/motion

name: motion
description: Stream accelerometer, gyroscope, magnetometer, and orientation samples from connected wearables on Android

Motion (Android)

Motion is an experimental capability for streaming inertial sensor samples. Enable it for the app in Wearables Developer Center. It has no runtime `Permission` value.

Attach, collect, and start

Call `addMotion` only after `DeviceSessionState.STARTED`. The returned capability starts in `STOPPED`; launch collectors before calling `start()`.

session.addMotion(
    MotionConfiguration(samplingRate = MotionSamplingRate.HZ_30),
).fold(
    onSuccess = { motion ->
        motionSampleJob = lifecycleScope.launch {
            motion.samples.collect { sample -> render(sample) }
        }
        motion.start()
    },
    onFailure = { error, _ -> showError(error.description) },
)

Retain the sample job while streaming. Collect `state` for lifecycle updates and `errors` for sensor, connection, and closure failures.

Sampling rates are 5, 10, 15, 24, 30, and 60 Hz; 10 Hz is the default.

Read samples defensively

`timestampNs` uses the device monotonic clock. Accelerometer values are m/s², gyroscope values are rad/s, and magnetometer values are µT. Each sensor value and orientation can be `null`; `source` identifies glasses, Neural Band, or an unknown source.

Motion normally transitions `STOPPED -> STARTING -> STARTED`. When its parent session pauses, it reports `MotionState.PAUSED` and automatically restarts when the session resumes.

Stop and remove

`motion.stop()` is reusable. Cancel the sample job before calling `session.removeMotion()` and handle its `DatResult`; removal is terminal.

Test with MockDeviceKit

Replay an in-memory recording with `glasses.services.motion.setMotionFeed(samples, loop = true)` or provide a CSV file URI. App logic should observe the SDK Motion state rather than `isStreaming`, which is a test assertion helper.

Availability

Motion is experimental. Apps can use it for development and beta testing, but cannot publish it to production release channels yet.