Android Gyro/Accelerometer Refresh Rate

[Colin]

Hi,

(first post!)

Ok, so Oculus Rift DK1 has a dedicated MCU on the Tracker V2 board clocked @ 72MHz, and that gives it a 1KHz refresh rate for the accelerometer and gyroscope values. (right?)

It looks like the Nexus 5 Android cell phone has a chip from the same MPU-6000 family providing its gyro/accel values.

So does anyone know what's stopping Nexus 5 in a Durovis Dive from having the same kind of quality of tracking as a DK1?

I know it probably won't, but I'm just interested to know what the limiting factors are. Like, does Nexus 5 poll the MPU-6000 chip at less than 1KHz..?

Cheers

[MSat]

You can use this app to test the sampling rate https://play.google.com/store/apps/deta ... te.checker

As far as I can tell, there's not a sampling rate limitation inherent in Android, so it depends on the sensor used, and the driver.

The "quality of tracking" also depends on the tracking algorithms (this is particularly tricky with magnetometers), so sensor sampling rate is irrelevant if your sensor fusion implementation sucks.

[Fredz]

So does anyone know what's stopping Nexus 5 in a Durovis Dive from having the same kind of quality of tracking as a DK1?

The Android system most probably.

The Nexus 5 has a 200Hz frequency for sensor reading. See comments there : http://ilessendata.blogspot.fr/2012/11/ ... rates.html

[PalmerTech]

It also depends on the sensor mounting and calibration procedures at the factory, both of which are fairly poor on phones. There is no reason to worry about it for typical phone use.

[Easter6]

This works very well for a 'poor-man's tracker':

http://www.geekbuying.com/item/RC11-And ... 06420.html

little to no lag that I can discern (of course I was testing it on the PC and not a VR headset. Best thing to do would be to use Splashtop remote desktop and use an nVidia GPU to output the video stream over USB (or CAT5 cable -> USB OTG) to your mobile device mounted in a headset. In that scenario there's very little lag. Ultimately, of course, if your headset consists only of a screen (or two) and you can tap in to a direct video feed from the PC, you're golden.)


you can see it in action here:

https://www.youtube.com/watch?v=I1C1hu1PUmw

I've only tested mine out briefly, but I think it'll suffice. I don't mind having a remote strapped to my head, hahah

*there's also the Kainy app for Android (not sure if it's for iPhone). There's both client and server apps. I simply don't have enough grunt on the PC side in terms of CPU to make a proper go of things with Kainy, though (both CPU and GPU will be getting an upgrade very soon, however). But it does have the benefit of being able to utilize the gyro built into your phone, apparently. It also smooths things out if you decrease the quality, which goes some way to negating the 'screen-door effect' that comes with using magnification lenses with a smartphone's display in your headset.

** there is also the Limelight Game Streaming app for Android, which supposedly gives very good results. I, however, know nothing about it, as I don't use Steam nor do I have an nVidia GPU (though I think it's time I switch sides and go nVidia for my next video card purchase).

[Colin]

Thanks for your help, I understand it a lot better now. It's actually not as bad as I thought.

I'm surprised that the sensors are being read as fast as 200Hz - that might actually be fast enough to leave as it is, otherwise I might investigate using the sensors via native code or modifying the OS.

@Easter6: That remote is an interesting potential solution for something else I've got in mind, thanks for the info.

[turilas]

Xperia Z1 have nearly 200hz gyro and accelerometer, magnetometer about 60hz (i dont know if that is good or not)