/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.server;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Handler;
import android.os.Message;
import android.os.PowerManager;
import android.os.SystemClock;
import android.util.Slog;
import java.lang.Float;
/**
* Determines if the device has been set upon a stationary object.
*/
public class AnyMotionDetector {
interface DeviceIdleCallback {
public void onAnyMotionResult(int result);
}
private static final String TAG = "AnyMotionDetector";
private static final boolean DEBUG = false;
/** Stationary status is unknown due to insufficient orientation measurements. */
public static final int RESULT_UNKNOWN = -1;
/** Device is stationary, e.g. still on a table. */
public static final int RESULT_STATIONARY = 0;
/** Device has been moved. */
public static final int RESULT_MOVED = 1;
/** Orientation measurements are being performed or are planned. */
private static final int STATE_INACTIVE = 0;
/** No orientation measurements are being performed or are planned. */
private static final int STATE_ACTIVE = 1;
/** Current measurement state. */
private int mState;
/** Threshold energy above which the device is considered moving. */
private final float THRESHOLD_ENERGY = 5f;
/** The duration of the accelerometer orientation measurement. */
private static final long ORIENTATION_MEASUREMENT_DURATION_MILLIS = 2500;
/** The maximum duration we will collect accelerometer data. */
private static final long ACCELEROMETER_DATA_TIMEOUT_MILLIS = 3000;
/** The interval between accelerometer orientation measurements. */
private static final long ORIENTATION_MEASUREMENT_INTERVAL_MILLIS = 5000;
/** The maximum duration we will hold a wakelock to determine stationary status. */
private static final long WAKELOCK_TIMEOUT_MILLIS = 30000;
/**
* The duration in milliseconds after which an orientation measurement is considered
* too stale to be used.
*/
private static final int STALE_MEASUREMENT_TIMEOUT_MILLIS = 2 * 60 * 1000;
/** The accelerometer sampling interval. */
private static final int SAMPLING_INTERVAL_MILLIS = 40;
private final Handler mHandler;
private final Object mLock = new Object();
private Sensor mAccelSensor;
private SensorManager mSensorManager;
private PowerManager.WakeLock mWakeLock;
/** Threshold angle in degrees beyond which the device is considered moving. */
private final float mThresholdAngle;
/** The minimum number of samples required to detect AnyMotion. */
private int mNumSufficientSamples;
/** True if an orientation measurement is in progress. */
private boolean mMeasurementInProgress;
/** The most recent gravity vector. */
private Vector3 mCurrentGravityVector = null;
/** The second most recent gravity vector. */
private Vector3 mPreviousGravityVector = null;
/** Running sum of squared errors. */
private RunningSignalStats mRunningStats;
private DeviceIdleCallback mCallback = null;
public AnyMotionDetector(PowerManager pm, Handler handler, SensorManager sm,
DeviceIdleCallback callback, float thresholdAngle) {
if (DEBUG) Slog.d(TAG, "AnyMotionDetector instantiated.");
synchronized (mLock) {
mWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, TAG);
mWakeLock.setReferenceCounted(false);
mHandler = handler;
mSensorManager = sm;
mAccelSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
mMeasurementInProgress = false;
mState = STATE_INACTIVE;
mCallback = callback;
mThresholdAngle = thresholdAngle;
mRunningStats = new RunningSignalStats();
mNumSufficientSamples = (int) Math.ceil(
((double)ORIENTATION_MEASUREMENT_DURATION_MILLIS / SAMPLING_INTERVAL_MILLIS));
if (DEBUG) Slog.d(TAG, "mNumSufficientSamples = " + mNumSufficientSamples);
}
}
/*
* Acquire accel data until we determine AnyMotion status.
