i want to track how fast my iPhone is moved.
i checked the AceelerometerGraph Example App, where the maximum Amount was about 2.0 (in this app)
i want to know how exactly i can track the speed of my moving iphone. in this example app the maximum amount is reached very fast. Is there a way to get better results ?
Sry for my bad english :( Comment me if you dont know exactly what i mean
I don't know what your question is. The subject doesn't really fit the rest of your "question". It is impossible to detect speed with an accelerometer. You can only measure acceleration. I heard the maximum acceleration that can be detected with the iPhone's accelerometer is approximately 2.5g, but I'm not sure.
Yeah, it's about 2.5G... Unfortunate, I really wanted to build the iphone version of E39. Oh well.
Related
Presume I have two+ iPhones connected to the same server.
Using the sensors built in the iPhone and any possible calculations based on their information, is there any way to tell which direction one phone is from another?
They would be in the same room, so the fluctuation of GPS would not work very well here.
I've tried to model two points on a graph using only their compass readings, but I do not think this will work alone. I could be wrong though.
You could setup a calibration phase in your program where you start each phone in an exact position, and then using the 6 axis motion continually calculate the exact current position (in all 6 axis). But the longer you run that calculation the further from true position you will be and eventually (given a long enough time) one phone could think it's in canada and the other in Mexico.
So It could work for short term spurts if you do a calibration every time you want to start.
There is also the possibility of bluetooth localization, but that would require at least 3 phones and the sharing of positional data between them. Or you could do wifi location, but that would require the same as the bluetooth.
Long story short if you want inches localization it's not going to happen. If you want yards localization it's possible, but not as usable.
As you already mentioned, GPS does not work very well when used inside buildings. Thus, it is not possible to get the direction, as you don't have two reliable positions.
Indoor localisation should be much easier with iOS7 and location beacons .. but this does not help much now.
Is there any way to find the distance between two iPhones without using GPS in iOS??
i am working on finding out the exact distance between two iPhones which are few feet away.
Any suggestion, tutorial/links would be appreciated.
Looking forward for reply...
You could create some sort of sonar type thing. Use bluetooth between the devices to "arrange" a date stamp and emit a sound from one of the devices at the exact time stamp.
On the second device listen for the sound and mark the timestamp that it comes in at.
Then you can work out how long it took to get from one to the other.
I don't know how accurate that would be though.
Or possibly easier would be to emit a sound from one device then when the second device picks it up it re-emits another sound.
Then the first device listens out for the reply and can find the distance between them in time.
The only thing that comes to mind is some sort of audio chirp that you could measure the latency between, but at a few feet apart, I don't know that you'd be able to get the two iPhones synchronized closely enough to be able to take an accurate measurement.
As long as there isn't too much noise, you could pair the devices using bluetooth and use the signal intensity as a measure of distance. This will probably require a lot of trial and error, but I think that without gps it might be your best choice.
You could also go for wifi triangulation if you had enough access points with known locations, but this might be even more inaccurate.
I'm contemplating a casual 3D modeler app for phones. Here's the rough concept sketch: http://versuspad.com/image/3d-modeler.png
Would you think it is possible to program this, or do the Gyroscope and other approaches just not yield the desired data at all?
(I was not sure whether to post this here at Stackoverflow or at programmers.stackexchange.com, but choose the former for now, hope it's correct.)
hmm... well quite innovative.. I must say.. you should have signed an NDA with all the viewers of your post..!!
coming back to the question, yes it is possible to read accelerometer values they way your app demands but the real thing will be the use that data to generate your desired application's output.
Absolute position is the double integral of acceleration. Double integration amplifies noise and starting velocity errors so much, that any 3D model would get stretched way out of shape very quickly, and look nothing like the gestures in space.
This is totally possible with the iPhone. It would more use the Accelerometers than the Gyro, but do-able.
Coding it will be very difficult - but it is possible.
Just search around on Google and Stack Overflow and you might find a few useful ways how to use it. E.g. for gyro and accelerometer
quick question. How accurate is the GPS on the iPhone 4? I ask because I'm working on an enterprise project for a company, and part 2 of it will deal with iDevice development where I have to determine the position of the user. I'd like to know if the GPS is accurate enough to sense the user moving within rooms because the user will have to "tag" sections of the room as they move about it.
Thanks in advance!
P.S. Pressuming that it won't make much of a difference, but the users will actually end up using the iPads, not iPhones, and more than likely the iPad 2 will be out by the time the entire project is completed. I don't know if the iPad 2 will have a better GPS receiver or not, but at the minimum I should use the iPad/iPhone 4 GPS receiver...
Most buildings will not allow reception of an accurate set of GPS signals (if they can be received at all) indoors. The roof/ceiling/floors above are just too thick. Even a lot of trees overhanging a building will degrade the signal from the GPS satellites.
You might have a chance if all the rooms have very large unobstructed windows with no overhangs, and it's the right time of day for several satellites to be in view out that window.
Outdoors, in the clear, the iPhone 4 GPS seems to be very accurate. Sometimes I can walk around my parked car, and see the blue dot in the Maps app follow me in a circle.
I have done some work with a large location data set. My result set is based on cars driving outside and will therefore be, on average, more accurate than those taken inside (based on line of sight to satellites).
For the 650,704 location updates I used in my tests, I found the average accuracy radius was 246m (91m if your remove >1km outliers). 85.1% of updates had an accuracy of less than 100m. So given that your update will not be as accurate as these, I don't imagine you will have much success tracking indoor location changes.
For a further description of my results.
It is very difficult, and most of the time impossible to obtain a GPS signal inside a building. The type of waves used by the GPS (radio waves) are not powerful enough to go through the structure itself.
A simpler and probably cheaper solution would be to give people maybe tags or cards and install some sort of trnasreceiver in each room.
It seems the original question was "how accurate is the GPS on an iPhone 4", which hasn't exactly been answered yet.
I've done lots of testing with the accuracy of the GPS chips in iPhone 4, iPhone 4s, and iPhone 5, and the most accurate reading allowed seems to be ~5 meters, or ~16 feet when you're outside with clear line of sight to the sky. I'm guessing this is a software limitation imposed by Apple to conserve battery.
as I am developing for iPhone, I've just bought an iPhone 4 to test my application which needs to measure the coordinates of my location. I don't have any Internet (3GS, GPRS or whatever...) on my iPhone and the problem is:
1) Without internet I get a 1744m horizontal accuracy, and that's very bad. (I've also tested the accuracy in other applications too, and it is always as bad or worse)
2) With WiFi-Internet I get a 80m horizontal accuracy.
Is that normal? What can I do to improve my coordinates-measurement accuracy?
Thanks in advance for any help.
From my experience you need cellular data reception (3G or Edge) to get an accurate location on any iPhone. With that and a clear view of the sky you should be able to get within a few meters of your actual location.
Yes, this is normal. To improve accuracy, you can move somewhere with a clear view of the sky.
First thing I'd advise is make sure you have a clear view of the sky to get a good satellite signal.
I think that it is becoming somewhat "accepted" that the iPhone's GPS accuracy is somewhat lacking (in comparison to other handhelds)... I had to search through my history, but I remembered reading about this very issue on Hacker News - http://news.ycombinator.com/item?id=1526664.
If you don't want to follow the thread, here is the article directly - http://rnr.davidlokshin.com/post/825290568 .
I learned recently that the phone needs to download a batch of coordinate files in order to make any real sense of the GPS data it picks up. So without an internet connection, GPS service is very poor or possibly completely unavailable.
I'd bet your poor accuracy with WiFi is because you were indoors... That's my guess anyway.