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Consumers prefer MEMS-enabled mobile devices

Posted: 01 Aug 2011 ?? ?Print Version ?Bookmark and Share

Keywords:MEMS? inertial sensors? user interface? magnetometers? accelerometers?

The iPhone and Wii devices changed the whole realm of user interface with MEMS accelerators that enabled natural motion as an input mechanism. However, it took a while for designers to make the best out of these capabilities.

Now, inertial sensors are starting to move into a wider range of motion control and precision location applications, together with lower costs, and by the generally maturing of the knowledge base and infrastructure that are making the sensor data easier to use.

Yole Dveloppement projects these developments will drive accelerometers and magnetometers to be designed in to close to 50 percent of all mobile phones within five years, and gyroscopes to be included in some 20 percent, mostly at the higher-end smart phone part of the market. Gyroscopes are already in almost all tablets, mostly because Apple still so dominates that market with better than 90 percent share. We expect usage of inertial sensors in consumer electronics will increase by about 24 percent on average annually for the next five years, to reach some 5 billion individual sensor units by 2015.

Adoption driven by lower prices, better software
Major applications for inertial sensors outside of games so far have actually been somewhat limited. Accelerometers have become a must-have in mobile phones for switching between portrait and landscape mode, and seen scattered use in pedometer functions. Magnetometers hit mass adoption in phones last year, to supply correct heading for navigation. Multiaxis MEMS gyroscopes have just reached consumer price points and volumes and are showing up in first phones and essentially all tablets, although initially largely for games.

But lower prices are helping drive wider adoption. Yole sees costs of discrete inertial devices continuing their steep decline, with the ASP of a three-axis accelerometer, for example, dropping from $0.70 in 2010 to around $0.30 by 2015or less than $0.10 per axis. Part of these cost savings will be driven by sharing the cost of one controller ASIC between two sensor devices, by packaging the accelerometer and the magnetometer, or the accelerometer and gyroscope together as one combination sensor with one ASIC. This can also improve the sensor data, directly building in the corrections of each sensor for the deviations of the other.

Also driving adoption is the fact that it's getting much easier to turn the sensor output into useful applications. The leading MEMS device makers like STMicroelectronics and InvenSense are supplying more software and libraries to make it easier for the phone and tablet makers to add basic motion functions to their systems. Dedicated motion sensor software suppliers like Movea and Hillcrest Labs are supplying device-agnostic software to allow wider applications, particularly for air mice and TV remotes to do control by gestures. And the latest version of Android operating system software supports some motion processing APIs, with more sophisticated versions expected to come.

Bellwether applications worth noting
LG's Optimus Black Android phone uses a gyroscope to enable its convenient one-hand interface, where the user can move from screen to screen by tilting the phone. (A thumb button on the side of the phone activates the gyro for use.) This phone is also the first to use a gyro from MEMS startup InvenSense, a big design win for a small fabless company that attests to the maturity and volume reliability of the MEMS foundry supply chain, as well as to the software support for turning sensor data into functions from both InvenSense and Android. Gyros will likely also soon find use for image stabilization to improve the quality of cell phone photos.

Gyroscopes are also appearing in TV remote controls that aim to ease the use of Internet TV. LG is now shipping a TV with a point-and-click remote control using motion control software from Hillcrest Labs that does the sensor fusion, calibration and signal processing to remove imperfections in the data and compensate for temperature variations for a more precise data stream, then wraps it with a mouse pointer function, for precise point and click to easily navigate the many TV options. The large remote control OEMs SMK and Universal Electronics are also customers. Hillcrest has also helped to evangelize the idea of motion control and move the infrastructure along with its own ring-shaped point-and-click remote control and a computer web browser designed specifically for computers linked to the TV. LG's involvement has also spurred development of graphic interfaces for point-and-click TV navigation from a number of major television content suppliers. Internet service providers and set top box makers are getting into the act as well. France's Free ISP has introduced a set top box designed by Philippe Starck with a motion sensing remote with Movea software to control its extensive menu of live and streaming TV, internet, gaming and phone services.

But the major driver for inertial sensors in mobile consumer devices going forward is likely to be the demand for more accurate location and navigation applications. GPS chipset makers report their customers are asking for more reliable pedestrian navigation capability that combines outdoor and indoor maps for location-aware searches, so users can find what they want, where they want it. This useful level of accurate navigation depends on having not only an accelerometer and a magnetometer, but also a gyroscope and a pressure sensor, to accurately track steps and changes in direction and level to be able to locate the user by dead reckoning when radio or satellite signals aren't available. Here too the infrastructure is developing, with indoor maps of major U.S. destination locations like malls and airports now available from suppliers like Point Inside, indoor location signals installed by some interested store or mall management, and advertisers testing various hyper-localized information or offers. First localized search applications like Gas Buddy, OpenTable and Groupon's "I'm Hungry", which don't need particularly high accuracy of location, are finding traction with consumers in the US. More detailed search within stores or augmented reality that can show information about particular places will however require the full set of accurate, low drift sensors to improve precision from tens of meters down to within meters.

- Laurent Robin
??EE Times

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