Posted by Geoffrey Boullanger – Senior Software program Engineer, Shandor Dektor – Sensors Algorithms Engineer, Martin Frassl and Benjamin Joseph – Technical Leads and Managers
System orientation, or perspective, is used as an enter sign for a lot of use instances: 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 proper 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 companies that gives high quality and constant system orientation by fusing indicators 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 conduct and excessive efficiency throughout units. We designed the FOP API to be just like the Rotation Vector to make the transition as straightforward as potential for builders.
Specifically, the Fused Orientation Supplier
- Gives a unified implementation throughout units: an API in Google Play companies signifies that there isn’t any implementation variance throughout completely different producers. Algorithm updates may be rolled out shortly and impartial of Android platform updates;
- Immediately incorporates native magnetic declination, if out there;
- Compensates for decrease high quality sensors and OEM implementations (e.g., gyro bias, sensor timing).
In sure instances, the FOP returns values piped via from the AOSP Rotation Vector, tailored to include magnetic declination.
Learn how to use the FOP API
System 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 instances the place the native magnetic declination just isn’t identified (e.g., location just isn’t out there), the orientation will likely 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 identical heading that’s proven in Google Maps, which makes use of the FOP as nicely. We not too long ago added modifications to raised address magnetic disturbances, to enhance the reliability of the cone for Google Maps and FOP shoppers.
The replace charge may be set by requesting a selected replace interval. The FOP doesn’t assure a minimal or most replace charge. For instance, the replace charge may be sooner than requested if one other app has a sooner parallel request, or it may be slower as requested if the system doesn’t help the excessive charge.
For full specification of the API, please seek the advice of the API documentation:
Instance utilization (Kotlin)
bundle ...
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.widespread.flogger.FluentLogger
import java.util.concurrent.Executors
class Instance(context: Context) {
non-public val logger: FluentLogger = FluentLogger.forEnclosingClass()
// Get the FOP API shopper
non-public val fusedOrientationProviderClient: FusedOrientationProviderClient =
LocationServices.getFusedOrientationProviderClient(context)
// Create an FOP listener
non-public val listener: DeviceOrientationListener =
DeviceOrientationListener { orientation: DeviceOrientation ->
// Use the orientation object returned by the FOP, e.g.
logger.atFinest().log("System 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 should have an accelerometer, gyroscope, and magnetometer out there to make use of the fused orientation supplier. It’s preferable that the system vendor implements the excessive constancy sensor portion of the CDD.
Regardless that Android units adhere to the Android CDD, beneficial sensor specs aren’t tight sufficient to totally stop orientation inaccuracies. Examples of this embrace magnetometer interference from inside sources, and delayed, inaccurate or nonuniform sensor sampling. Moreover, the atmosphere across the system often consists of supplies that distort the geomagnetic area, and consumer conduct can fluctuate broadly. To cope with this, the FOP performs plenty of duties with a view to present a strong and correct orientation:
- Synchronize sensors operating on completely 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 this planet;
- Compensate for gyro drift (gyro bias) whereas transferring;
- Produce a practical estimate of the compass heading accuracy.
We now have validated our algorithms on complete check knowledge to supply a top quality outcome on all kinds of units.
Availability and limitations
The Fused Orientation Supplier is offered on all units operating Google Play companies 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 charge is restricted to 200Hz on units operating API stage 31 (Android S) or larger, until the android.permissions.HIGH_SAMPLING_RATE_SENSORS permission was added to your Manifest.xml.
Energy consideration
At all times 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. In the event you have no idea which replace interval to make use of, we advocate beginning with DeviceOrientationRequest::OUTPUT_PERIOD_DEFAULT because it suits most shopper wants.
Foreground conduct
FOP updates are solely out there to apps operating within the foreground.
Copyright 2023 Google LLC. SPDX-License-Identifier: Apache-2.0