Author Archives: MEMS Industry Group

MEMS Industry Group® (MIG) is the trade association advancing MEMS across global markets.

Improved electronic compass software released: Xtrinsic eCompass software

Originally posted by Michael E Stanley of Freescale Semiconductor in The Embedded Beat on April 29, 2013

A few weeks ago, my coworkers and I had the pleasure of participating in an awards ceremony in which Electronic Products Magazine presented Freescale with a Product of the Year award for our Xtrinsic eCompass software. This software processes the outputs of two sensors (an accelerometer and a magnetometer) to implement a tilt-compensated electronic compass. The software is available in source code format supported by an easy-to-use click through license.

We were at revision 2.0 of that library when Electronic Products announced the award. Since then, revision 3.0 has been uploaded to our web site. To download, click on the ECOMPASS_SW link on the Xtrinsic eCompass software page, read and approve the license agreement that pops up (you can freely use this software in products which include Freescale magnetometers and accelerometers), and save the offered .zip file onto your hard drive.

 

When you expand the zip file, you will have a folder called “eCompass”, with sub-folders: “Documents” and “Software”.  This is a major new release. I’m going to claim it to be the best-documented e-compass solution anywhere, thanks to the Herculean efforts of my good friend Mark Pedley, who also supplied much of the content for this post. Here’s what you’re going to find in the “Documents” folder:

  1. Software for Tilt-Compensated eCompass with Magnetic Calibration (v3 Release) User Guide
  2. AN4676 – Euler Angle, Rotation Matrix and Quaternion Representations of Orientation in Aerospace, Android® and Windows 8® Coordinates
  3. AN4684 – Magnetic Calibration of Hard and Soft Iron Interference
  4. AN4685 – Tilt-Compensated eCompass in Aerospace, Android and Windows 8 Coordinate Systems
  5. AN4696 – Accelerometer and Magnetometer Sensor Simulatoin for Tilt-Compensated eCompass
  6. AN4697 – Low Pass Filtering of Orientation Estimates
  7. AN4698 – CPU, Flash and RAM Benchmarks : Xtrinsic eCompass and Magnetic Calibration Algorithms
  8. AN4699 – Data Structures for Matrix and Vector Algebra
  9. AN4700 – Control Loop, Data Structures and Compile Time Constants
  10. AN4706 – Accelerometer and Magnetometer Selection and Configuration

 

The software itself has been expanded and improved.

Flow chart.jpg

The “Software” directory contains half a dozen C source and header files that contain everything you need to implement your own e-compass. It also includes a pre-compiled command line tool that lets you simulate performance of the e-compass. The ANSI C source code is processor agnostic allowing Freescale customers to retain their existing MCU architecture. The software is highly optimized to minimize use of program memory, RAM and floating point calculations. Software features include:

 

  • The code compiles into 10KB of ARM Thumb2 object code and uses less than 4KB of RAM.
  • A dedicated floating point unit (FPU) is not required and the software can run on typical 32 bit integer processors with software floating point emulation.
  • Orientation is provided in Euler angle (roll, pitch, yaw and compass heading), rotation matrix and quaternion formats.
  • Supports Aerospace, Android and Windows 8 coordinate systems
  • Tilt-compensated
  • Programmable low pass filter
  • Quality of fit metric indicates expected compass heading error
  • Resilient to magnetic jamming corrupting calibration
  • Three levels of hard and soft iron magnetic calibration are provided at increasing levels of performance and computational complexity.
    1. The simplest 4 element calibration solver computes the hard iron correction vector and geomagnetic field strength and removes the largest component of the magnetic interference caused by ferromagnetic components on the circuit board. It consumes 3300 floating point operations per call.
    2. The seven element calibration solver corrects for differing magnetic permeability along the three Cartesian axes and is suitable for the more complex calibration environments found in the dense circuit board layouts of smartphones and tablets. It consumes 20,000 floating point operations per call.
    3. The 10 element calibration solver computes a best-fit solution to the 10 dimensional magnetic optimization problem including off-diagonal elements of the soft iron matrix. It consumes 62,000 floating point operations per call.

The web-release includes source for options 1 and 2 above. Option 3, the highest performing 10 element calibration solver, is not available in source form, but is available under license in object code format for ARM Thumb2 processors.

 

If you have used previous generations of our e-compass software, you will see major improvements in the feature set above. I like the fact that it now supports any of three different orientation representations right out of the box. The math behind an electronic compass isn’t easy, but Mark has done an excellent job of breaking it down into manageable chunks that are easily digested. So please, download the new release, give it a go and let us have your feedback.

 

References are available on the original blog post. 

Who’s Driving the MEMS Evolution Revolution? (Part 1 of 3)

I am pleased to bring you part one of a three part series on the MEMS Evolution Revolution, written by my colleague, and long-time MEMS industry insider, Howard Wisniowski. Howard takes us with him to “visit” three exciting MEMS startups that are breaking new ground in the mobile/consumer market. In part one, we learn about bulk acoustic wave (BAW) solid state MEMS gyroscopes and meet MIG member company Qualtré. In parts two and three we journey to find out what companies are driving the MEMS evolution revolution with their exciting nascent disruptive technologies. I hope you are as excited as I am to read this series and I welcome you share your stories of other MEMS startups that are breaking out in their own markets, whether it be in agriculture or acoustics; healthcare or helicopters. MEMS truly is everywhere and it’s likely the innovative smaller companies who will spread it further, faster and for longer. Viva la Revolution!

 

Who’s Driving the MEMS Evolution Revolution Now?

Part 1

Howard Wisniowski, Freelance Editor

Like the transistor and the microprocessor, MEMS are often described as a disruptive technology, as in change-the-world, turn-it-upside-down, rewrite-the-rules-of-the-game. You can forget about this kind of incremental change, however, fitting easily into corporate business plans. Few, if any, roadmap processes are available to accommodate new innovative disruptive technologies that either have the potential to radically change the way products are currently being produced or are the foundation for products that might create entirely new industries, nascent disruptive technologies. Within many established corporate environments, roadmaps all too often focus on sustaining existing technologies with a mature sales base and use variations of tried and true processes that exist in their fabs. Start-ups don’t have these types of investments enabling them to build on the shoulders of their predecessors and develop products that take a fresh look at what benefits product design engineers are seeking for new and existing end applications.

Today on the “revolution” side, the demand for MEMS technology is still booming thanks to not only to the continued growth of high volume automotive and consumer applications where MEMS sensors have become mainstream, but also to the continued development of emerging applications in robotics, energy harvesting, and healthcare. On the “evolution” side, however, there are even more exciting and disruptive things going on with MEMS technology that is poised to drive the next wave of MEMS enabled products and applications. There are hundreds of companies, universities, and thousands of researchers around the globe working on MEMS projects. Many have the underlying technology that is well beyond the laboratory, ready for deployment, and are now seeking funding.

