Friday, May 25, 2012

You make MEMS. Should you make sensor fusion software?

May 25, 2012 -- Sensor fusion is a software solution to improve the operation of multiple micro electro mechanical system (MEMS) sensors in concert. Through sensor fusion, gyroscopes, accelerometers, pressure sensors, magnetometers, and other devices can be operated together to compensate for inherent sensor weaknesses and enable new precision and new applications. “Combination sensors are a marginal player now but expected to penetrate 40% of the $2.7 billion consumer inertial market and 12%+ of the $1.1 billion automotive inertial market by 2016,” according to Yole D√©veloppement.

With 5-10 MEMS devices integrated into every smartphone, tablet, and other electronics, sensor fusion can be a differentiating factor in product capabilities and performance. No surprise then that so many companies -- software suppliers and MEMS makers -- are increasing their efforts in sensor fusion development.

I recently spoke with Leopold Beer, marketing leader at Bosch Sensortec, the consumer MEMS division of Bosch, about a new inertial measurement unit that was developed concurrently with gen-2 of Bosch’s sensor fusion software, FusionLib. “The hardware and software are not 2 separate new products,” said Beer, “they work together. The physics of sensing are the same as they were 10 years ago,” he added, “we can provide better products because of miniaturization and sensor fusion.”

MEMS manufacturers are the best companies to do sensor fusion development, not software suppliers, because they understand the performance and physics of each MEMS device intimately, Beer said. MEMS are a highly varied group of semiconductors, with little standardization from one to the next. And every MEMS sensor performs differently. “When designing a system using multiple MEMS sensors, it is important to understand the advantages and disadvantages of accelerometers, gyroscopes, magnetometers, and pressure sensors,” said Jay Esfanyari et al, STMicroelectronics, in our July 2011 cover article, “Solutions for MEMS sensor fusion.” STMicroelectronics is a major manufacturer of MEMS components. Beer envisions handsets and other electronics that use device-specific sensor fusion to optimize and calibrate MEMS performance, and some level of hardware-agnostic sensor fusion that connects all the sensors in a device, if they are not all from the same manufacturer. Detailed knowledge of sensor fusion techniques is also important to the system as a whole, because some algorithms lead to higher power consumption than others, and some MEMS devices draw more power than others. A sensor fusion strategy should be selected for, in addition to improving performance, its impact on system-level power consumption, noted Esfandyari et al.

Another group of companies provides sensor fusion software -- hardware-agnostic software developers. Hillcrest Labs and Sensor Platforms both released sensor fusion programs recently. Motion control software can “limit sensor choice, integration flexibility, and performance” in the system design, said Chad Lucien, senior vice president of sales and marketing for Hillcrest Labs. The major benefit of software-company sensor fusion is that MEMS can come from any manufacturer in the marketplace. For high-volume applications that require secondary sourcing of components, a hardware-agnostic sensor fusion platform eliminates supply bottlenecks.

The MEMS supply chain will change, according to Yole, as companies "figure out how best to compete and cooperate for the much bigger business of integrating the silicon sensors into useful functions...Players in the MEMS industry can compensate for price declines by selling high-value solutions that include more software content. Higher-value software calculations might require an MCU, not the usual ASIC. Makers of microcontrollers, software, and subsystems will start to take over more of the sensor management.”

As MEMS become more pervasive in everyday life, industrial and military instruments, vehicles, and other applications, sensor fusion will be an increasingly important consideration, and a potential differentiator for MEMS manufacturers.

--Meredith Courtemanche, digital media editor,

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