Posted by Geoffrey Boullanger – Senior Software program Engineer, Shandor Dektor – Sensors Algorithms Engineer, Martin Frassl and Benjamin Joseph – Technical Leads and Managers
Machine orientation, or perspective, is used as an enter sign for a lot of use circumstances: digital or augmented actuality, gesture detection, or compass and navigation – any time the app wants the orientation of a tool in relation to its environment. We’ve heard from builders that orientation is difficult to get proper, with frequent consumer complaints when orientation is wrong. A maps app ought to present the right route to stroll in direction of when a consumer is navigating to an thrilling restaurant in a international metropolis!
The Fused Orientation Supplier (FOP) is a brand new API in Google Play providers that gives high quality and constant system orientation by fusing alerts from accelerometer, gyroscope and magnetometer.
Though at the moment the Android Rotation Vector already supplies system orientation (and can proceed to take action), the brand new FOP supplies extra constant habits and excessive efficiency throughout gadgets. We designed the FOP API to be just like the Rotation Vector to make the transition as straightforward as doable for builders.
Particularly, the Fused Orientation Supplier
- Supplies a unified implementation throughout gadgets: an API in Google Play providers signifies that there is no such thing as a implementation variance throughout totally different producers. Algorithm updates may be rolled out rapidly and unbiased of Android platform updates;
- Immediately incorporates native magnetic declination, if accessible;
- Compensates for decrease high quality sensors and OEM implementations (e.g., gyro bias, sensor timing).
In sure circumstances, the FOP returns values piped by way of from the AOSP Rotation Vector, tailored to include magnetic declination.
How you can use the FOP API
Machine orientation updates may be requested by creating and sending a DeviceOrientationRequest object, which defines some specifics of the request just like the replace interval.
The FOP then outputs a stream of the system’s orientation estimates as quaternions. The orientation is referenced to geographic north. In circumstances the place the native magnetic declination isn’t identified (e.g., location isn’t accessible), the orientation can be relative to magnetic north.
As well as, the FOP supplies the system’s heading and accuracy, that are derived from the orientation estimate. This is similar heading that’s proven in Google Maps, which makes use of the FOP as nicely. We not too long ago added modifications to higher deal with magnetic disturbances, to enhance the reliability of the cone for Google Maps and FOP purchasers.
The replace fee may be set by requesting a particular replace interval. The FOP doesn’t assure a minimal or most replace fee. For instance, the replace fee may be quicker than requested if one other app has a quicker parallel request, or it may be slower as requested if the system doesn’t help the excessive fee.
For full specification of the API, please seek the advice of the API documentation:
Instance utilization (Kotlin)
package deal ...
import android.content material.Context
import com.google.android.gms.location.DeviceOrientation
import com.google.android.gms.location.DeviceOrientationListener
import com.google.android.gms.location.DeviceOrientationRequest
import com.google.android.gms.location.FusedOrientationProviderClient
import com.google.android.gms.location.LocationServices
import com.google.frequent.flogger.FluentLogger
import java.util.concurrent.Executors
class Instance(context: Context) {
personal val logger: FluentLogger = FluentLogger.forEnclosingClass()
// Get the FOP API shopper
personal val fusedOrientationProviderClient: FusedOrientationProviderClient =
LocationServices.getFusedOrientationProviderClient(context)
// Create an FOP listener
personal val listener: DeviceOrientationListener =
DeviceOrientationListener { orientation: DeviceOrientation ->
// Use the orientation object returned by the FOP, e.g.
logger.atFinest().log("Machine Orientation: %s deg", orientation.headingDegrees)
}
enjoyable begin() {
// Create an FOP request
val request =
DeviceOrientationRequest.Builder(DeviceOrientationRequest.OUTPUT_PERIOD_DEFAULT).construct()
// Create (or re-use) an Executor or Looper, e.g.
val executor = Executors.newSingleThreadExecutor()
// Register the request and listener
fusedOrientationProviderClient
.requestOrientationUpdates(request, executor, listener)
.addOnSuccessListener { logger.atInfo().log("FOP: Registration Success") }
.addOnFailureListener { e: Exception? ->
logger.atSevere().withCause(e).log("FOP: Registration Failure")
}
}
enjoyable cease() {
// Unregister the listener
fusedOrientationProviderClient.removeOrientationUpdates(listener)
}
}
Technical background
The Android ecosystem has all kinds of system implementations for sensors. Gadgets ought to meet the standards within the Android compatibility definition doc (CDD) and will need to have an accelerometer, gyroscope, and magnetometer accessible to make use of the fused orientation supplier. It’s preferable that the system vendor implements the excessive constancy sensor portion of the CDD.
Despite the fact that Android gadgets adhere to the Android CDD, beneficial sensor specs are usually not tight sufficient to totally stop orientation inaccuracies. Examples of this embrace magnetometer interference from inner sources, and delayed, inaccurate or nonuniform sensor sampling. Moreover, the surroundings across the system normally consists of supplies that distort the geomagnetic subject, and consumer habits can differ broadly. To cope with this, the FOP performs plenty of duties to be able to present a strong and correct orientation:
- Synchronize sensors working on totally different clocks and delays;
- Compensate for the arduous iron offset (magnetometer bias);
- Fuse accelerometer, gyroscope, and magnetometer measurements to find out the orientation of the system on the planet;
- Compensate for gyro drift (gyro bias) whereas transferring;
- Produce a sensible estimate of the compass heading accuracy.
Now we have validated our algorithms on complete check information to offer a top quality consequence on all kinds of gadgets.
Availability and limitations
The Fused Orientation Supplier is out there on all gadgets working Google Play providers on Android 5 (Lollipop) and above. Builders want so as to add the dependency play-services-location:21.2.0 (or above) to entry the brand new API.
Permissions
No permissions are required to make use of the FOP API. The output fee is restricted to 200Hz on gadgets working API stage 31 (Android S) or greater, except the android.permissions.HIGH_SAMPLING_RATE_SENSORS permission was added to your Manifest.xml.
Energy consideration
All the time request the longest replace interval (lowest frequency) that’s ample on your use case. Whereas extra frequent FOP updates may be required for prime precision duties (for instance Augmented Actuality), it comes with an influence value. If you happen to have no idea which replace interval to make use of, we suggest beginning with DeviceOrientationRequest::OUTPUT_PERIOD_DEFAULT because it suits most shopper wants.
Foreground habits
FOP updates are solely accessible to apps working within the foreground.
Copyright 2023 Google LLC. SPDX-License-Identifier: Apache-2.0
