems.

"CAN and some other existing buses are either too slow or don't have enough redundancy," said Zawadzki of Analog Devices. "Also, they don't have other aspects of robust systems, such as error checking, serialization and programmability."

Less than $4
Electronics suppliers are greeting the advent of side airbags by stepping up production of accelerometers and pressure sensors. Analog Devices, for example, has developed a "satellite" accelerometer that incorporates an ASIC for signal conditioning. Using the ASIC, a "conditioned" signal can be pumped directly into an analog-to-digital converter and then sent to the main module, without the need to add external signal-conditioning circuits. The company said last week it can integrate all the components in a package that sells for less than $4.

Competitors such as Texas Instruments plan a different approach. The company said last week that it is producing pressure sensors that could be packaged in door cavities, where they would measure an air pressure change inside the door during a side impact. Pressure sensors offer the advantage of a faster reply than accelerometers, which is why several airbag systems manufacturers, such as TRW and Delphi, are talking about using the two device types in combination.

Supplier windfall
The proposed NHTSA regulation could lead to a windfall of sorts for some electronics suppliers, which typically charge between $4 and $7 apiece for microelectromechanical-systems (MEMS) devices. Suppliers estimated that the worldwide market for airbag sensors would have hit 150 million units per year by 2009 without the new proposed standard. With it, that figure could climb to more than 200 million, just for airbags.

In addition to the two sensors already located in the "crush zone" in the front of most vehicles, automakers will probably add laterally mounted accelerometers in the airbag electronics module at the firewall, as well as pressure sensors in the doors and accelerometers on the support beams around the vehicle's windows, known as the A-pillars and B-pillars.

To be sure, automakers aren't required to meet the NHTSA standard with side airbags, even if the proposal is adopted. To date, though, no other notable technique for safeguarding against side impacts has emerged.

"A new standard is likely to drive us in a direction where deployable systems may be the only way to get it done," said Steffens of TRW. Those "deployable" systems could be costly, however.

Automotive engineers last week estimated that a typical side-airbag system would cost a minimum of $150 on sedans and a maximum of more than $300 on jumbo SUVs, such as the Chevrolet Suburban. Many OEMs plan to use an inflatable "curtain" bag that covers both the front- and rear-seat occupants. Some might also use seat-mounted and door-mounted bags to protect the occupant's lower thorax, as well as the head. "In theory, you could have some vehicles with as many as six airbags," Steffens said.

U.S. automakers said last week they will push for broader adoption of side-airbag systems, with or without a nudge from NHTSA. General Motors said 50 percent of its vehicles will meet the new criteria by Sept. 1, 2007 and 100 percent will meet it by Sept. 1, 2009. The Alliance of Automobile Manufacturers, which includes BMW, DaimlerChrysler, Ford, GM, Mazda, Mitsubishi, Porsche, Toyota and Volkswagen, has also endorsed the idea. Industry watchers said that if Japanese carmakers are forced to put the sensors in all their cars sold in the United States, they will put them in most Japanese vehicles, as well, for economies of scale.

"We do see some issues that need attention and clarification in terms of the engineering," said Jim Khoury, manager of advanced safety development for General Motors (Warren, Mich.). "But, in principle, we're behind the idea of improving side-impact protection."