Is that really necessary? Especially considering you're the one making extraordinary claims here...
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Do you really need your iPhone all the time?
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Is that really necessary? Especially considering you're the one making extraordinary claims here...
Yes, since he/she doesn't know what he/she is talking about AND doesn't know when to stop.
Yes, it is.
Because I'm not making extraordinary claims here, it's science, not witchcraft. If you have GPS geolocation on point A, and you went to point B, and recorded every point in between (a path), you know GPS for point B without using GPS.
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Yes, since he/she doesn't know what he/she is talking about AND doesn't know when to stop.
Do you know?
Or you are just pissed you don't have $350?
As others have been trying to tell you, in practice the accuracy is simply not there for anything but trivial examples as a practical matter what you're proposing sounds a lot more like witchcraft than science at this point. It's on you to provide proof that there's even a remote possibility for the Apple Watch to have anything close to this capability.
This is an extraordinary claim, and as such demands extraordinary evidence:
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I do know that a childish personal attack on me doesn't in anyway prove your unproven, unknown and outragusly impossible assertions.
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There is one claim that I'd like to revisit:
The iPhone constantly monitors our speed using the accelerometer?
Lets assume for a minute that this is possible using the accelerometer..
How does the iphone know when it is moving at exactly 0.0 mph? You need a known starting point right? So that any accelerometer readings can be converted to speed based on this starting point?
You cannot use GPS, you can be flipping the phone in your hand and the GPS reading will not change. The accelerometer won't tell you either.
The same question then applies to the aWatch, how does it know when it is moving at exactly 0.0 mph? So all the accelerometer readings on your run can be converted to a distance/speed ?
The iPhone constantly monitors our speed using the accelerometer?
Lets assume for a minute that this is possible using the accelerometer..
How does the iphone know when it is moving at exactly 0.0 mph? You need a known starting point right? So that any accelerometer readings can be converted to speed based on this starting point?
You cannot use GPS, you can be flipping the phone in your hand and the GPS reading will not change. The accelerometer won't tell you either.
The same question then applies to the aWatch, how does it know when it is moving at exactly 0.0 mph? So all the accelerometer readings on your run can be converted to a distance/speed ?
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YES.
That's why they put a M7, to do that, while conserving power.
0 mph = stopped.
When you start moving, the accelerometer registers acceleration, while you move, the accelerometer doesn't register anything, when you stop, the accelerometer registers acceleration in the contrary direction.
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Yes, it's there.
If you don't believe it, then don't believe, I have an example of that in my pocket, it's called the iphone 5S.
No, it's not witchcraft. It's engineering.
My question was how does the device know when it starts moving?
The accelerometer registering acceleration only tells you it is speeding up or slowing down? How do we get the known starting point?
An accelerometer can detect how fast you go from a speed to another speed. So if you are not moving and you suddenly move, the accelerator will detect that and the computer will take that as your starting point. If you integrate acceleration you can get velocity and integrate velocity and you can get position.
There's a smaaaaaaaaaal problem with that, though. Accelerometer is not perfect. 1st, its data is noisy, and the noise is not distributed as a perfect Gauss. 2nd, its update rate is rather crude (only 100Hz). And 3rd, it has unknown biases, and these biases change with time.
1) Noisy data, even centered around perfect value (i.e. bias is precisely zero), after some time double integrating it, will diverge. It's a random walk, Brownian motion. The Brownian particle, on average, travels a distance from the origin proportional to the square root of time (although, if an accelerometer was strapped to it, it would show zero average acceleration). So, the calculated position diverges, although not as dramatically as in 3).
2) Because the update frequency is finate (only 100Hz), all kinds of aliasing artifacts are possible. Suppose, the phone is lying on a table. Passing trucks on the nearby freeway create a vibration, suppose, at 100Hz, and its crests land perfectly on accelerometer's samples. Then each sample gets a "bump" by some value, say 0.05g. In 1s of double integration this produces an error of 0.5m/s^2*1s^2/2 = 0.25m. In 1000s (~15 mins) that error will grow to 0.5m/s^2*1000s^2/2 = 250km. Your phone will "think" that it flew 250 kilometers in 15 minutes. Woa. Of course, parasite vibrations won't stack up that perfectly, and the divergence won't be as dramatic.
3) Each accelerometer (and along each axis) has a bias. Meaning, the current corresponding to deflected mass on a "spring" is not zero when it should be zero. For using phone as an inclinometer, that's not a big problem, because you're not integrating anything. A 0.05g bias will produce a 0.05 radian error in measured angle, or only about 3 degrees. But the same bias, as above, will put you on the Moon (380000km) in only ~10hrs.
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Getting off the impossible, wacky witchcraft Si-Fi fallacy and back to science and the way things actually work.
I like most others always thought the aWatch would provide distance estimation without the iPhone using the OEM Workout app. One thing I had in the back of my mind was, what about biking? Without arm swing biking will not provide sufficient data to estimate distance. Also Apple has added to the aWatch site and while it is a little ambiguous it appears to say you can't get a distance estimation without the iPhone.
Apple says this when only using the aWatch and it doesn't say distance (and of course excludes biking):
Then Apple says this about using your iPhone's GPS. However it does say "more accurately" indicating it does estimate without GPS. Seems a little contradictory.