Highlighting this very active sector, Yole Development reports on the continuing growth of emerging MEMS products and applications. Alongside many of the old timers, their reports cite as many as 50 startups designing emerging MEMS devices that have the possibility to ramp up to large volumes quickly with growing access to contract foundries.

Within this large field, several new “disruptive” MEMS devices will be highlighted in this three part series beginning with bulk acoustic wave (BAW) MEMS technology. This new and disruptive MEMS technology is now being applied to innovative MEMS gyroscopes.

 

Bulk acoustic wave (BAW) solid state MEMS gyroscopes

According to analysts at IHS iSuppli, the MEMS gyroscope market displaced accelerometers as the revenue champion in consumer and mobile MEMS applications when revenue grew 66 percent from $394 million in 2010 to $655 million in 2011. While engineers now design systems that include MEMS gyros as essential components, particularly designers of mobile devices, suppliers are scrambling to meet their needs for low power, small size and low cost.

Qualtré, Inc. (Marlborough, MA) is one MEMS start-up and MIG member that is addressing these issues with an innovative MEMS technology referred to as bulk acoustic wave (BAW) technology. BAW technology is now being used to pioneer a new class of solid state stationary gyroscopes that not only meet power, size and cost requirements, but also add high performance to the mix. Unlike older MEMS gyro technologies that use moving masses vibrating at low frequency range of 5 to 50 kHz (I don’t want to get too technical here), BAW MEMS gyros operate in the megahertz frequency range (1‐10MHz), several orders of magnitude higher. This is enabled by the very stiff nature of the BAW technology. This stiffness not only results in MEMS gyros that are insensitive to vibration in the environment but also prevents stiction both in manufacturing and during operation in the field, thus removing a major yield and reliability problem found with the vast majority of other MEMS devices. These features results in improved performance in real world applications where vibrations are present and degrade the operation of current gyros.

By combining these performance advantages of the BAW sensor design and the scalability of Qualtré’s proprietary HARPSS™ process (High Aspect-­Ratio Combined Poly and Single-­Crystal Silicon), BAW MEMS gyros have also demonstrated very stable signals (aka low drift) which is important for pedestrian navigation, improved noise density for better resolution and more accurate measurements, and a wider dynamic range that expands detectable signals. This kind of innovation is what will drive the next wave of end-product product designs for new and existing applications.

Karen’s blog from MEMS Executive Congress: Part 2

I last left you hanging, waiting to hear more about the heated conversations between the panelists and the audience – and I have to tell you, it really started heating up in the audience during the energy panel. Ooo baby it was jumping.

MEMS Executive Congress Europe 2013MEMS in energy can mean a lot of things – and our panelists diverse perspectives discussed a great deal, but the majority of the audience wanted to focus on the topic of MEMS in energy harvesting. Though not necessarily experts in this field, thankfully our panelists were up to the challenge. Our moderator was Bert Gyselinckx, General Manager, Holst Centre, imec; Wim C. Sinke, Program Development Manager, Solar Energy, Energy Research Centre of the Netherlands; Eric Yeatman, Professor of Microengineering, Deputy Head of Department, Imperial College London; and Harry Zervos, Senior Technology Analyst, IDTechEx. I actually should probably add Rob Andosca of MicroGen Systems as a fifth panelist as he was eager to ask and answer any question from the audience with his BOLT energy harvester in hand.

I loved the diversity of perspective on this panel –Wim for example does not have an entirely MEMS-centric background. His expertise is in solar and photovoltaic energy and he spoke of how multiple technologies will work together to make reliable and sustainable energy system, as well as the importance of portfolio management – combining different energies in an active way to make it work. We in MEMS could learn a lot from guys like Wim (I hope everyone picked up his business card; I know I did).

The panel also spoke about wireless sensor networks and Harry gave a great overview of the three technologies that are converging: 1. Microgenerators and energy storage (vibration, solar, heat, tree resin, etc.); 2. Ultra low-power electronics (currently being developed) – helping power sensors; and 3. Transmission protocols that don’t need a lot of power to send data. Eric followed up with the poignant view that until things become truly wireless, you can’t really have wireless sensor networks. And once they are wireless how will they be powered – by energy harvesting or battery? This opened the floodgates and I, with microphone in hand had to jog all over the audience to capture the comments and follow-up questions from the audience.

Let me be diplomatic and say that there is no clear consensus out there on MEMS energy harvesting. And out came the very clever quotes including some of my favorites including this one from Wim: “Don’t look at MEMS as the energy harvesters, MEMS are the enablers to help realize energy savings.” And this one from someone (maybe you’ll remember and leave a comment here)  “I’m happy to hear everyone in MEMS talking about energy, but I can assure you that not everyone in energy is talking about MEMS…yet.” And Bert’s: “MEMS will probably not be main source of energy replacing nuclear power plants soon; but MEMS will enable increased intelligence in energy applications.” As great as these sound bytes were, the show stealer came when Rob Andosca stood up and talked about how cows are being used for energy harvesting and gave us the best quote: “You power the Moo-mometer with MEMS because cows get dirty.” Tech-Eye reporter Tamlin Magee loved that one too and plans to write a story on – perhaps cow-power is the next big thing!

MEMS Executive Congress Europe 2013The last panel of the day before the closing keynote was MEMS in medical with a focus on aging moderated by Frank Bartels, Founder (Bartels Mikrotechnik), President (IVAM). Panelists were:  Heribert Baldus, Principal Scientist – Personal Health Solutions, Philips Research; Jérémie Bouchaud, Senior Principal Analyst, MEMS and Sensors, IHS iSuppli; Kimmo Saarela, CEO, TreLab Oy; and Axel Sigmund, National Contact Point MTI/DW and Ambient Assisted Living Joint Programme, VDI/VDE Innovation + Technik GmbH. This was another diverse panel with varying views on how to address the medical and healthcare issues of the world’s aging population.

 When asked how MEMS is enabling a better quality of life with regard to prevention, monitoring, management, replacement and rehab I think Kimmo summed it up best when he said that with MEMS we can put so many things into a small form factor, which entices people to use our products. MEMS sensors allow us to collect raw data from so many sources. Data analysis is the key benefit and is their “value add” to the customer. But the key thing here is that power consumption and size really matter. Heribert added that MEMS is enabling an aging population to detect issues in their daily lives and manage their lives. I like to say it gives them their dignity back – and that is no trivial thing.

