Is there any way to make this kind of app:
you draw a room with precision in the program, put your actual position(where is your phone right now) point in this representation of your room in the app and then when your phone is moving the app would say precisely where it is in the room?
You are going to have issues with most phones because the GPS isn't going to give you a fine enough location for what your trying.
http://www.mio.com/technology-gps-accuracy.htm
Related
I'm trying to find a good way to track location of people in a building. I would ultimately like to be able to create a graphic on demand showing where employees are in a building - which floor (elevation), and where on the floor they are located (lat/lon). I have read that elevation is relative to the WGS84 ellipsoid, not sea level necessarily, which is fine. I can define a baseline of where the first floor is, for example, and then calculate the difference of a person's current location from there. If I understand correctly, the general precision lat/lon for a GPS is as fine as 1m, which should be sufficient for me.
Part of my problem is finding a device to use for employees to carry around. The other is finding a device with a supported API (read: "free API") or other programming options. I would like this to be manufacturer-independent.
I would love to do cross-platform development - iOS, Android, PC, web, etc.
Does anyone have experience with something like this, and what recommendations can you offer on where to start? I know this is a little open ended but I'm not sure where to start.
Thanks.
This all does not work (tracking within a building).
GPS Signal is very poor or non existent within a building.
(Next time search here on Stackoverflow. It has been asked some times.)
The only robust and working solution, are BlueTooth beacons.
Such small hardware pieces are mounted within the building.
Such beacons (search for iBeacon) just send out an id.
The phone receives the id, and the approximate distance to it.
You have to administrate and know which id is at which level of the building.
Even when having good reception the GPS signal is not precise enough to determine the floor a person is location.
Some phones have a barometer, like the ipHone, this can track relative heigh changes, and may be used to determine level within a building. (Once calibrated before entering the buulding)
how can I correctly identify if the user is driving or not ? I am trying to make an app where I can find my parked car's location.
The simplest way was to ask user to press a button after parking the car so that my app can remember its location.
But I want my app to be automatic. It should correctly recognize if the user is in vehicle or not without interacting with the user.
I tried out Activity Recognition as well but it does not give me exact/correct result. Even when I am walking it says driving and vice versa. I cannot trust it.
There are several apps in the play store which achieve this. I want to learn this as well.
Would some one take some time and help me out on this. It will be of greate help. Thanks a lot in advance :)
I've never done this before, but here are some things I'd try:
location - mainly, how fast their location is changing. probably not great for slow traffic, but if they are moving 60mph, there's no way they are walking. You could also combine this with map data about known roads, or maybe even use locations of well-known airports to know that someone is more likely flying than driving
use the device's accelerometers to compute it's speed (in conjunction with location info to correct for accumulated error).
have the user connect their device to the car with bluetooth - and then when the connection drops, you know they aren't in their car. Or better yet, figure out if you can just detect they are in the car from strength of the bluetooth signal. Though I'm not sure that's possible.
(maybe) ask your users to use a simple RFID chip in their car, and then use that as an indicator of whether or not the phone is in the car. Of course this has implications on the user experience.
in a different vein, maybe some sensor on the device could pick up vibrations? Just thinking that car rides aren't perfectly smooth, so any vibration sensing + some signal processing (DFT the data, then look for certain low frequencies that correspond to driving - probably low frequency and below audible).
The best? Probably a combination of all of the above. The more signals you can gather, the better. Perhaps you could even collect a bunch of data, and try to use it to train a classifier? Then again, if any one of these signals turns out to be strong enough, you might not need the others. Be sure to test a variety of scenarios, e.g. phone in the cup holder v. in your pocket, city driving & slow traffic v. highway driving / empty streets, etc.
I'd be curious to know if any of these ideas pan out.
Also fwiw, Determining if user is driving using gps appears relevant - though it's a simple speed-based check - if you cruise around a parking lot at 8mph looking for a spot, you'll completely fail at catching where the car is parked if your threshold is 10mph.
If the speed drops from above 40km/h to under 7km/h, and stays low for more than 5 minutes.
I'm working with android sensor data. My application use
SensorManager.getRotationMatrixFromVector(
mRotationMatrix , event.values);
and it has been working well until this morning, when the rotation matrix started to send a lot of noise data (Change N to W in a second).
It's not a problem with my code, because on friday was working and no changes have been done. I have used a compass app from the market, and the compass is giving random data.
I have tested my app on another tablet, and it is working well.
Does someone know why is this happening? A problem with the sensor? Does it need a calibration?
I've worked quite a lot with these electronic compasses on mobile phones and its quite possible that there is nothing wrong with your code or sensor.
