Exercise Tracking Difficult Because Active Accelerometers Fail Intermittently

[#1]

I have an app, Activity Classifier, that uses the handset accelerometers to provide information on activities and total exercise. It automates exercise tracking, classifies activities by type and quantifies aerobic intensity. Live data streamed from an Xperia Arc using the app is displayed in a blog. 

While it is possible to use on the Active it is unfortunately more difficult on the Active than the Arc because the Active accelerometers have a fault that is hard to get around. The problem is that the accelerometers sometimes take quite a while to start sampling when either started or the sampling frequency is changed. Occasionally it can take longer than 90 seconds.  The problem can be seen with the app Accelerometer Frequency. Switch between sampling frequencies and notice that sometimes it switches instantly and sometimes it doesn't.

To minimise battery consumption Activity Classifier acquires data from the accelerometers for 6 seconds out of every 30. If no other app is using the accelerometers they will start and stop every sampling period. On the Active they frequently don't start and the app detects a faulty accelerometer. The app has an option to keep accelerometers on and if this is selected it will work OK but battery consumption goes up a lot. The Active comes with a pedometer app called Walkmate. I can see from the Accelerometer Frequency app that Walkmate keeps the acclerometers running at 50 Hz and running Walkmate at the same time as Activity Classifier will make Activity Classifier work OK as well. Walkmate seems pretty power efficient and uses less than half the power of the market leading pedometer app Accupedo, run in power balanced mode, but it counts a different number of steps.

I'm hoping the next model of the Active or any Android updates on the current model can fix this issue. Is Sony already aware of this issue and are they planning to fix it?

[Markus1]

Thank you for the detailed description of this issue.

I can report this but I need some information from you first. Please give me the following info and I will escalate this.

SW build number: (Settings > About phone)

SI number: (printed behind battery in format SI XXXX-XXXX)

IMEI number: (printed behind battery, 15 digit long and starts with 35 or 01)

Thank you!

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[#3]

The issue is not specific to one handset. It was first reported by Ifor who also contributes here see http://talk.sonymobile.com/people/Ifor?view=overview

As requested the details for the handset I experimented on are:-

SW Build number 4.0.2.A.0.62

SI 1253-6954

IMEI 35851104-009729-1

Model St17a

[Markus1]

Thank you very much. I have now created an internal escalation on this.

I will get back to you when I have received an answer or any feedback worth telling.

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[Ifor]

Information from my device is.

SW Build number 4.0.2.A.0.62

SI 1257 - 6360

IMEI 358510042023958

Model ST17i

Ifor

[#6]

Thanks for that, it is great to be interacting with the Active developers. I've uploaded a new version of our app to the market that improves the handling of the identified problems with the Active accelerometer.  When the accelerometer is not functioning activity is recorded as Unknown and the app no longer closes after accelerometer failure is detected but attempts to recover. See https://play.google.com/store/apps/details?id=com.urremote.classifier .

The Active is brilliantly aimed at Sports and incudes novel sensors i.e. barometer. Android already has two sensors, orientation and acclerometers, that use the same hardware accelerometer sensor. There is an opportunity to introduce another sensor using the accelerometers that would make the Active better for some sporting applications without modifying the Active hardware.  That sensor is a spectral acclerometer sensor that would, among other uses, be very helpful for activity recognition. With data from the microphone, apps can do FFT fine and there are lots that do. There are also some apps that do FFT of the accelerometer data e.g. https://play.google.com/store/apps/details?id=de.bremen.btm.movalyzer and https://play.google.com/store/apps/details?id=com.atriuscreations.seismographis . As well, we are experimenting with FFT analysis of acclerometer data. It is difficult in Android as FFT requires exact intervals between each sample and the Android accelerometer sensor interface does not provide this. It can be good enough but it depends on what the phone is doing at the time. We do quality checks on each sample set before the FFT but this is not an ideal solution.  FFT done in the driver would also be more battery efficient than in the app environment.

Would you consider introducing a spectral acclerometer sensor on future models?