Jérémie spoke of some of the mass markets already present for MEMS in aging including sleep apnea disorders and oxygen therapy. There are also mass markets for MEMS medical applications that are in the hospital (not yet in the home) including disposable blood pressure monitors as well as dialysis and drug infusion applications. This kicked off a discussion about an aging population living at home which is becoming more of a critical issue in Europe, and a main focus of what Axel is addressing at VDI/VDE Innovation + Technik.

At the close, the panelists were asked what they saw as the future of medical – Heribert said he’d like to see more sensor integration, more intelligence and far less power. Jérémie said he sees a future for gas sensors analyzing the breath (and will not require FDA approval). Axel sees non-invasive diabetes monitoring as having the biggest impact; while Kimmo echoed Heribert and sees a future of more integrated solutions where biometric sensors will give more data and aid early detection and intervention. Frank agreed with Jérémie that gas sensors will be next once the pump issue is solved and that the time for microfluidics is near.

This final panel set things up perfectly for our closing keynote, Renzo dal Molin, Advanced Research Director, Cardiac Rhythm Management business unit, SORIN GROUP. Renzo gave the presentation “Vision for Implanted Medical Devices Healthcare Solutions and Technical Challenges,” which outlined the opportunity for implantable medical devices. He described in detail how

MEMS Executive Congress Europe 2013

the next generation of medical devices will come from miniaturization of devices, reduction of power consumption, and wireless capability and yes, even spoke of energy harvesting (you can guess whose ears perked at that statement). Renzo then highlighted how the BioMEMS market is expected to grow from $1.9 B in 2012 to $6.6 B in 2018 thanks to the inclusion of accelerometers in pacemakers and homecare monitors; MEMS sensors for glucose meter connected to smartphones; MEMS microphones for hearing aids as well as MEMS insulin pumps.

The audience was excited to discuss where Renzo saw the future of BioMEMS going, and where he felt the industry should focus moving forward. Renzo agreed that in the near future (once regulatory hurdles were overcome) patients will be able to monitor their implantable devices on their mobile devices. And he felt the next big thing will be biomarkers, as well as MEMS-enabled devices that could give an ECG will be revolutionary to the medical field.

MEMS Executive Congress Europe 2013And with that it was time to break and enjoy a fantastic evening at the Heineken Experience. We took some photographs throughout the day but by far my favorites are the ones we took at the brewery – you should definitely check them out. I would like to close this mega-long blog by thanking everyone who made this second-year MEMS Executive Congress Europe a great success from my fabulous MIG Team, to the MIG Governing Council, to the Congress EU Steering Committee, to the AMAZING sponsors (especially those top tier ones who are sponsoring all year long – we love you), the keynotes, the speakers, the attendees (especially the press who attended and those who have posted great stories – hooray!), our fantastic conference organizers at PMMI, and our sister conference folks at Smart Systems Integration. THANK YOU ALL.

Karen’s blog from MEMS Executive Congress: Part 1

There were many things that impressed me from hosting the second MEMS Executive Congress Europe – and it wasn’t the cold and snow (though it was chilly!). What struck me the most was how lively, engaged and intelligent the conversations were, not amongst the panelists but between the audience and the panelists. Often, Europeans can be conservative and reserved in conferences, but not this year In fact my favorite quote from one of the panelists was: “when I agreed to this join this panel I didn’t know I would be joining a religious war.”

MEMS Executive Congress Europe 2013The morning definitely didn’t start off with an aggressive tone as the elegant Ralf Schnupp, Vice President Segment Occupant Safety & Inertial Sensors, Continental served as our keynote. He focused his discussion on future trends in automotive with an overview of the megatrends affecting: safe mobility, clean power, intelligent driving, global mobility and most importantly, safety, with a goal of zero fatalities and accidents (WOW). He spoke of the challenges of complex sensor systems as well as the requirements of such systems. What stuck with me was his statement that “we don’t need more sensors, we need more robust, secure and safe MEMS/sensors.” For sensors I think he’s onto something (because it’s about the smart sensor integration and the software); although when I tried out that theory later that week at our sister-conference, Smart Systems Integration, I was completely shot down (ha!).

After Schnupp’s keynote came the consumer panel moderated very capably by Dave Thomas, Marketing Director, Etch Products, SPTS Technologies. Panelists included: Paul Buijs, General Manager, Bruco Integrated Circuits bv; Robin Heydon, Global Standards – Research and Innovation Group, CSR; and Joel Huloux, Director – Standardization and Industry Alliances, STMicroelectronics. You can probably tell from two of the four titles that the panel talked A LOT about standardization. And yes that was by design, as it’s an important topic that the MEMS industry has been working on and partnering with groups like MIPI Alliance (which Joel chairs).
MEMS Executive Congress Europe 2013

Joel brought a good perspective to the panel because he’s not a MEMS guy; he’s really an OEM/end-user that having spent over a decade with handset company Erikson (I want to say 20 years but don’t quote me) and is now with ST, because of the ST/Erickson joint venture. He said that MIPI aims to create specifications for mobile interfaces and recently became interested in MEMS (and joined an important partnership with MEMS Industry Group) because mobile devices add at least two new MEMS each year. True, but the question remains, what are you going to standardize? And with that question, thus opened a little bit of the holy war amongst the panel and the audience. Clearly it’s an important hot button issue.

When asked about the future of consumer electronics, the panelists all felt that its market strength would continue. Robin felt the most important impact on the world would be the Internet of things as well antenna switching (he does work for CSR after all). He also felt that the next move would be towards peripherals such as the smart watch – while Paul envisioned a future where we’d all have a “doctor in a watch” as the next killer app, enabled by MEMS.

Next up was the automotive panel moderated ably by Marc Osajda, Director, Pressure Sensor Business Unit, Freescale Semiconductor – Germany. With panelists: Frédéric Breussin, Business Unit Manager, MEMS & Sensors, Yole Développement; Pietro Perlo, Vice President Torino E-District, Interactive Fully Electrical Vehicles; and Jan Peter Stadler, Senior Vice President of Engineering Sensors, Automotive Electronics Division, Robert Bosch GmbH. What surprised me about this panel is how quickly the panelists started talking about electric bicycles (e-bikes). I actually had to check with Ralph Schnupp, who was sitting next to me, to confirm that was indeed what Pietro had started the panelists discussing.
MEMS Executive Congress Europe 2013

Marc quickly moved them back to automotive and it was actually quite comical to watch – Pietro and Jan Peter were sort of like the odd couple – both representing opposite sides of the spectrum of automotive. While Pietro focused on totally electric vehicles (including bikes!),Jan Peter averred that the automobile would evolve, but even by 2020 the majority of cars will still be run by combustible engines. Frédéric was well placed as a market analyst to give perspective on current uses of MEMS and sensors in applications such as night vision, heads up displays as well as efforts to reduce emissions, increase comfort and increase safety. What was also clear from all the panelists was that the consumer world is driving more and more of the automotive world; which is good for technology, but bad for pricing.