Instead it could very well be a problem with your environment. There are magnetic fields interfering with the earth's magnetic fields all the time. From electrical equipment interference to the metal structure holding up a building. At the end of the day a compass is just a magnet. If you stand beside a large lump of metal the compass will be attracted to it and point to it rather than the magnetic north pole.
Try this:
Install GPS status
then turn off all filtering (settings... gps & sensors...sensor filtering... no filtering).
Do the calibration (figure of 8 wavy stuff) and then move the phone around your desk.. near monitors, cables, etc. You'll see it go crazy. The information is completely unreliable. I found in the past that moving the phone a few inches to the right completely changed its reading. The same happens with a real compass. Strictly speaking there is no "problem". The device's compass is assigning itself with the strongest magnetic field. Even the magnetic content of nearby rocks can interfere with the compass.
As a further test I've just placed a real (orienteering) compass over my phone which has a compass app installed. The real compass is now pointing everywhere but magnetic North. The two devices are interfering with each other.
So my advice is.. go somewhere in the open, like a park or field, away from any potential interference and power lines, (if you have one bring a real compass to check that the GPS status app is pointing the right way), and see if your compass works as you'd expect.
Extra: The answer from #resus is also important when calibrating. Rotate the phone a few times in each axis. Looks silly but it does calibrate it properly.
Extra 2: Would it be possible/practical to use the compass bearing of your GPS? It would require that the device be moving (walking speed should be fine) but you would not need to worry about any interference. It should give an accurate reading provided your GPS signal is good.
Extra 3: Another thought just occurred to me.. You could try apply a low pass filter to the sensor. This means that the sudden changes in the sensor reading are filtered out .. have a look at this answer. And if that doesn't do a good job there are lots of algorithms on the web for you to choose from.
If you definitely haven't changed anything in your code, and it still works fine on other devices, it would suggest a problem with that particular device.
While your app is running (i.e. the compass is in use), you should be able to wave it in a figure of 8 in order to automatically recalibrate the compass. You should also make sure you aren't standing next to any large lumps of metal etc. that might interfere with readings.
You can override the onAccuracyChanged() method of SensorEventListener to flash up a message to the user when the compass requires recalibration (probably when accuracy drops to SENSOR_STATUS_ACCURACY_LOW).
In my experience of playing with the compass on android phones, they can be pretty unreliable...
If your application work on another tablet and other compass application do not work on your device, this is probably due to a bad calibration.
As said in the post above, to make the calibration, wave your device in a figure of 8. I just want to add that you should do it for EACH axis. This should fix your problem.
If it is not a calibration error, as some people have already answered, it is possible that the compass had gone through a magnetic field and now it is desmagnetized, so it is not working properly.
Where do you usually keep the tablet? Could it be that it was near big servers or magnets?
You should check the compass just in case, talk to to android's tech support.
Hope it helps.
I think the question was if calibration could be done without sending any data to compass. Because not everybody says that the compass is calibrated as shown in this video: https://support.google.com/maps/answer/6145351?hl=en and obviously you can not do anything else than advise the user to calibrate before using the program or when you get too much changes.
For example going left and right 90 degrees in about 25 ms.
Anyway I think it's good to give some seconds to the app before start taking data, because it gives some unstable values (too high and low in short time without movement) at the app loading moment.
Just let the handler onSensorChanged() coded with a conditional, and start a thread on the onCreate() handler, which will set a boolean to true, after some seconds.
Then you start to capture data on the onSensorChanged() handler.
Also this thread can help to detect the sensor accuracy, and then you can popup: In Android can I programmatically detect that the compass is not yet calibrated?
I know because I am building a robot using the compass of the smartphone, and I'm having this experience. So, if you are making a robot, make sure to give an spaced place between electronics and hardware to the smartphone, but remember that it's on any compass: electromagnetic fields can be altered by metals so heavily.
Nowadays I have the luck of developing a robot with an HMC-5983 and an MPU-6050, which can be calibrated by using its libraries with Arduino.
That code is compatible/portable to other uController but for not also so easy for smartphones, I guess that the offsets needed for calibrating the compass, the gyro and the accelerometer are inside some internals of Android, not available in the SDK.
I answered before thinking that maybe calibration was only for some devices, but realized that must be as I said before.
So, if playing with robots its possible, I mean it's also easy, but when using an smartphone maybe some custom firmware as CyanogenMod would bring the possibility of investigating the way of setting that offsets, but more important to run some program ported from sketch (following its concept only) to get them first ...
So, good luck ! What is also true, is that in both devices (smartphone and my robot) it's need to move them for them to get working well, as I showed you in the video of latest answer, also helpful on robots.
Good luck and a lot of fun with those things, are very powerful.
After doing some asking around and reading, it sounds like you're lucky to get even within 10 meters of accuracy with a GPS on a mobile device (specifically Android).
