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 person complaints when orientation is wrong. A maps app ought to present the right course to stroll in the direction of when a person is navigating to an thrilling restaurant in a overseas 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 offers system orientation (and can proceed to take action), the brand new FOP offers extra constant conduct and excessive efficiency throughout units. We designed the FOP API to be much like the Rotation Vector to make the transition as simple as attainable for builders.
Particularly, the Fused Orientation Supplier
- Offers a unified implementation throughout units: an API in Google Play providers implies that there isn’t a implementation variance throughout completely different producers. Algorithm updates could be rolled out rapidly and unbiased of Android platform updates;
- Immediately incorporates native magnetic declination, if obtainable;
- Compensates for decrease high quality sensors and OEM implementations (e.g., gyro bias, sensor timing).
In sure circumstances, the FOP returns values piped by means of from the AOSP Rotation Vector, tailored to include magnetic declination.
How one can use the FOP API
Machine orientation updates could 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 will not be recognized (e.g., location will not be obtainable), the orientation can be relative to magnetic north.
As well as, the FOP offers 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 effectively. We not too long ago added adjustments to higher deal with magnetic disturbances, to enhance the reliability of the cone for Google Maps and FOP purchasers.
The replace fee could be set by requesting a particular replace interval. The FOP doesn’t assure a minimal or most replace fee. For instance, the replace fee could 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 assist 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 consumer
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. Units ought to meet the factors within the Android compatibility definition doc (CDD) and will need to have an accelerometer, gyroscope, and magnetometer obtainable 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, advisable sensor specs aren’t tight sufficient to totally forestall orientation inaccuracies. Examples of this embrace magnetometer interference from inner sources, and delayed, inaccurate or nonuniform sensor sampling. Moreover, the setting across the system often contains supplies that distort the geomagnetic subject, and person conduct can range broadly. To take care of this, the FOP performs various duties so as to present a sturdy and correct orientation:
- Synchronize sensors working 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 the earth;
- Compensate for gyro drift (gyro bias) whereas transferring;
- Produce a practical estimate of the compass heading accuracy.
We have now validated our algorithms on complete take a look at knowledge to offer a top quality consequence on all kinds of units.
Availability and limitations
The Fused Orientation Supplier is accessible on all units 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 proscribed to 200Hz on units working API degree 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 adequate on your use case. Whereas extra frequent FOP updates could be required for prime precision duties (for instance Augmented Actuality), it comes with an influence price. For those who have no idea which replace interval to make use of, we advocate beginning with DeviceOrientationRequest::OUTPUT_PERIOD_DEFAULT because it matches most consumer wants.
Foreground conduct
FOP updates are solely obtainable to apps working within the foreground.
Copyright 2023 Google LLC. SPDX-License-Identifier: Apache-2.0