The best part of the panel was when Marc asked each panelist to describe what his car would look like in 2025. Frédéric said he’d finally give in and buy a hybrid, Jan-Peter said he wasn’t sure what kind of engine but he’d definitely want a car big enough to hold the wine he’d drive back from Romania and carry his e-bike to all the places he likes to use them (in the mountains). Lastly, Pietro stole the show when he said he’d be using a flying an electro-mobility flying car: “this is a possibility because we are MEMS!”

I’ll leave you hanging there, wanting to hear more of the excitement and challenging conversations at MEMS Executive Congress Europe 2013. A teaser: The next panel was MEMS in Energy, which discussed energy harvesting MEMS in depth, and as you can imagine, the opinions varied widely, to put it mildly. Soon, I’ll also describe to you the MEMS in Medical, focused on Aging panel which challenged us all to think more about quality of life issues and what more we can do with MEMS to enable a better world. So stay tuned, I’ll post my next blog soon.

Building a virtual gyro

Originally posted by Michael E Stanley of Freescale Semiconductor in The Embedded Beat on Mar 12, 2013

In Orientation Representations Part 1 and Part 2, we explore some of the mathematical ways to represent the orientation of an object. Now we’re going to apply that knowledge to build a virtual gyroscope using data from a 3-axis accelerometer and 3-axis magnetometer. Reasons you might want to do this include “cost” and “cost”. Cost #1 is financial. Gyros tend to be more expensive than the other two sensors. Eliminating them from the BOM is attractive for that reason.  Cost #2 is power. The power consumed by a typical accel/mag pair is significantly less than that consumed by a MEMS gyro. The downside of a virtual gyro is that it is sensitive to linear acceleration and uncorrected magnetic interference. If either of those is present, you probably still want a physical gyro.

So how do we go from orientation to angular rates? It’s conceptually easy if you step back and consider the problem from a high level. Angular rate can be defined as change in orientation per unit time. We already know lots of ways to model orientation. Figure out how to take the derivative of the orientation and we’re there!

In our prior postings, we’ve discussed a number of ways to represent orientation. For this discussion, we will use the basic rotation matrix. Jack B. Kuipers has a nice derivation of the derivative of direction cosine matrices in his “Quaternions and Rotation Sequences” text – one of my most used textbooks.  It makes a good starting point.  Paraphrasing his math:

Let:

  1. vf = some vector v measured in a fixed reference frame
  2. vb = same vector measured in a moving body frame
  3. RMt = rotation matrix which takes vf into vb
  4. ω = angular rate through the rotation

Then at any time t:

  1. vb= RMt vf

Differentiate both sides (use the chain rule on the RHS):

  1. dvb/dt  = (dRMt/dt) vf + RMt(dvf /dt)

Our restrictions on no linear acceleration or magnetic interference imply that:

  1. dvf/dt = 0

Then:

  1. dvb/dt  = (dRMt/dt) vf

We know that:

  1. vf = RMt-1 vb

Plugging this into (8) yields

  1. dvb/dt  = (dRMt/dt) RMt-1 vb

In a previous posting (Accelerometer placement – where and why) , we learned about the transport theorem, which describes the rate of change of a vector in a moving frame:

dvf/dt = dvb/dt – ω X vb

Those who take the time to check will note that we have inverted the polarity of the ω in Equation 11 from that shown in the prior posting.  In that case ω was the angular velocity of the body frame in the fixed reference frame.  Here we want it from the opposite perspective (which would match gyro outputs).

And again,

  1. dvf/dt = 0 so
  2. dvb/dt = ω X vb

Equating equations 10 and 13:

  1. ω X vb = (dRMt/dt) RMt-1vb
  2. ω X = (dRMt/dt) RMt-1

where:

  1. 0 z ωy
    ω X = ωz 0 x
    y ωx 0

Going back to the fundamentals in our first calculus course and using a one-sided approximation to the derivative:

  1. dRMt/dt = (1/Δt)(RMt+1 – RMt)

where Δt = the time between orientation samples

  1. ωb X = (1/Δt)(RMt+1 – RMt) RMt-1

Recall that for rotation matrices, the transpose is the same as the inverse:

  1. RMtT = RMt-1
  2. ωb X = (1/Δt)(RMt+1 – RMt) RMtT

Equation 15 is a truly elegant equation.  It shows that you can calculate angular rates based upon knowledge of only the last two orientations.  That makes perfect intuitive sense, and I’m ashamed when I think how long it took me to arrive at it the first time.

An alternate form that is even more attractive can be had by carrying out the multiplications on the RHS:

  1. ωb X = (1/Δt)(RMt+1 RMtT – RMt RMtT)
  2. ωb X = (1/Δt)(RMt+1 RMtT – I3×3)

For the sake of being explicit, let’s expand the terms.  A rotation matrix has dimensions 3×3.  So both left and right hand sides of Eqn. 22 have dimensions 3×3.

  1. (1/Δt)(RMt+1 RMtT – I3×3)  = (1/Δt) W
  1. 0 W1,2 W1,3
    W = RMt+1 RMtT – I3X3 = W2,1 0 W2,3
    W3,1 W3,2 0

The zero value diagonal elements in W result from small angle approximations since the diagonal terms on RMt+1 RMtT will be close to one, which will be canceled by the subtraction of the identity matrix.  Then:

  1. 0 z y 0 W1,2 W1,3
    ω X = z 0 x =  (1/Δt) W2,1 0 W2,3
    y x 0 W3,1 W3,2 0

and we have:

  1. ωx= (1/2Δt) (W3,2 – W2,3)
  2. ωy= (1/2Δt) (W1,3 - W3,1)
  3. ωz= (1/2Δt) (W2,1 - W1,2)

Once we have orientations, we’re in a position to compute corresponding angular rates with

  • One 3×3 matrix multiply operation
  • 3 scalar subtractions
  • 3 scalar multiplications

at time each point.  Sweet!