I like most others always thought the aWatch would provide distance estimation without the iPhone using the OEM Workout app. One thing I had in the back of my mind was, what about biking? Without arm swing biking will not provide sufficient data to estimate distance. Also Apple has added to the aWatch site and while it is a little ambiguous it appears to say you can't get a distance estimation without the iPhone.
Apple says this when only using the aWatch and it doesn't say distance (and of course excludes biking):
Apple said:
Then Apple says this about using your iPhone's GPS. However it does say "more accurately" indicating it does estimate without GPS. Seems a little contradictory.
Apple said:
Really simple. Once you start running, you will have a velocity. When you stop, the accelerometer will detect a negative acceleration and the computer will calculate if you stopped completely or you just decreased your velocity. Let me explain by formula;
Acceleration is equal to a=Dv/t and Dv= Vf-Vi
Dv is the change in speed. Vf is final speed and Vi is initial speed. And t is the time this change took to happen. So if a person goes from 0(in/s) to 60(in/s) in 2 seconds, that's an acceleration of 30(in/s^2).
If you go from 60 (in/s) to 30(in/s) in 3 seconds, you have an acceleration of -10(in/s^2). The negative represents speed decrease.
Now going at 30 (in/s) and after 10 seconds you speed is still 30(in/s). That's an acceleration of 0, and that's how the computer knows you haven't changed velocity.
And finally you are going 30(in/s) and after 30 seconds the accelerometer detects and acceleration of -30(in/s^2). The computer will calculate the final speed (Vf) which is 0 (in/s). That's when the computer knows you stopped.
The accelerometer will constantly work and the computer will know what you are doing respect to time. So it knows when you stop and when you move.
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According to your formula you need a known starting condition, do you not?
How does the device get this?
Regardless if the accelerometer is constantly measured. The device does not know if it is moving when it is switched on or not.
What I think you mean is that what if the person is not moving and therefore the acceleration reports 0 and it might confuse this with the person moving at same speed. That's where it will use GPS. As samiznaetekto said, accelerometers are not exact, they have a lot of noise hence sometimes they are paired with gyroscopes. But for the device to get your exact location, it uses GPS, cellular antennas and accelerometer to get get precise location and the accelerometer helps in defining movement.
Yes that is kind of what I mean.
Devices that do this sort of thing normally have you place the device on a flat surface and press a button to confirm a starting position.
I have used a lot of GPS, IMU(accelerometer and Gyroscope in one Package) in my projects and I would use the data from all of them to get an exact idea of what is going on. However Apple might have a technology that without the need of a gps they can figure out the starting point but we are unaware of that.
Accelerometers/gyro can't be used for complex mapping (like a random meandering run) with any degree of accuracy. In my example of a run you can't say with a straight face (unless you are wearing a tinfoil hat) that an accelerometers/gyro could track this run accurately with every turn matched and be on the same roads and even end at the same point. It is impossible without GPS using any technology know today.
There is no consumer device on the market that uses accelerometers/gyro info for mapping tracks.
If you say yes please provide even one example of a device that can do this. I will buy it* and test it concurrently with my iPhone and a GPS watch.
*Must be a consumer device that can be carried and track dynamic running and cost less than $400.
Apple has and does clearly state that you will need the iPhone's GPS paired to the aWatch to track moment (have you read the info on the Apple Watch site???). Apple has no 'magic' way of determining your lat/long.
This is a pointless discussion about a technology that does't currently exist (other than in theory).
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You should be careful how you use the word impossible. Acceleration can give you more than rate of speed change. It can also give you how much distance you have moved. If you integrate acceleration you get Velocity and integrate it again and you get distance. So from acceleration you get that you moved 100 ft and then using the compass you can find the direction of that 100 ft. A person can move 100ft North then 50ft East and etc. You get a path! The first gen iPod touch didn't have a gps but it could still track your movement on the map!
I'm not saying that the iPhone doesn't use the GPS at all, it does. But since a gps isn't exact at all, they must use the accelerometer to correct the position.
That is not what Tanegashima is saying and you seem to be supporting. I want you or Tanegashima to provide me with one example of one device that tracks dynamic runs accurately WITHOUT GPS involved in anyway. Tanegashima says the aWatch can or will do it and you seem to be supporting his wacky theory.
All I want is ONE example of a device that uses accelerometers/gyro (no GPS) and can track dynamic runs over distance accurately.
Just one is all I'm asking for.
I did say it, the iPod touch first gen! it's a device that didn't have a gps but it could track your movement. It wasn't precise but it could do the job. The GPS serves to verify that the accelerometer is calculating correctly. Hence why it's not impossible but it's not accurate.
For an accurate reading yes a gps is required, but again a GPS without an accelerometer is also useless. How accurate do you think the GPS inside the iPhone is?? i have one that can track 42 satellites and still it has an accuracy of +/- 10m. That's why we use accelerometers.
I'm not supporting anyone's theory. One guy asked how the accelerometer can detect movement and I explained that.
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Fair enough and apologize for jumping the gun. Tanegashima quoted you to support his/her outrages claim. That post also had some personal attacks and has been removed. If interested just go back and read this thread to see the nonsense that was posted by this person.