I've seen a video that shows a home-made device reading out to several decimals. Is this only because of the data format from the chip? (aka, not really precise either?)
Is there any real working way that I can use an Android device to track real static positions within rooms in a building?
Ideally, I'd be able to mark a point in a room and come back to it later with virtually no drift.
The LocationProvider is different from each Android Device you are using. The SDK does not handle the calculation of your exact location but the phone does. But each device can have one or mare LocationProvider, thats why you need to set some Criterias when your picking a LocationProvider.
To get your exact position on the earth the GPS needs 3 points from 3 different satellites. Thats why the GPS works best in the open space. Regarding making a precise calculation on a static persion inside a building, this conflict with the whole scenario of the GPS-System. I'm not saying it's impossible to get a location inside a building but as with any other signals, obstacles that blocks the signal makes is weaker.
If you are inside a barn with thin walls this might work, but inside a 10 storage building your scenario seems quite impossible.
You can though force your phone to get the best LocationProvider and hopefully that will give you the most precise location. And yes, you can get inside 1-2m in precision outside.
I hope this helps a little. Enjoy your project.
I'm making an application that works as a compass..
I'm using the accelerometer and the magnetic field sensors to compute the azimuth angle through, sensor.getOrientation().
I'm searching for something that can improve the magnetic field sensor accuracy, since I'm getting it state of accuracy as UNRELIABLE!
Any one knows anything about this?I'm looking for something that can be either hardcoded or for instance just physically moving the phone until it gets calibrated!
This is not a final answer (I don't know anything for sure), but my understanding from online posts is that waving the phone around in a figure of 8 a few times while the compass is in use is supposed to trigger automatic recalibration. This is what the google maps app suggests, for example. I don't know whether this is dependent on application functionality (something in maps that detects the waving by accelerometer and triggers a recalibration), or something in the android stack, or something specific to per-phone implementations. Try it and see!
Eg discussion: http://androidforums.com/epic-4g-support-troubleshooting/217317-cant-get-compass-calibrate.html
This reference appears to suggest this per-axis / figure-8 rotation process is built-in functionality: http://m.eclipsim.com/gpsstatus/
And here another article that claims this is built-in functionality, and that you don't even need to be running a compass-consuming app for the recalibration to work: http://www.ichimusai.org/2009/06/20/how-to-calibrate-the-htc-magic-compass/
Just a few points
The figure 8 motion works sometimes and not others, I have no idea why, they really need to have some kind of code based way to check if the 8 motion worked (Assuming that the physical motion is actually required)
They also need a way to detect that calibration is required, I looked at the code for the accuracy output (the unreliable constant) and once they send it to you they will not send it again, so for instance if you calibrate but then come within a strong magnetic field it will not resend (not sure why they did that)
One not completely reliable way to detect ongoing issues is that you can also use the magnetic sensor output and do something like field=sqrt(x*x+y*y+z*z) and check that field falls between say 25 and 65 and then ask the user to calibrate if it does not.
The bottom line after testing 18 phones is that I would never depend on a Android based compass with the current crop of phones, accuracy would always be in question.
I have also found even if you are lucky and have a fairly reliable phone you can never be sure that it's calibrated without checking it against a real compass, which kind of defeats the purpose.
NOTE: On a lot of the mis-behaving phones we have found that the sensor writes a calibration file and a tmp file with the same name. If you delete those files and re-boot the phones the calibration file is recreated with zero'd values and the cold start and general calibration problems resolve themselves.
The bad news is that they are stored in /data/misc and require root privileges to get at (thanks Google & Sensor mfg!) so even though I suspect this would solve a lot of problems for a lot of developers it just is not viable from a marketplace app perspective.
I am developing for Android. I'm using Titanium Alloy as development tool with the Titanium Geolocation module.
I have only tested 2 devices [Galaxy Note and S4] against a commercial magnetic compass. Following a calibration process [tilt along the 3 axis] and using 2 different compass apps and the app I'm working on, the Android compass seems accurate enough for basic use ... correlation was good enough for my purpose anyway. I also found the device compass reading to be very sensitive to other magnetic and electrical field interference ... initial mistake I made was to use the compass feature whilst device was in a device protector with a magnetic closure facility [quite common on tabs] ... this interference is particularly strong. I thus need to suggest to users of my app to remove device protectors, keep device free of other electronics and then do standard calibration before initializing the app.
Another option is:
Go To sensors menu: #*0#*
Then if you see a red line in Magnetic Sensor section and a Need for Calibration you should recalibrate your compass.
How;
According those guys;
Turn the Samsung Galaxy Mini S5 around all of its axes until the red
line in the black circle changes color from red to blue. You can also
run through a motion that follows the shape of an 8. It may be that
several attempts are needed to calibrate the compass...