Some time ago, I ran a Matlab simulation to look at outputs of a gyro versus outputs from a “virtual gyro” based upon accelerometer/magnetometer readings.  After adjusting for gyro offset and scale factors, I got pretty good correlation, as can be seen in the figure below.

image001.gif

You will notice that we started with an assumption that we already know how to calculate orientation given accelerometer/magnetometer readings.  There are many ways to do this.  I can think of three off the top of my head:

  • Compute roll, pitch and yaw as described in Freescale AN4248.  Use those values to compute rotation matrices as described in Orientation Representations: Part 1.  This approach uses Euler angles, which I like to stay away from, but you could give it a go.
  • Use the Android getRotationMatrix [4] to compute rotation matrices directly.  This method uses a sequence of cross-products to arrive at the current orientation.
  • Use a solution to Wahba’s problem to compute the optimal rotation for each time point.  This is my personal favorite, but I think I’ll save further explanation for a future posting.

Whichever technique you use to compute orientations, you need to pay attention to a few details:

  • Remember that non-zero linear acceleration and/or uncorrected magnetic interference violate the physical assumptions behind the theory.
  • The expressions shown generally rely on a small angle assumption.  That is, the change in orientation from one time step to the next is relatively small.  You can encourage this by using a short sampling interval.  You should soon see an app note that my colleague Mark Pedley is working on that discards that assumption and deals with large angles directly.   I like the form I’ve shown here because it is more intuitive.
  • Noise in the accelerometer and magnetometer outputs will result in very visible noise in the virtual gyro output.  You will want to low pass filter your outputs prior to using them.  Mark will be providing an example implementation in his app note.

This is one of my favorite fusion problems.  There’s a certain beauty in the way that nature provides different perspectives of angular motion.  I hope you enjoy it also.

References

  1. Freescale Application Note Number AN4248: Implementing a Tilt-Compensated eCompass using Accelerometer and Magnetometer Sensors
  2. Orientation Representations: Part 1 blog posting on the Embedded Beat
  3. Orientation Representations: Part 2 blog posting on the Embedded Beat
  4. getRotationMatrix() function defined at http://developer.android.com/reference/android/hardware/SensorManager.htmlWikipedia entry for “Wahba’s problem”
  5. U.S. Patent Application 13/748381, SYSTEMS AND METHOD FOR GYROSCOPE CALIBRATION, Michael Stanley, Freescale Semiconductor

Preview Blog of MEMS Executive Congress Europe 2013

Amsterdam is THE place to be for the MEMS industry on 12 March!
Karen Lightman, Managing Director, MEMS Industry Group

The keynote address at last year’s MEMS Executive Congress Europe stated: “MEMS is only limited by the imagination.” MEMS Industry Group (MIG) took that sentiment to heart, and organized a 2013 EU Congress chock full of interesting keynotes, panels, dialogue, and camaraderie.  We invited some of the top European companies using and commercializing MEMS to share their insight and imagination on the future of MEMS applications in consumer products, automotive, medical, and energy.  If you haven’t already, I strongly encourage you to register now.

On the morning of 12. March, our keynote speaker,  Ralf Schnupp, VP Segment Occupant Safety & Inertial Sensors of Continental Automotive GmbH, will present “Future Trends in Automotive — Smart Systems and Sensors.” I am extremely honored to have Dr. Schnupp as our keynote; he is extremely well respected in the industry and I know that he will open the Congress in a big and impressive way. In his keynote, he plans to present a vision of the future of automotive that is very macro/global in its perspective with a balance of “enhanced safety, environmental protection, increased connectivity, and affordable vehicles.”

After Dr. Schnupp’s keynote we will have a series of panels focused on MEMS in Consumer, Energy, Automotive and Medical. We’re changing things up a bit – making things a bit more Euro – I guess. I could write an entire blog just on the panels but I’d rather not – as I’m focusing mainly on the keynotes today….but let’s just say that if you’ve ever been to a Congress before, you know we have a “recipe” for success. This year is no different. We have put together a healthy mix of moderators and panelists sprinkled with a little bit of controversy to make things interesting.  Each panelist will bring his own unique perspective  on the critical issues affecting the business of MEMS.

It’s been said that Europe provides a better environment for spawning MEMS innovation. So I look forward to hearing from our panelists who are a great mix of end-users, academics, analysts and industry leaders who will share their visions on the success and remaining challenges to MEMS commercialization success. Some of the inventive topics our panels and keynotes will address are:

  • Standardization has played an important role in propelling growth in the consumer electronics industry – but what about MEMS? What progress has been made and what challenges remain? 
  • What role will MEMS play in the car of the future and how might sensor fusion drive new applications? 
  • How do MEMS advance quality of life now and in the future, from chronic disease management to sports rehab?
  • How are MEMS helping alternative energy adoption in Europe and when will MEMS be commercialized in energy harvesting for smaller consumer applications?

Our afternoon keynote will be Renzo Dal Molin, Advanced Research Director SORIN CRM within Cardiac Rhythm Management business unit, SORIN Group. Dr. Dal Molin is again an extremely well known and respected leader in the field of cardiac medical research and technology.  Dr. Dal Molin’s keynote is entitled “Vision for Implanted Medical Devices Healthcare Solutions and Technical Challenges” and will review how the market for microelectronic implants is growing phenomenally. He will share his vision for this industry and the main drivers of growth, as well as the challenges that lay ahead. I am sure our heads will be buzzing after his keynote and the conversation will take us all the way to our dinner at a place that I’ve always wanted to visit: the Heineken Brewery. Oh yes, we are having a strolling dinner at the world-famous Heineken Experience, where, as I have found myself saying “they serve food to accompany the beer.” We will have fun. That is for sure.

I am obviously giving you just a sneak peak – so for complete details, you need to check out our full agenda that begins on 11. March with a dessert reception. Yes, it might have been the MIG staff’s idea to have plenty of desserts on hand (perhaps you’ve heard we like chocolate?); but we realized after last year’s inaugural EU Congress that most of our attendees were hanging out in the conference hotel bar anyhow, so we might as well make it an official party.

But back to what makes the Congress so unique – and why we’ve successfully held the US version for so many years (it will be nine years, this November 7-8 in Napa!) and why we are returning to Europe for a second year. MEMS Executive Congress by definition is not a technical conference. It is not a tradeshow. This is a business-based, senior-level, executive conference where commercialization, revenue, and success stories dominate the discussion. As Rich Duncome of HP stated a few years back after delivering his keynote, the Congress is like “networking on steroids.”

In my very humble (and oh so slightly biased) opinion, there is only one place in Europe where global industry luminaries will be talking about where MEMS technology is growing, based on real experiences and real time data.  And there is only one place where you can meet them.  This compelling one-day event is a MUST for entire the MEMS supply-chain.  And oh, have you registered yet for The MEMS Executive Congress Europe?  You don’t want to miss it.

