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From: zoara on 1 Jul 2010 06:44
Will iPhone 4 GPS software be able to make adequate use of the new
gyroscope to make a reasonable estimate to your position when you can't
get a GPS signal (like in a tunnel)?

I'm guessing yes as far as turns go - so if you come out of a tunnel
and, before it re-establishes a GPS fix you immediately turn left
instead of right, it should notice. But noticing when you get stuck in
traffic inside the tunnel amd reacting by slowing your progress on the
map seems less likely.

I know nothing about gyroscopic positioning, though I'm vaguely aware
some built-in sat navs use it in a similar way to above. I think they
also have sensors attached to the wheels which will obviously give a
more accurate estimate, but isn't an option for iPhone apps.

-z-

--
email: nettid1 at fastmail dot fm
From: J. J. Lodder on 1 Jul 2010 07:34
zoara <me18(a)privacy.net> wrote:

> Will iPhone 4 GPS software be able to make adequate use of the new
> gyroscope to make a reasonable estimate to your position when you can't
> get a GPS signal (like in a tunnel)?
>
> I'm guessing yes as far as turns go - so if you come out of a tunnel
> and, before it re-establishes a GPS fix you immediately turn left
> instead of right, it should notice. But noticing when you get stuck in
> traffic inside the tunnel amd reacting by slowing your progress on the
> map seems less likely.
>
> I know nothing about gyroscopic positioning, though I'm vaguely aware
> some built-in sat navs use it in a similar way to above. I think they
> also have sensors attached to the wheels which will obviously give a
> more accurate estimate, but isn't an option for iPhone apps.

The gyroscopes tell you about orientation, not position.
In addition you need accelerometers.
The gyroscope tells you what direction the acceleration is in.
Integrate the acceleration vector twice
and you have your position.
It's called inertial navigation.

So yes, even in a trafic jam in a tunnel
the system can know where it is.
It doesn't depend on extrapolation,

Jan

From: zoara on 3 Jul 2010 19:01
J. J. Lodder <nospam(a)de-ster.demon.nl> wrote:
> zoara <me18(a)privacy.net> wrote:
>
>> Will iPhone 4 GPS software be able to make adequate use of the new
>> gyroscope to make a reasonable estimate to your position when you
> > can't
>> get a GPS signal (like in a tunnel)?
>>
>> I'm guessing yes as far as turns go - so if you come out of a tunnel
>> and, before it re-establishes a GPS fix you immediately turn left
>> instead of right, it should notice. But noticing when you get stuck
> > in
>> traffic inside the tunnel amd reacting by slowing your progress on
> > the
>> map seems less likely.
>>
>> I know nothing about gyroscopic positioning, though I'm vaguely aware
>> some built-in sat navs use it in a similar way to above. I think they
>> also have sensors attached to the wheels which will obviously give a
>> more accurate estimate, but isn't an option for iPhone apps.
>
> The gyroscopes tell you about orientation, not position.
> In addition you need accelerometers.
> The gyroscope tells you what direction the acceleration is in.
> Integrate the acceleration vector twice
> and you have your position.
> It's called inertial navigation.
>
> So yes, even in a trafic jam in a tunnel
> the system can know where it is.
> It doesn't depend on extrapolation,

Would this be reasonably accurate on an iPhone, given that it will be
mounted god-knows-how? Would the sat nav software developers be able to
make reasonable use of this information in practical terms (ie given all
the different ways people might mount their phones)?

And is it likely we'll see this kind of feature? I somehow doubt they'll
think it's worth adding...

-z-

--
email: nettid1 at fastmail dot fm
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