I started doing some thinking about creating an Android application that can be used within a corporate building to determine what room you are in. Obviously I'm thinking GPS and network locations wouldn't be accurate enough to accomplish this. (Not to mention the instability of GPS signal inside) I looked briefly into calculating distance via the accelerometer, but it is apparently highly volatile and leaves a large margin for error. I've also considered some sort of triangulation from routers, but you run into issues with walls/microwaves and various other things that could upset the signal strength. Does anyone have any possible ideas or directions to try?
How about bluetooth tags that emit a room id. You could make money merchandising the emitters on a facility size basis and they could provide additional functionality such as:
(1) forming a pico net that ultimately updates the an onsite server with locations of everyone using the app, or
(2) tracking key equipment with a similar bluetooth tag, etc.
You could get something similar to the link below in qty from China, I'm sure:
http://www.engadget.com/2009/03/26/nio-bluetooth-security-tag-keeps-tabs-on-your-belongings/
Perhaps it is not too much help but the papers I have found on this subject are these:
RSSI-Based Indoor Localization and Tracking Using Sigma-Point Kalman Smoothers
Pedestrian Tracking with Shoe-Mounted Inertial Sensors
Enhancing the Performance of Pedometers Using a Single Accelerometer
I have no idea how these methods would perform in real-life applications or how to turn them into a nice Android app.
I am curious what other answers you will get.
Related
I've read through the SDK documentation for both Windows and Android and found some functions for accessing the state of the current GPS connection and Latitude/longitude information.
I am looking to develop an application that uses 3d photogrammatry to monitor a set area in real time and am worried that built-in localization might not update the model accurately enough.
So I am wondering if there is a way to get the lower-level information like connection strength and specific connected satellites. (to compare to GPS information from the ground for better accuracy.) Is this supported? (maybe in specific drones?) Or is my only option to attatch a GPS device to it that I then access seperately?
I also know that DJI offers a drone with GPS-RTK to give this accuracy but I'm looking at alternative approaches because of the big step up in cost.
Any information / suggestions would be of great help! Thanks.
I am sorry to report but there is no access to the raw data from the GPS sensors. The information you found in the SDK documentation is all that is available.
How accurate are you looking for? Generally the accuracy is pretty close, certainly within 1 foot or so and there is specifications for GPS accuracy in specific drone's manuals.
There isn't any more info you can get from the sdk.
I guess you looking for raw meassurements? There is nothing that points to that's possible, even in the dumledore messages.
You better stick with the newer drones, since they seems to use dual freq gps, starting from mini2. Very accurate.
Havn't tried the mavic3 but my guess is that they switched to the same gps-chip as in the mini2.
Ne aware that gps lat/lon you get is actually fused with the imu.
I've been doing a bit of research on a problem we are trying to solve. I think this is the best approach but please add in your opinions
We are trying to calculate reaction times in a real world driving scenario and would like to use a mobile phone as the data collection device. What we are trying to accomplish is how much acceleration and more importantly deceleration a driver exerts when exposed to certain prompts.
I found this paper that has allot of useful information Accelerometer physics
The problem is that we most likely will not have a calibration time to start at zero.. however it is assumed that the driver is starting at 0. We will use GPS positioning to locate the vehicle, tracking the time stamped location data we should calculate the time when the prompt took place then using the time stamped accelerometer data we should be able to calculate their reaction to the prompt.
This is the best way I have found to solve the problem however I'm not sure if the accelerometer data will be rendered useless because of not being able to calibrate it and also the noise seen from vibrations may be too great to use the data... Has anyone tried or used these types of methods before?
Interesting application.
You are missing an important point. You either have to implement the so-called sensor fusion yourself or use the sensor fusion provided on the platform you are using. Both Android and iPhone have one.
The TYPE_LINEAR_ACCELERATION (Android, SensorManager) or userAcceleration (iPhone) should be sufficient for you.
As for the linked PDF, don't try integrating the acceleration, you will get very poor results. Even though that answer is about position, the velocity will already be inaccurate. I would try the GPS instead.
I know it's very old question but since I am recently working on a similar project let me share what we did in our company. We simply used OBD-II dongle to get velocity of car. There are many API's that return information about vehicle.
PID010D returns speed of vehicle. I'm using this PID to calculate distance between points A and B since there is no PID to return Odometer :(
There are few libraries on github that you can find easily by search. This mine. This is not library but after run on your device you can see how it works.
Say an event is being hosted in a large building. There are 20 rooms which are quite difficult to find.
I want to develop an app which points you in the right direction of a specified room or shows on a 3-d map, the location of you, relative to this room. This obviously includes altitude as the building has many floors.
Now, I looked into GPS, which is not very accurate and also depends on the quality of the phone's GPS. I'm not sure if this is really an option for the accuracy I require.
I also looked into Bluetooth beacons, but it is apparently very difficult to add direction to this as well as distance. Plus, this is only accurate at around 20 meters, right?
What other alternatives are out there that I can research myself?
And which options can I definitely eliminate?
I am not looking for a heated debate over the best approach, I know this is against SO rules.
So just a few potential options is all I wasnt, so I can go and research them myself... maybe wifi or something?
GPS you can forget, there is no or very bad receivement indoors.
I would concentrate on blue tooth beacons. Apple provides such iBeacons, too. So this can give you more information what is feasible.
The third possibility is magnetic field analysis, but i dont trust much that solutions. Altough there are demos and even an ios App (Indoor Atlas), this soultion has some drawbacks. Change of magnetic field after change in construction / furniture.
I've been doing a bit of research on a problem we are trying to solve. I think this is the best approach but please add in your opinions
We are trying to calculate reaction times in a real world driving scenario and would like to use a mobile phone as the data collection device. What we are trying to accomplish is how much acceleration and more importantly deceleration a driver exerts when exposed to certain prompts.