MEMS and Concussions

By Karen Lightman, Managing Director, MEMS Industry Group

I am a mom, first and foremost. Right now I am an angry mom, because I have a daughter with a concussion, caused by an accident that was no fault of her own. And because I am a mom who works with MEMS
(MicroElectroMechanicalSystems), I have started thinking about how MEMS might have prevented, as well as detected her concussion sooner.

First let me back up and tell you the story of what happened because I think it’ll help you understand my frustration. I have been a skier most of my life, and since we started skiing as a family three years ago, my two girls (ages eight and 11) have become great skiers, practicing safe and controlled skiing. And yes, the whole family wears helmets.

Recently we went skiing in Western PA. And while I will spare you the gruesome details, as you can see from the picture I am sharing with you, our ski trip did not end well. Basically my eight-year-old daughter was hit by the equivalent of a 225-pound out-of-control freight train on skis, as he snowballed down the mountain and took out my daughter. Now my daughter has near-constant headaches, is tired most of the day, can’t read without pain and will likely miss up to a month of school.

Ski patrol did a good job of assessing her on the mountain, and on the day of the collision she showed no signs of concussion. Her symptoms only started the next day when she fell asleep in class ten minutes into the school day. Only later did I learn that this is quite common, complicating the detection and diagnosis of concussion. In fact there is a lot of confusion when it comes to concussion and that’s what got me thinking about MEMS in many ways.

Accident Prevention – MEMS Motion Sensors

First I started thinking about the idiots that caused the accident. (There were two of them who collided and then one took out my daughter.) With MEMS motion sensor technology like that developed by Xsens and Movea, I envision myself as “vigilante ski mom” seeing lunatic skiers or inebriated skiers. When I see them, I would tag them with a motion sensor that can recognize gestures and would wirelessly send data to ski patrolalerting them when the skier is exhibiting inexperienced skier gestures and on a double-black diamond.

Watch this Xsens video to get a sense of what I am talking about. Then watchthis video of Movea’s motion sensor technology featured by Venture Beat at CES to see why I think this could work – maybe even by putting sensors into ski lift tickets. Think about it, when you buy a lift ticket, you agree to the “skier responsibility code” – which means you will ski at your level and won’t mow down other skiers; MEMS technology developed by Movea and Xsens could help enforce it.

Concussion Detection and MEMS 3-Axis, High-G MEMS Accelerometers

Then I rememberedthe fantastic panel I moderated at Design West 2012 that featured one of my favorite MEMS gurus, Rob O’Reilly of Analog Devices. Rob played a pivotal role in the Head Impact Telemetry (HIT) System with ADI accelerometers inside, used to record on-field head impact exposure during helmeted activities, part of anongoing study with the National Institutes of Health that began in 2002. The work that Rob and his colleagues at Analog did to better understand the impact on the head (not just to the helmet) has led to changes in many sports including hockey, lacrosse and football as well as legislative changes for states such as Massachusetts. But the challenge is still diagnosing concussionafter the hit.

And here’s a not-so-fun fact:  Did you know that after football players, girls’ soccer players are second most likely to get concussions? I am not sure how we’re going to help those soccer players, but with enough industry ingenuity, I am hopeful that we will figure something out.

So again I go to MEMS to help detect a “concussion-worthy hit to the head.” Thankfully there are a few examples where we are seeing an adoption of MEMS technology in sports equipment, including football helmets and mouthguards,such as X2 Impact and i1 Biometrics.The I1 Biometrics’mouthguard is state-of-the-art because it provides a “solution from inside the players head from the inside out” through a multi-function approach: impact detection; data transition; notification and alerts (straight to mom’s smartphone);  and the athlete assessment, by which the system provides tools to assess the athlete’s ability to return to play in a game (or ski). Assessment of injury, post-impact is really critical, but you need to have a baseline upon which to compare it in order to really determine the damage to the brain.

Baseline assessment is key, and fortunately live minutes away from a world-class concussion center, theUniversity of Pittsburgh Medical Center (UPMC) Sports Medicine Concussion Program; these are the guys who took care of the Penguins’ Sidney Crosby when he had his concussion two years ago. The UPMC Sports Medicine Concussion Program pioneered ImPACT™ (Immediate Post-concussion Assessment and Cognitive Testing)–“the mostwidely used neurocognitive testnow mandated by the NFL, NHL, and roughly 6,000 high schools and colleges in the United States.”My daughter is now under treatment by these guys and had a baseline ImPACT test.This is important because statistically she is now more likely to get another concussion and it’ll help us track her progress as she regains her brain function.

Now it’s Your Turn

But isn’t a shame she had the concussion in the first place and that it was untreated until 24 hours after the accident? I just keep thinking that with MEMS technologies I’ve described in this blog, that NEXT TIME a similar situation might not result in another concussion. So I encourage you to visit the hyperlinks in this blog – do the research – mine that swath of land that is an opportunity to help find ways to use MEMS’ enabling technology to embed it into ski tickets or workout gear or ski helmets.Let’s reduce the chance of injury in skiing or other sports you love; especially for children. Let’s reduce the chance of freight-trains taking out eight-year olds on ski mountains, and let’s improve the world through MEMS. Let’s find ways, through MEMS to prevent injuries and then once in an accident to assess and detect injuries much faster and accurately.Will you join me?

MEMS Enabling a Health & Medical Revolution

By Karen Lightman, Managing Director, MEMS Industry Group

One of the most exciting things lately about being director of the MEMS Industry Group (MIG) is feeling the slow and powerful build of momentum that precedes a flurry of wins for MEMS technology in health and medical applications. Someday soon many consumers will use MEMS to monitor and maintain their health on a daily basis.

What’s driving this revolution in health and medical devices? Beyond the prevalence of wireless networks — which is a key enabler — there is a convergence of factors that bring MEMS into this space. MEMS miniaturizes, and it improve safety and reliability. It also provides an integrated solution. Alone on an armband or embedded in a T-shirt, sensors are just a bunch of sad, lonely chips. But wirelessly connect these sensors (including MEMS) via Bluetooth to a cloud computing network, as well as to social networks such as Facebook, and these sensors open up a huge world of opportunities for health and medical providers, designers, integrators, suppliers, and innovators.

Consumers will be the winners here, with more choices and the ability to monitor and maintain their own health, medical treatment, and drug therapies. They will demand non-intrusive monitoring, which is the main reason that the market for wearable wireless sensors (including MEMS) is expected to grow to 400 million devices by 2014.

The time is right for MEMS. The top two healthcare issues in the US are controllable by lifestyle changes (Type II diabetes and heart disease). These are lifestyle changes that consumers could and will control through intelligent sensors that give them reliable, usable information on which their doctors can also rely. And while they may not know it, by demanding accurate, real-time diagnostics and simpler dosing — while caring more about their overall health — consumers are inadvertently creating a path for MEMS to play a bigger role in their suite of medical solutions.

