Sensor fusion powers smartphones and tablets

Motion sensing capabilities in products like the iPhone and iPad now are set to move to the next level with the advent of sensor ‘fusion’, a more sophisticated approach that will spur a fundamental shift in the way tablets and smartphones are designed and used, according to IHS iSuppli.

“Microelectromechanical system (MEMS) sensors—mainly gyroscopes, accelerometers and compasses—are becoming ubiquitous in smartphones and tablets,” said Jérémie Bouchaud, director and principal analyst for MEMS and sensors at IHS.

“While these sensors already provide user interface, gaming and navigation features that are essential to the appeal of today’s mobile electronics devices, taken individually they have limitations in areas including accuracy and responsiveness. To attain the next level of functionality, handsets and tablets must provide to developers a ‘fused signal’ that combines the outputs of these three types of motion sensors to greatly enhance the motion-based interface.”

Sensor fusion potentially could enhance interfaces of any tablet or smartphone that uses a combination of a 3-axis accelerometer, 3-axis compass and 3-axis gyroscope to provide ‘9-axis sensor fusion’, IHS predicts. IHS estimates there is a total available market for motion sensors that need 9-axis fusion amounting USD 850 million in 2012, and rising to USD 1.3 billion in 2015.

Better sensors for better products
Gyroscopes, accelerometers and compasses each provide a different form of motion sensing. However, each sensor type has its own limitations. For example, the gyroscope suffers a strong drift over time, the compass is sensitive to electromagnetic interference and the accelerometer works better for slow movement than for fast motions.

When the signals of the three sensors are fused together, each sensor function can compensate for the others’ inherent limitations. This will yield a truly enhanced motion sensing experience that is much faster, smoother and more accurate than is possible with each sensor used individually.

However, the true benefit of combining the three devices will only be evident when a 9-axis sensor fusion is included in the applications programming interface (API) for apps developers.

“With the integration of 9-axis sensor support in the API, apps developers will be able to produce software with compelling smartphone and tablet functionality, such as immersive games and very responsive and accurate augmented reality applications for outdoor use,” Bouchaud said. “The use of 9-axis sensor fusion will also enable full indoor navigation,”

Such a development will represent a major improvement for both the Apple iOS and Android operating systems, which at present don’t support full 9-axis integration from either a hardware or software perspective.

On iOS, the output signal of the gyroscope is combined with that of the accelerometer to provide 6-axis fusion. While this enhances the motion-based use of an iPhone compared to the iPhone 3GS for augmented reality applications, the function falls short of the full 9-axis fusion.

On Android handsets and tablets that already have a gyroscope, only the raw data of the gyroscope is made available, with no combination with the accelerometer signal. Because of this, there is not a single noteworthy application on the Android Store that uses the gyroscope function.

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