I'm working on a robot which need to know its exact position (with an error of +/- 5cm) in relation to a given point of coordinates (0, 0). So my question is :
Is it possible to get this kind of precision using differential GPS ?
The idea would be to place a GPS at the position (0, 0) and a GPS on the robot to compute the difference of coordinates of the 2 GPS and get the relative position of the robot.
Thanks for your answers
It is possible with DGPS, but bot in an mobile phone.
Precision Farming use GPS with cm accuracy.
With a consumer GPS if you would be able to read out the Satellite RAW data, you could do a GPS Post processing, that way you could reach <1m accuracy.
for cm accuracy you need 2 Phase Gps receiver (conusmer ois 1 -phase),
and additional RTK, Then you have cm accuracy.
Read more by searching for topic RTK, Rinex, GPS Post processing.
(But it is not possible for current mobile phones, using GPS)
And robotoers often want to work indoors, where GPS doesn not work, too.
No, GPS is way too inaccurate for that. Best guess would be that you can use the accelerometer to calculate a relative distance on movement.
Might be placing 3 wifi routers in the field and compute by using their relatively signal strength would give a better appoximation on the robot's current location?
Related
There are any documentation for this? I've checked many formulas and algorithms but didn't find an explicit definition how they get the speed provided in Geolocation object.
The GPS chipset provides the current velocity to the system along with the current location.
The chipset may compute the velocity by comparing location over time and correcting for the curvature of the Earth at the current location, or from the Doppler shift of the received satellite signals.
Whichever method is used, the operating system doesn’t need to do any processing to get the speed. The velocity data is provided along with location and altitude data directly from the GPS chip (actually chips in many newer devices support both GPS and GLONASS, but which system is used is not visible to the user).
Physics.org has a simple explanation of how GPS works
Wherever you are on the planet, at least four GPS satellites are ‘visible’ at any time. Each one transmits information about its position and the current time at regular intervals. These signals, travelling at the speed of light, are intercepted by your GPS receiver, which calculates how far away each satellite is based on how long it took for the messages to arrive.
Once it has information on how far away at least three satellites are, your GPS receiver can pinpoint your location using a process called trilateration.
But you can search for more detailed explanations of the mathematics and physics involved.
It basically scans your location (i.e. your latitude and longitude) and compares with the last check. Using euclidian distance, it can get the distance in the period of time. With the time (for example, if it scans your location every 2 seconds), it can easily estimate your speed by doing Speed = Distance/2.
I'm trying to do a Indoor Positioning Systems (IPS). so GPS will not the best way to do this. my question is, s it possible to get location using Earth’s magnetic field (Sensor.TYPE_MAGNETIC_FIELD) ? why I come up like because of this article
Hope you guys will help me out... or if you guys have a good idea better than this please comment.... have a nice day....
GPS will give you coordinates,
Magnetic field will give BEARING.... It will not give the coordinate information.
The example of turtles that you gave are not concerned with their coordinates.... They use the magnetic field to know which direction they are heading in
If GPS is very slow/innacurate for you, Try using FusedLocation API,
It will use GPS, Network (signal triangulation), proximity and the magnetic sensors to provide an accurate Location and Bearing faster than just using a GPS...
NOTE: For it to work fast, the Data/wifi has to be on... else it will use just GPS if you requested a FINE Location and it will again be very slow indoors
Options for accuracy/power in fused provider
https://developers.google.com/android/reference/com/google/android/gms/location/LocationRequest
FusedLocationProvider details:
https://developers.google.com/android/reference/com/google/android/gms/location/FusedLocationProviderApi
Id like to narrow down the location of a phone to the cm or less than a foot (nothing creepy I promise :). Say there was a room full of people I would like 1 user to be able to look though an augmented reality view on their phone to find another user.
Only problem is the location data, I know gps is probably out since I think its only accurate to 10-15 meters? Could you do something with the wifi points, ie have a couple and measure ping time between them to work out location? Or does this technology already exist? Thanks C
Android provides basically two location provider :
GPS
Network
GPS is the most accurate source which you don't want to use and it's slow.
Network location provider is false but less accurate than gps.
So the only hope is GPS.
I am new to android. I was wondering if there was way to locate Cell towers (ie. get gps coordinates) ? I have written the code which gives me LAC, CID and RSSI of neighboring Cell towers.
Yes, it would be possible, simply log the current location with the RSSI of the basestation and when enough data is gathered try and calculate the position of the Cell tower. I would also suggest taking a look at this answer which asks the same question from a non-programming perspective.
A cheap way of doing the estimation would be taking last 3 measuring points (you probably want to make sure that they are x meters away from each other for better accuracy) and then using triangulation to estimate the position of the cell power. When enough measurements have been done, but calculating the average you would probably get a fair estimate of the location of the base station.
How would I verify/ track device location within a 5' accuracy? I've heard of people using cell towers/ gps combinations.
As far as I know, the only way to get a 5 feet accuracy figure is to use GPS, then it still isn't always that accurate depending on how good a fix of the satellites (clear view to the sky) you have.
Cell tower / Wifi triangulation methods only serve to speed up positioning and will seldom (if ever) be more accurate than satellite positioning methods.
GPS is the way to go. Cell towers won't cut it. In Android (and I believe iOS) the system will provide you with an accuracy reading in addition to the actual location. You could use this value to determine whether the value you've received should be uploaded to your server. Keep in mind using the GPS is very battery intensive and there's no guarantee of how good the accuracy will be. Depending on conditions you may not be able to achieve 5' precision.
As #CommonsWare points out, 5' is really unrealistic anyway although you can get close.
As CommonsWare says you will not get much better that 10 metters accuracy in a consummer-grade device. Even in open sky, the atmosphere characteristcs change minute by minute and thats enough to change the GPS readings.
However, it's teoreticaly possible to increase accuracy if you could get all of the following:
1-There are some stationary GPS receiver stations with fixed known locations which measure the current GPS signals deviation. You would need to have one of those close to you and have access to the data in real time.
2-You would need to have low level access to your phone GPS receiver to read the unprocessed data received from sattelites. This would be different from device to device, and as far as I know, no supplier is providing this access.
3-Finnaly, you would need to do all the calculations required to determine your location applying the deviations got from point 1 above.
good luck.
The only way you can get this type of accuracy is with WAAS. As far as I know, there are no Android handsets that can receive WAAS corrections. If this is for a specific controlled situation, you could use a bluetooth gps receiver with WAAS, and only in WAAS supported locations. However, if this was for a wider deployment, then I think you are out of luck.