There are already numerous MEMS-based products that blur the line between the consumer and medical markets. Here are a few of my favorite examples:

  • Bodymedia FIT System acts as a “personal GPS” empowering consumers to monitor their overall fitness — measuring the intensity of their workouts and also the quality of sleep, an important factor in weight loss.
  • LumoBack, a wearable device that uses sensor and biofeedback to empower consumers to improve their posture, reduce back pain, and improve their overall quality of life.
  • Proteus Digital Health Feedback System gives consumers the ability to monitor and manage medication and physiologic data.

As we forge ahead with wirelessly connected health and medical apps, we must also grapple with medical privacy. Groups like the XPRIZE Foundation, which is helping lead this revolution of wireless digital, MEMS-enabled health and medical through their Qualcomm Tricorder XPRIZE and Nokia Sensing X Challenge, is embracing this issue. We also need you — the design community — to come up with the next new application of a health/medical product that may not cure cancer, but will help a cancer patient manage her pain as she suffers through radiation treatments. Or maybe you’ll design ______ (fill in the blank with your imagination and your engineering talent).

From the Freescale Blog: Orientation Representations: Part 2

Originally posted by Michael E Stanley in The Embedded Beat on Jan 23, 2013

In Orientation Representations: Part 1, we explored the use of rotation matrices and Euler angles.  At the end of that discussion, I alluded to the fact that there might be more efficient ways of describing rotations.  Let’s start with the rotation of a simple rigid body (in this case a cylinder) as shown in Figure 1.  Here, the cylinder is rotated such that a point on its surface originally at “A” is rotated to point “B” in space.

Rigid Body Rotation

Figure 1: Rotation of a rigid body such that a reference point moves from “A” to “B”

For this simple case, I’ve kept the axis of rotation along the vertical axis of the cylinder as shown in Figure 2.  But that is not a requirement for the underlying mathematics to work.  So long as we have a rigid body, we can always describe the rotation in the manner that follows.

rotation1.png

Figure 2: Overlay of Cartesian Coordinates onto System of Figure 1

Figure 3 deals with the same rotation, but focuses on the fact that we have a rotation plane that is perpendicular with the axis of rotation.  The movement of the cylinder is a rotation equal of angle α, about the axis of rotation, where the point of interest is constrained to lie within the rotation plane.

rotation2.png

Figure 3: Looking at Just the Rotation Plane and Axis of Rotation

The rotation is fully described by the three components of the normalized rotation axis and the rotation angle α, which may be in radians or degrees, depending upon the system in use.  As an example, I recently did some OpenGL ES graphics programming.  This system is very popular on portable devices.  I’m using it to program demos for Android, for later porting to iOS.  In OpenGL ES, you build up 3 dimensional objects as a collection of triangles, which can then be offset and/or rotated to change perspective.  As an example, our cylinder might be crudely drawn as shown in Figure 4.

cylinder.gif

Figure 4: OpenGL ES Drawing of a Cylinder

In this case, I’ve modeled the top and bottom of the cylinder with 6 triangles each, and the other side is modeled using a total of 16 triangles arranged in a strip.  OpenGL ES is optimized to draw such structures efficiently, and it is possible to then “render” textures onto the drawn surfaces.  What’s really neat is that once drawn, we get a reasonable approximation of the cylinder of Figure 1 simply by doing a -30 degrees rotation about the Z axis (presumed to be out of the page) using a single OpenGL ES instruction:

   gl.glRotatef(-30.0f, 0.0f, 0.0f, 1.0f);

At this point, you’re probably thinking: “Yeah, that makes sense, but how does it work at the math level?”  This is the where I need to introduce the concept of a quaternion.  Conceptually, a quaternion encodes the same axis and angle as above. But for mathematical reasons it deals with 1/2 of the rotation angle as shown below.

rotation3.png

Figure 5: System of Figure 4 in Terms of Quaternion Components

Before overwhelming you with the underlying math, you should know that unless you are planning to implement your own quaternion utility library, you only need to know a few key points:

  1. It takes four numbers to fully describe a quaternion (commonly q0 through q3).
  2. Not all quaternions are rotation quaternions.  Rotation quaternions have unit length (q02 + q12 + q22 + q32 = 1).  The discussion below will be restricted to rotation quaternions.
  3. These same rotations can be described using Euler angles, rotation matrices, etc. as discussed in the previous posting.  It is possible (and common) to translate between formats and use multiple formats.  Rotation matrices have the advantage of always being unique.  Euler angles are subject to gimbal lock, and should not be used for internal calculations (only input/output of results).
  4. You can rotate a vector V using a quaternion q using the equation: W = qVq* (quaternion products and complex conjugates are defined later)
  5. A sequence of rotations represented by quaternions q1 followed by q2 can be collapsed into a single rotation simply by computing the quaternion product q=q2q1 and then appling the rotation operator as above.

I will be presenting the mathematical definition first, and without proof.  If you really, REALLY want to know the underlying theory, let me suggest that you pick up a copy of Jack Kuiper’s excellent text: Quaternions and Rotation Sequences.  This appears to be (by far) the most extensive treatment on the topic, even while remaining very readable.

Notice that rotation quaternions deal with α/2, not α. We can define a rotation quaternion “q” in one of several equivalent fashions

q = (q0, q1, q2, q3) (Eqn.1)
q = q0 + q, where q = iq1 + jq2 + kq3 (Eqn. 2)
q = cos(α/2) + u sin(α/2), where u is the vector axis of rotation (Eqn. 3)

I use the quaternion form where q0 = cos(α/2).  Some texts will reorder the quaternion components so that the vector portion q is contained in q0-2 and q3 = cos(α/2).  Be sure you understand which form your text/software library supports.

Quaternions are a form of hyper-complex  number where instead of a single real and single imaginary component, we have one real and THREE imaginary components (i, j & k).  Rules for these imaginary components are:

i2 = j2 = k2 = ijk = -1 (Eqn. 4)
ij = k = -ji (Eqn. 5)
jk = i = -kj (Eqn. 6)
ki = j = -ik (Eqn. 7)

Two quaternions, p and q, are equal to one another only if the individual components are equal.   You add two quaternions by adding the individual components.  If

p = p0 + ip1 + jp2 + kp3; and (Eqn. 8)
q = q0 + iq1 + jq2 + kq3 (Eqn. 9)

Then

p + q = (p0 + q0) + i(p1+q1) + j(p2+q2) + k(p3+q3) (Eqn. 10)

The addition operation commutes.  That is p+q = q+p.  Multiplication of a quaternion by a scalar real number is trivial, just multiply each of the four components by the scalar.  Multiplication of two quaternions is NOT so trivial:

pq = p0q0 – p.q + p0q + q0p + p x q (Eqn. 11)

Multiplying one quaternion by another quaternion results in a third quaternion.  Notice that the 1st two components (p0q0 – p.q) makes up the scalar portion of the result, and the last three (p0q + q0p + p x q) comprise the vector portion.  The quaternion product operation is not commutative pq≠qp. Order matters.  Multiplication of two quaternions includes scalar, cross product and dot product terms.  Unless you are writing your own quaternion library, you are likely never to use the expression above.  Instead, you will use a function that does the quaternion multiplication for you.

