PORTLAND, Ore.—Inertial measurement units (IMUs) integrate a three-axis accelerometer and a three-axis gyroscope, which Bosch Sensortec now claims to have put into the smallest package yet available for consumer-grade applications such as mobile phones, tablets and digital cameras.
Frank Melzer, Bosch Sensortec CEO, announced the integration into a single inexpensive 3.0-by-4.5 millimeter package at the MEMS Business Forum Thursday (May 24) in Santa Clara, Calif.
Every smartphone today has a three-axis accelerometer to track motion—for automatically switching its screen from portrait to landscape—but for advanced gaming, gesture recognition and indoor navigational tasks, a three-axis gyroscope is needed, too. Accelerometers only track linear motion, but gyroscopes track rotation-in-place motion, thus providing a higher precision when tracking fine user movements. Packing both accelerometers and gyroscopes into a 3.0-by-4.5 millimeter package could enable any smartphone can upgrade to a full six-degree-of-freedom inertial measurement unit (IMU).
"Bosch Sensortec is now offering the smallest IMU available today," said Leopold Beer, director of global marketing at Bosch Sensortec. "We are the only MEMS manufacturer who makes accelerometers, gyroscopes, magnetometers and barometers in-house."
Bosch has both 6-inch and 8-inch MEMS fabs in Reutlingen, Germany, capable of building 1,500 wafers per day at 0.5 micron and 800 wafers a day at 0.18 micron, respectively. They are also the only manufacturer making two six-degree-of-freedom (6-DoF) parts with their own chips—an accelerometer/magentometer combo for e-compasses and navigation, and now an accelerometer/gyroscope combo for gaming and gesture recognition. With the addition of one of their barometer chips—for determining altitude—Bosch Sensortec now also has a complete 10-DoF intertial navigation unit (INU) as a two-chip solution.
Bosch Sensortec wire-bonds together into 3-D stacks the MEMS die and the ASIC holding its electronics all in a single package.
Source: Bosch Sensortec
Bosch's gyroscopes offer several operating modes to save power, enabling to power down by half and awaken in just 10 milliseconds or go into sleep mode and awaken in just 30 milliseconds, triggered by any user motion detected by the accelerometer. Both the accelerometer and the gyroscope can also be interrupt driven, plus include on-chip first-in-first-out (FIFO) memories for logging data values between polling periods. Accelerometers since plus or minus 2-to-16 Gs and gyroscopes run at form plus or minus 125-to-2000 degrees per second. Resolutions range from 12-bit for accelerometer to 16-bit for gyroscopes.
Bosch's sensor fusion library also contains routines for all the common uses of accelerometers and gyroscopes such as background calibration to keep all sensors in tune, group delay compensation for real-time motion tracking, tremor cancellation for gaming and pointing, distortion detection and suppression for magnetic immunity and stability enhancement for indoor navigation. And an application programmer interface permits turnkey operating system integration with Android.
Bosch is not the first to integrate a gyroscope and an accelerometer onto the same chip. Combo chips are already available from Invensense:
However, Bosch's manufacturing muscle as the world volume leader in MEMS worldwide may attract mainstream smartphones since it takes the place of separate chips for accelerometer and gyroscope. STMicro, which supplies the iPhone today, has a combo chip with three-axis accelerometer and two-axis gyroscope, that it sells to Movea for its pointing TV remote controls:
However, today Apple smartphones and tablets still use separate accelerometer and gyroscope chips, both from STMicroelectronics.
I forgot to mention that Invensense also already has the holy-grail of inertial navigation--a complete nine-axis inertial navigation unit (INU) that includes an AKM magnetometer along with its own six-axis combo chip with accelerometer+ gyro (IMU):
Also Bosch has a eCompass, a six-axis accelerometer plus magnetometer of its own design:
And its only a matter of time until Bosch, and STMicroelectronics for that matter, release complete nine-axis INUs too.
Exactly Les. Inertial navigation would be significantly easier. I can see lots of products being helped out especially small micro drones and radio control craft of all sorts. Could be used to track items or people beyond the reach of GPS (for good or bad).
Yes, dead reckoning in navigators like Garmin when GPS is blocked will be one application, and Bosch supplies the sensor fusion software to make that happen. However, the higher-volume usage, Bosch hopes, will be in replacing with this single chip the separate chips for accelerometer and gyroscope in smartphones and tablets like the iPhone and iPad.
I agree to everything above. In the long run combo sensors will prevail. As product manager at Bosch Sensortec I strongly believe that Bosch Sensortec's strong MEMS integration competence paired with holding the key MEMS technologies and the sensor data fusion know-how in-house is an inherent advantage. The picture above shows the eCompass BMC050, a 6-axis device consisting of a state-of-the-art 3-axis accelerometer and a high performance 3-axis geomagnetic sensor. It is another example for Bosch defining the standard for the smallest footprint.
One thing I forgot to spot-light but only mentioned in the story above, is that gyroscopes ordinarily burn battery power, because they use a resonator that has to be running full speed before the sensor works. However, Bosch has set-up its combo accelerometer/gyroscope chip so that the gyro, even though it is internal, can still be turned off by the accelerometer when the device is idle for a while.
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