I found this paper that has allot of useful information Accelerometer physics
The problem is that we most likely will not have a calibration time to start at zero.. however it is assumed that the driver is starting at 0. We will use GPS positioning to locate the vehicle, tracking the time stamped location data we should calculate the time when the prompt took place then using the time stamped accelerometer data we should be able to calculate their reaction to the prompt.
This is the best way I have found to solve the problem however I'm not sure if the accelerometer data will be rendered useless because of not being able to calibrate it and also the noise seen from vibrations may be too great to use the data... Has anyone tried or used these types of methods before?
Interesting application.
You are missing an important point. You either have to implement the so-called sensor fusion yourself or use the sensor fusion provided on the platform you are using. Both Android and iPhone have one.
The TYPE_LINEAR_ACCELERATION (Android, SensorManager) or userAcceleration (iPhone) should be sufficient for you.
As for the linked PDF, don't try integrating the acceleration, you will get very poor results. Even though that answer is about position, the velocity will already be inaccurate. I would try the GPS instead.
I know it's very old question but since I am recently working on a similar project let me share what we did in our company. We simply used OBD-II dongle to get velocity of car. There are many API's that return information about vehicle.
PID010D returns speed of vehicle. I'm using this PID to calculate distance between points A and B since there is no PID to return Odometer :(
There are few libraries on github that you can find easily by search. This mine. This is not library but after run on your device you can see how it works.
I am developing a project that is intended to use the GPS capabilities of an Android phone and a nearby station to compute positioning to a much more precise degree (cm), using RTK DGPS technology.
So far, I haven't been able to see anyone saying they actually managed to perform a similar task (apart from #GPSmaster, who doesn't explain how), and the APK doesn't seem to offer any information from the GPS chip other than location and NMEA message updates. I need, if possible, pseudo-ranges and carrier phases.
I was wondering if:
It would be possible to look for lower level hooks on my phone using native code, or other lower level snooping;
It would be possible to send RTCM corrections to the GPS chip present on one of these devices;
Any ideas?
Generally speaking DGPS is a technique that improves real position accuracy by canceling out most of the atmospheric effects on the GPS signal. In a typical direct GPS measurement there is about a random error in the ranges computed to the satellites due to atmospheric effects. This is why a GPS receiver that is left collecting data in a fixed location will seem to wander with in an error ellipse. For two receiver stations in the same area the atmospheric effects are almost identical and they will wander in parallel within their similarly sized and oriented error ellipses. If one of the two receivers is at a know location then the differences in their apparent GPS locations can be taken and plotted from the true location of the known station to find the true location of the unknown station.
Back in the day (circa 1992) when we had to accomplish DGPS by "post processing" we used to take the raw NEMA data collected at the two stations match up the times, compute the baseline vector and apply it to the known point to find the unknown point. I think the NEMA data we were using was only recorded to the nearest 10 sec. The math isn't really that hard.
I suspect that NEMA GPS messages [http://developer.android.com/reference/android/location/GpsStatus.NmeaListener.html ] from a tablet at a known point (with a clear sky view) could probably be sent over an internet socket to a smart phone (also with a clear sky view), which could then compute the difference and achieve a sub-meter relative location over a distance of few km, even if the assumed Internet transit times were ignored. This technique would probably still work even if the tablet and smart phone were both applying broadcast DGPS adjustments.
With the andvent of Android 7.1, the raw data from GPS chips will be available to developers. (http://gpsworld.com/google-to-provide-raw-gnss-measurements/)
Others seem to have done something similar to what you wish to accomplish (http://gpsworld.com/innovation-precise-positioning-using-raw-gps-measurements-from-android-smartphones/)
No, it is not practical to get any lower level access to the GPS device by an Android application. This has several reasons:
The application has no other means of accessing the GPS device as through the Java based API. Native code is forbidden to use most devices and usually needs a Java wrapper to tunnel through the sandbox for Android sensor devices. This makes up the main security concept.
If native code would have access to the GPS device on a lower level, it would have to cope with several different manufacturers protocols now not abstracted by the API. Best chances are to get access to custom NMEA codes, which may still have device dependent caveats.
Even if lower level access would be possible, one loses the integrated merging of other location sources like WLAN and cellphone carrier, that are presumably merged in native code below the Java API but above the NMEA protocol.
You can use DGPS corrections in Europe via custom application for SISnet receiving correction signals from EGNOS augmentation satellites(http://egnos-portal.gsa.europa.eu/news/egnos-gets-invite-your-smartphone-11). It does however need a subscription (which isn't really open to public yet) to SISnet to obtain username and password for connection to their servers. There's some of SDK published which you may find useful. Just remember that you are limited to C/A signals only (pseudoranges) and you CANNOT get phase data (L1/L2) from those cheap chips inside smartphones.You'd need a precision GNSS receiver such as Trimble BD910 (http://www.trimble.com/gnss-inertial/bd910.aspx?dtID=overview) to be able to access L1 carrier phase signal for GPS & GLONASS. There are however cheaper chips that support SBAS but none are yet installed natively in phones.
Umm. Your android probably has such a crap GPS antenna that achieving cm accuracy is impossible. Maybe if you average the position for days.. usually DGPS support is not published and not many chipsets support it. Last time I saw DGPS implemented it involved hacking the actual GPS chip firmware to add support. Even getting A-GPS to work on a random chipset is iffy since they might not support a documented way of feeding the assistance data.
It should be related with the hardware implementation , rather than the software implementation.
In the reality, GPS is usually accompanied with Wi-Fi or 3G to assist in searching the current position.
RTCM correction can be sent to your android phone using NTRIP 'provider'. Then you need to apply it to your raw GPS in your android.