Android – GPS V.S. accelerometer to calculate distance

accelerometerandroidgps

I am trying to implement a fitness app that can keep track of the running speed and running distance in Android.

It looks like I can either use GPS or Accelerometer to calculate these information.

Since a runner may put his phone in hand, on the shoulder or in his pocket, my first intuition is to use GPS to get locations and calculate running speed and running distance. But recently someone telled me that I can also use Accelerometer also does that.

My question is: In Android, which approach is better to calculate running speed and running distance, GPS or Accelerometer?

Best Answer

I suspect that pedometers are based on accelerometers because accelerometers are cheaper than GPS to use. in fact I think a lot of pedometers don't even try to measure distance. just acceleration jolts which equal steps. and then if they give you a distance measurement, it's by multiplying detected steps by a guessed or average step size.

GPS (if you are in an area where it works!) will do a very good measurement of distance. Even with a very cheap GPS receiver. All being basically OK, you should expect start and end positions to within 10m, and so for a 1km travel, you have 20m of uncertianty, which is 2% total distance uncertianty. This uncertianty goes down linearly with distance travelled (ie a 2km run will have 1% uncertianty, 4 km run will have 0.5% uncertianty, etc) the issues here will be with your realtime displays (GPS position jumps from satellite switching giving massive speed values, or immediate loss of signal giving a loss of all immediately displayable data)

I think that with a good accelerometer, starting from stopped you can continually integrate the signal to get speed, and continually integrate that result to get distance... I am just unsure what kind of accelerometer quality you get in any given phone? you may need to filter for noise or even garbage data.. And you also need to consider what accuracy it has. 20% accuracy in your sensor would make for a very bad distance tracker. So you might have to work with step counting and step size guesstimates.

perhaps a combination of both could work?

I'd be tempted to use the accelerometer data (either integrating or step counting depending on what will always work) to track speed and distance in short timeframe, then with much longer timeframe, generalised GPS data could be used to correct or scale that data from the accelerometer. Especially if you filtered/blocked GPS data based on uncertianty measurement at any given time.

Related Solutions

Android – How to get the current GPS location programmatically in Android

I have created a small application with step by step description to get current location's GPS coordinates.

Complete example source code is in Get Current Location coordinates , City name - in Android.

See how it works:

All we need to do is add this permission in the manifest file:

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />

And create a LocationManager instance like this:

LocationManager locationManager = (LocationManager)
getSystemService(Context.LOCATION_SERVICE);

Check if GPS is enabled or not.

And then implement LocationListener and get coordinates:

LocationListener locationListener = new MyLocationListener();
locationManager.requestLocationUpdates(
LocationManager.GPS_PROVIDER, 5000, 10, locationListener);

Here is the sample code to do so

/*---------- Listener class to get coordinates ------------- */
private class MyLocationListener implements LocationListener {

    @Override
    public void onLocationChanged(Location loc) {
        editLocation.setText("");
        pb.setVisibility(View.INVISIBLE);
        Toast.makeText(
                getBaseContext(),
                "Location changed: Lat: " + loc.getLatitude() + " Lng: "
                    + loc.getLongitude(), Toast.LENGTH_SHORT).show();
        String longitude = "Longitude: " + loc.getLongitude();
        Log.v(TAG, longitude);
        String latitude = "Latitude: " + loc.getLatitude();
        Log.v(TAG, latitude);

        /*------- To get city name from coordinates -------- */
        String cityName = null;
        Geocoder gcd = new Geocoder(getBaseContext(), Locale.getDefault());
        List<Address> addresses;
        try {
            addresses = gcd.getFromLocation(loc.getLatitude(),
                    loc.getLongitude(), 1);
            if (addresses.size() > 0) {
                System.out.println(addresses.get(0).getLocality());
                cityName = addresses.get(0).getLocality();
            }
        }
        catch (IOException e) {
            e.printStackTrace();
        }
        String s = longitude + "\n" + latitude + "\n\nMy Current City is: "
            + cityName;
        editLocation.setText(s);
    }

    @Override
    public void onProviderDisabled(String provider) {}

    @Override
    public void onProviderEnabled(String provider) {}

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {}
}

Android – How to use Accelerometer to measure distance for Android Application Development

You get position by integrating the linear acceleration twice but the error is horrible. It is useless in practice.

Here is an explanation why (Google Tech Talk) at 23:20. I highly recommend this video.

Best Answer

Related Solutions

Android – How to get the current GPS location programmatically in Android

Android – How to use Accelerometer to measure distance for Android Application Development

Related Topic