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Car MEMS may face safety hurdles

Posted: 27 Mar 2012 ?? ?Print Version ?Bookmark and Share

Keywords:MEMS sensor? automobile industry? safety standard?

In spite of the range of benefits MEMS sensors can offer the automobile industry, a recently published standard, ISO26262, could negatively impact the momentum. This was the overlying tone of the recent MEMS panel. The sensors could aid in applications such as self-parking and autonomous vehicles, but unless MEMs makers implement more complex design procedures for the devices, the safety standard could exclude them from selling in to the automotive supply chain, said a panelist from Continental Teves AG.

ISO26262 applies more generally to silicon and software although the role of MEMS sensors in a number of safety-critical systems makes the standard particularly relevant to MEMS components.

The general automotive MEMS scene was set by panelist Richard Dixon, MEMS analyst with IHS Inc. He said the automotive market had recovered well from the stall of 2008-2009. He added that the market for automotive MEMS sensors had grown 28 percent in 2010 and, more surprisingly, by 15 percent last year to a value of $2.2 billion. For the period 2010-2015 the industry is entering a faster growth phase with a CAGR of 10 percent to take the market to $3 billion in 2015, he continued.

Dixon named the usual MEMS sensor suspects, pressure sensors in the powertrain and tire pressure monitoring system, accelerometers in the airbag safety system and gyroscopes in electronic stability control (ESC) systems. He said that IHS has spotted 36 design slots for MEMS in the automobile but that growth would come as more regions adopted mandates that demanded these slots be filled. This year, Japan is adopting an ESC mandate that will drive some growth while China is expected to require TPMS in the next three years.

Meanwhile automobile purchasing worldwide is set to increase from 70 million cars in 2012 to 100 million cars in 2015. In terms of growth beyond that, it is likely to be sensors to monitor and help automotive companies cut down on emissions, Dixon noted.

Hannu Laatikainen, EVP responsible for transportation business at VTI Technologies Oy, argued that MEMS should provide an automobile with a sensory system like humans. "We have eyes and ears. We should have cameras and microphones, we should measure friction [traction of the tires], we should taste the fuel. We should even have a nose for the car." In response, Dixon pointed out that it is now a legal requirement in France to carry a breathalyzer in the car.

Extra demands on MEMS makers
It was left to Marc Osajda, global automotive strategy manager at Freescale Semiconductor Inc., to bring the panelists and the audience down to earth. He made the point that although the market might increase the pressure would come from automobile makers to do all the difficult things: to reduce size, reduce power consumption and reduce cost. The latter was particularly true as much of the expansion of the market would be coming in emerging markets and costs would have to be reduced significantly to hit car price targets.

Bernhard Schmid, manager of sensor systems at Continental, didn't disagree on this point. But his wish list included car-to-car and car-to-infrastructure communications, for enhanced traffic safety, as well as more robust, less sensitive, lower cost MEMS sensors.

There followed a dialog between Freescale's Osajda and Continental's Schmid that explored the likely impact of ISO26262. The standard, published in November 2011, provides requirements, processes and methods to mitigate the effects of systematic and random faults. The standard requires proof of risk assessment and documentation of the steps taken to avoid systematic and random errors in functional systems in product development. This might include the inclusion of such things as redundant systems.

Osajda's initial position was that the standard, with its classifications of A, B, C and D levels of automotive safety integrity levels, takes a system-level view of safety in road vehicles. "It is a system architecture thing."

Schmid's interpretation was different. "Sales into automotive requires that MEMS makers change the way they develop and manufacture." One of the main requirements is the documentation assembled during the MEMS design process to prove that safety has been considered and the measures that have been taken and that can be passed downstream to the tier-1 and on to the automobile maker.

Some car makers have reportedly been asking for ISO26262 compliance since early 2011 although most silicon and software, developed before the publishing of the standard, is inherently non-compliant. Schmid said that MEMS makers must respond if they want to sell to tier-1s.

Other concerns raised from the floor included that visual sensors would replace inertial MEMS as image sensors together with software can be better at analyzing dangerous situations ahead of impacts and helping with avoidance. Schmid tried to relieve some concern by making it clear there is room for a wealth of sensors in Continental. "Think of your human senses. Your eyes didn't cannibalize your ears."

- Peter Clarke
??EE Times

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