*/
public void checkForAnyMotion() {
if (DEBUG) {
Slog.d(TAG, "checkForAnyMotion(). mState = " + mState);
}
if (mState != STATE_ACTIVE) {
synchronized (mLock) {
mState = STATE_ACTIVE;
if (DEBUG) {
Slog.d(TAG, "Moved from STATE_INACTIVE to STATE_ACTIVE.");
}
mCurrentGravityVector = null;
mPreviousGravityVector = null;
mWakeLock.acquire();
Message wakelockTimeoutMsg = Message.obtain(mHandler, mWakelockTimeout);
mHandler.sendMessageDelayed(wakelockTimeoutMsg, WAKELOCK_TIMEOUT_MILLIS);
startOrientationMeasurementLocked();
}
}
}
public void stop() {
synchronized (mLock) {
if (mState == STATE_ACTIVE) {
mState = STATE_INACTIVE;
if (DEBUG) Slog.d(TAG, "Moved from STATE_ACTIVE to STATE_INACTIVE.");
}
if (mMeasurementInProgress) {
mMeasurementInProgress = false;
mSensorManager.unregisterListener(mListener);
}
mHandler.removeCallbacks(mMeasurementTimeout);
mHandler.removeCallbacks(mSensorRestart);
mCurrentGravityVector = null;
mPreviousGravityVector = null;
if (mWakeLock.isHeld()) {
mWakeLock.release();
mHandler.removeCallbacks(mWakelockTimeout);
}
}
}
private void startOrientationMeasurementLocked() {
if (DEBUG) Slog.d(TAG, "startOrientationMeasurementLocked: mMeasurementInProgress=" +
mMeasurementInProgress + ", (mAccelSensor != null)=" + (mAccelSensor != null));
if (!mMeasurementInProgress && mAccelSensor != null) {
if (mSensorManager.registerListener(mListener, mAccelSensor,
SAMPLING_INTERVAL_MILLIS * 1000)) {
mMeasurementInProgress = true;
mRunningStats.reset();
}
Message measurementTimeoutMsg = Message.obtain(mHandler, mMeasurementTimeout);
mHandler.sendMessageDelayed(measurementTimeoutMsg, ACCELEROMETER_DATA_TIMEOUT_MILLIS);
}
}
private int stopOrientationMeasurementLocked() {
if (DEBUG) Slog.d(TAG, "stopOrientationMeasurement. mMeasurementInProgress=" +
mMeasurementInProgress);
int status = RESULT_UNKNOWN;
if (mMeasurementInProgress) {
mSensorManager.unregisterListener(mListener);
mHandler.removeCallbacks(mMeasurementTimeout);
mMeasurementInProgress = false;
mPreviousGravityVector = mCurrentGravityVector;
mCurrentGravityVector = mRunningStats.getRunningAverage();
if (mRunningStats.getSampleCount() == 0) {
Slog.w(TAG, "No accelerometer data acquired for orientation measurement.");
}
if (DEBUG) {
Slog.d(TAG, "mRunningStats = " + mRunningStats.toString());
String currentGravityVectorString = (mCurrentGravityVector == null) ?
"null" : mCurrentGravityVector.toString();
String previousGravityVectorString = (mPreviousGravityVector == null) ?
"null" : mPreviousGravityVector.toString();
Slog.d(TAG, "mCurrentGravityVector = " + currentGravityVectorString);
Slog.d(TAG, "mPreviousGravityVector = " + previousGravityVectorString);
}
mRunningStats.reset();
status = getStationaryStatus();
if (DEBUG) Slog.d(TAG, "getStationaryStatus() returned " + status);
if (status != RESULT_UNKNOWN) {
if (mWakeLock.isHeld()) {
mWakeLock.release();
mHandler.removeCallbacks(mWakelockTimeout);
}
if (DEBUG) {
Slog.d(TAG, "Moved from STATE_ACTIVE to STATE_INACTIVE. status = " + status);
}
mState = STATE_INACTIVE;
} else {
/*
* Unknown due to insufficient measurements. Schedule another orientation
* measurement.
*/
if (DEBUG) Slog.d(TAG, "stopOrientationMeasurementLocked(): another measurement" +
" scheduled in " + ORIENTATION_MEASUREMENT_INTERVAL_MILLIS +
" milliseconds.");
Message msg = Message.obtain(mHandler, mSensorRestart);
mHandler.sendMessageDelayed(msg, ORIENTATION_MEASUREMENT_INTERVAL_MILLIS);
}
}
return status;
}
/*
* Updates mStatus to the current AnyMotion status.
