Re: N900 Specifications
 

Cool..good to know...and as I suspected they are pretty big. You would need 3 of them for 3-axis sensing and every cubic millimeter you devote to a new gadget is a cubic millimeter less battery volume.

Well, just because somebody wrote an article doesn't mean it's Providence or even a good idea...the fact that said gyroscopes DIDN'T come with smartphones as predicted should clue you in to that. As for the PS3...it has a gyroscope because they decided they wanted the ability to very precisely measure all 6 axes (it also has accelerometers) at additional cost. A better comparison is the original wii controller. which had accelerometers only (they were trying to keep costs down) and did an exceptionally good job for all but the most precise motion use cases due to the excellent software they wrote for the motion control. The $30 add-on brought gyroscopes to the table for more angular precision...but it *added* to the capabilities that were already there (and it does, in fact, occassionally get out of whack and requires resetting/recalibration) . The reverse would not be true (you couldn't have made a wii controller with just gyroscopes and added the accelerometers later).

So, now we get back to the phone world. Exactly what is it that you hope that your phone could do with a gyroscope that can not be accomplished with the already included accelerometer setup? Maybe I'm just not creative enough to dream up what it is that I'm missing out by only having lateral force sensing in my phone.

:D

Re: N900 Specifications
 

IIRC A gyro is quicker and more precise than a digital compass. Think about it as... a compass is good for orientation, a gyro is good for recording motion (especially the yaw component). A compass will never be as precise as a gyro to tell you how quickly you are turning (ever see those iPhone augmented reality apps ? You moooove theee deviiice sloooowly or it get's jumpy real quick). At the same time the gyro will not be able to tell you which way is North without constant (re)calibration, so they are not drop-in replacements. AFAIK no game controller has gyro(s) *instead* of accelerometer(s), they have gyros *in addition* to accelerometer(s).

Re: N900 Specifications
 

The dual-axis gyro IDG-2000 will be released in October and is 4x4x0.9mm, so about the same size of the thinnest 3-axis accelerometer (the volume ratio is 1.28). I don't know the OEM price. The IDG-1215 was $20 per unit (but per thousands, the price should be much lower). So, I don't think it would really be expensive.

Smartphones are not just phones. They have cameras. And it has been said that gyros help image stabilization.

Re: N900 Specifications
 

Not "really" expensive in terms of absolute price perhaps..but it's added space and power consumption that doesn't get you much in the way of new capabilities that people care about. Paying "something for nothing" is not a winning strategy...it's a solution looking for a problem on this kind of platform.

Accelerometers are typically used for embedded image stabilization. What else you got? :p

Re: N900 Specifications
 

I've been wishing for gyro too, even before reading about the AR craze. In my case I wanted them for augmenting gps data to give higher sampling rate. Inertial navigation, but reset every second by gps updates. Gyro calibration can be done automatically when accelerometers indicate no movement, with data from accelerometers and digital compass.

How useful is a digital compass anyway? i've had a few watches with digital compasses, and they required calibration to work at all, and even then they were nearly useless

Re: N900 Specifications
 

This is not what other people say, see e.g. http://www.photographyblog.com/news/...camera_phones/.

Re: N900 Specifications
 

I said "typically"...yes there are high-end devices that include gyros as well (or will...did you notice the date on that article). Until you get the sensor and optics to match, there's little reason to go that route solely for the purpose of photography since accelerometers can do a pretty fine job by themselves. On a phone like the N86 with its 8MP camera (obviously being marketed towards the photography crowd) or actual single-purpose digital cameras...maybe it would be worth it. On the N900...probably not so much given it is expensive and crowded enough as-is. In any case, one would be FAR better off overall with a more sensitive accelerometer (far more general-purpose) than just throwing in a gyroscope when space and power are limited. /shrug maybe some engineers think the tradeoff is worth it if the price is right.

The only thing a gyro can truly do is add a marginal improvement in performance over an accelerometer in some cases. It doesn't add anything "new" worth talking about in a phone platform. If you are willing to pay more, have less battery life and/or have an even chunkier phone for that marginal improvement in pointing accuracy or image stabilization...then go for it. However, I'd wager 99% of the consumer market out there (myself included) is quite happy with the performance modern solid-state accelerometers can give when coupled with decent software (wii controller being a fine example..yes it can be and was improved later, but it was incredible as-is too). If they get down to next-to-free in terms of actual dollar cost, space requirements, and power draw..then sure...throw them in. At that point why not? As it is, there's just not enough margin of improvement to make it worth it for the vast majority of the consumer phone market.

So again..what else you got?

Re: N900 Specifications
 

Yep, and you've ironically missed the fact that a gryo can be *replaced* by that combination of accelerometers, gps, and digital compass rather than just being there to calibrate it. Just because the iphone's (or your watches) digital compass sucks doesn't mean they all have to. I'd take a "good" digital compass over a gyro (assuming I already have a decent accelerometer and gps anyway) anyday. Far more useful in day-to-day activities than the incremental improvement in angle-change detection that a gyro brings to the table.

And as someone who has written gps-data processing software, I think your ideas on the inertial guidance system needs some more work ;) You're not going to gain anything from trying to update the INS every second with gps....gps just isn't that accurate (at least civilian systems) while moving. You'd be better off just relying on the INS with that rate of update. The rate at which it becomes beneficial to update with gps is related to the INS drift rate..which would need to be calculated against a known course with well-defined waypoints. So, while you're on the right track..there's more to it that you've given credit for.

Re: N900 Specifications
 

A compass is required for augmented reality. To determine where your device is looking at requires 3 dimensions:

- GPS: your location on the world
- Accelerometer: the angle you're holding the device
- Compass: the direction you're looking at

To see this in action, you could try Google Skymap on Android phones. You hold your phone against the starry sky and see the names of the constellations you're pointing at on screen.

Re: N900 Specifications
 

All true. Of course, with a camera, one might be able to calibrate a device by telling it which directions were north/south/east/west...maybe?

Tim