The complex conjugate of

q = q0 + iq1 + jq2 + kq3 is q* = q0 – iq1 – jq2 – kq3 (Eqn. 12)

Related to this, we have

(pq)* = q*p* (Eqn. 13)
q+q* = 2q0 (Eqn. 14)
q-1 = q* for any unit quaternion (Eqn. 15)

Eqn. 15 is interesting.  If you think of a quaternion as a rotation operator, it says you can reverse the sense of rotation by inverting the axis of rotation.  Given our usual standard of using the Right Hand Rule to describe the polarity of rotations, this makes perfect sense.  Reversing the direction of the axis is equivalent to reversing the direction of rotation.

Another interesting take on the above is that rotation quaternions are not unique:

q = -q (Eqn. 16)

Any rotation quaternion can be multiplied by -1 and still result in the same rotation!    That’s because we reversed both the angle AND the axis of rotation (which then cancel each other).  It is conventional therefore to remove the ambiguity by negating a rotation quaternion if its scalar component is negative.

At this point, you are surely wondering why in the world you might, or might not, choose to use quaternions instead of rotation matrices.  Here’s a brief summary of the pros and cons:

Topic Quaternion Rotation Matrix
Storage Requires 16 bytes of storage in single precision floating point (4 elements at 4 bytes each) Requires 36 bytes of storage (9 elements at 4 bytes each)
Computation (for 2 sequential rotations) 4 elements each requiring 4 multiplies and 3 additions = 28 operations 9 elements, each requiring 3 multiplies and 2 additions = 45 operations
Vector rotation Rotating a vector by pre- and post-multiplication of quaternion requires 52 operations Rotating a vector via rotation matrix requires 15 operations (3 elements each requiring 3 multiplies and 2 additions)
Discontinuities Generally, we force the scalar part of the quaternion to be positive, which can cause a discontinuity in the rotation axis (it flips). None
Ease of Understanding Generally takes a lot of study to understand the details Easily understood by most engineers
Conversion From rotation matrix =
m11 m12 m13
m21 m22 m23
m31 m32 m33

we have:

q0 = 0.5 sqrt(m11 + m22 + m33 + 1)

q1 = (m32 – m23) / (4q0)

q2 = (m13 – m31) / (4q0)

q3 = (m21 – m12) / (4q0)               (Eqn. 17)RM =

2q02 – 1 + 2q12 2q1q2 – 2q0q3 2q1q3 +2q0q2
2q1q2 + 2q0q3 2q02 – 1 + 2q22 2q2q3 – 2q0q1
2q1q3 – 2q0q2 2q2q3 + 2q0q1 2q02 -1 + 2q32

(Eqn. 18)

Equations 17 and 18 are consistent with regards to direction of rotation.  If instead of rotating a vector in a fixed frame of reference, you rotate the frame of reference iteself, you will need to use the transpose of Eqn. 18 and invert q1, q2 and q3 in Eqn. 17.

Returning to the quaternion rotation operator W = qVq* , note that V needs to be expressed as a quaternion of the form [0, vx, vy, vz], and the multiplications are quaternion multiplies as defined in Eqn. 11.  q* is the complex conjugate defined in Eqn. 12.

If you do a lot of graphics or sensor fusion work, you will probably find yourself constantly switching between the various representations we’ve considered.  You’ll find it useful to remember a couple of identities from your high school geometry course:

The Dot Product u . v = | u | | v | cos α (Eqn. 19)

If both u and v are unit vectors, then:

u . v = cos α (Eqn. 20)dot_product.pngThe Cross Productu x v = | u | | v | sin α nspan> (Eqn. 21)

where n is a unit vector perpendicular to the plane containing u and v (the polarity of n follows the right hand rule).

If both u and v are unit vectors, then:

n = u x v / (sin α)     (Eqn. 22)cross_product.png

If you’ve been paying attention, you will see that α is the rotation of u into v about the axis of rotation defined by u x v.  See!  It’s simple! Axis and angle!

References:

  1. Quaternions and Rotation Sequences, Jack B. Kuipers, Princeton University Press, 1999
  2. Euler Angles from the Wolfram Demonstrations Project by Frederick W. Strauch
  3. Diversified Redundancy in the Measurement of Euler Angles Using Accelerometers and Magnetometers, Chirag Jagadish and Bor-Chin Chang, Proceedings of the 46th IEEE Conference on Decision and Control, Dec. 2007
  4. “Euler Angles” at Wikipedia
  5. Orientation Representations: Part 1, Michael Stanley at the Embedded Beat, October 2012

MEMS, iPhone mics, and impressive growth

By Karen Lightman, Managing Director, MEMS Industry Group
Originally posted on EE Times

 

The MEMS industry saw double-digit growth in 2012, is now valued at more than $10 billion by Yole Développement, and is on track to double in market value by 2015. Let’s examine the drivers of this impressive ramp.

First off,  2012 was the year of “Yes! I can finally hear you and you can hear me, too.” Thanks to MEMS, fuzzy cell phone conversations and dropped calls will soon be a thing of the past. It started at CES 2012 with the teardown of Samsung’s Focus Flash Windows smartphone, revealing WiSpry’s  RF MEMS inside.

This was a historic moment for not just WiSpry but for RF MEMS, as it was the first example of RF MEMS in a commercially available consumer product. History continued to be written and revealed through teardowns.

Jeremie Bouchaud of IHS iSuppli disclosed at the MEMS Executive Congress US that the Apple iPhone 5 uses three MEMS mics in the phone, plus a fourth one in the headset. You can read my earlier blog on “making beautiful music” with Analog Devices MEMS mics — one of four suppliers for iPhone 5 — to better understand the technology behind the ‘smart-quality’ sound achieved through MEMS mics.

The convergence of consumer and medical applications, enabled by MEMS technology, marked another landmark moment in 2012. The explosion of health-focused apps shows that consumers are fascinated with tracking their health through their mobile devices.

Continue reading

Follow

Get every new post delivered to your Inbox.

Join 181 other followers