*/
public int getStationaryStatus() {
if ((mPreviousGravityVector == null) || (mCurrentGravityVector == null)) {
return RESULT_UNKNOWN;
}
Vector3 previousGravityVectorNormalized = mPreviousGravityVector.normalized();
Vector3 currentGravityVectorNormalized = mCurrentGravityVector.normalized();
float angle = previousGravityVectorNormalized.angleBetween(currentGravityVectorNormalized);
if (DEBUG) Slog.d(TAG, "getStationaryStatus: angle = " + angle
+ " energy = " + mRunningStats.getEnergy());
if ((angle < mThresholdAngle) && (mRunningStats.getEnergy() < THRESHOLD_ENERGY)) {
return RESULT_STATIONARY;
} else if (Float.isNaN(angle)) {
/**
* Floating point rounding errors have caused the angle calcuation's dot product to
* exceed 1.0. In such case, we report RESULT_MOVED to prevent devices from rapidly
* retrying this measurement.
*/
return RESULT_MOVED;
}
long diffTime = mCurrentGravityVector.timeMillisSinceBoot -
mPreviousGravityVector.timeMillisSinceBoot;
if (diffTime > STALE_MEASUREMENT_TIMEOUT_MILLIS) {
if (DEBUG) Slog.d(TAG, "getStationaryStatus: mPreviousGravityVector is too stale at " +
diffTime + " ms ago. Returning RESULT_UNKNOWN.");
return RESULT_UNKNOWN;
}
return RESULT_MOVED;
}
private final SensorEventListener mListener = new SensorEventListener() {
@Override
public void onSensorChanged(SensorEvent event) {
int status = RESULT_UNKNOWN;
synchronized (mLock) {
Vector3 accelDatum = new Vector3(SystemClock.elapsedRealtime(), event.values[0],
event.values[1], event.values[2]);
mRunningStats.accumulate(accelDatum);
// If we have enough samples, stop accelerometer data acquisition.
if (mRunningStats.getSampleCount() >= mNumSufficientSamples) {
status = stopOrientationMeasurementLocked();
}
}
if (status != RESULT_UNKNOWN) {
mHandler.removeCallbacks(mWakelockTimeout);
mCallback.onAnyMotionResult(status);
}
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
};
private final Runnable mSensorRestart = new Runnable() {
@Override
public void run() {
synchronized (mLock) {
startOrientationMeasurementLocked();
}
}
};
private final Runnable mMeasurementTimeout = new Runnable() {
@Override
public void run() {
int status = RESULT_UNKNOWN;
synchronized (mLock) {
if (DEBUG) Slog.i(TAG, "mMeasurementTimeout. Failed to collect sufficient accel " +
"data within " + ACCELEROMETER_DATA_TIMEOUT_MILLIS + " ms. Stopping " +
"orientation measurement.");
status = stopOrientationMeasurementLocked();
}
if (status != RESULT_UNKNOWN) {
mHandler.removeCallbacks(mWakelockTimeout);
mCallback.onAnyMotionResult(status);
}
}
};
private final Runnable mWakelockTimeout = new Runnable() {
@Override
public void run() {
synchronized (mLock) {
stop();
}
}
};
/**
* A timestamped three dimensional vector and some vector operations.
*/
public static final class Vector3 {
public long timeMillisSinceBoot;
public float x;
public float y;
public float z;
public Vector3(long timeMillisSinceBoot, float x, float y, float z) {
this.timeMillisSinceBoot = timeMillisSinceBoot;
this.x = x;
this.y = y;
this.z = z;
}
public float norm() {
return (float) Math.sqrt(dotProduct(this));
}
public Vector3 normalized() {
float mag = norm();
return new Vector3(timeMillisSinceBoot, x / mag, y / mag, z / mag);
}
/**
* Returns the angle between this 3D vector and another given 3D vector.
* Assumes both have already been normalized.
*
* @param other The other Vector3 vector.
* @return angle between this vector and the other given one.
*/
public float angleBetween(Vector3 other) {
Vector3 crossVector = cross(other);
float degrees = Math.abs((float)Math.toDegrees(
Math.atan2(crossVector.norm(), dotProduct(other))));
Slog.d(TAG, "angleBetween: this = " + this.toString() +
", other = " + other.toString() + ", degrees = " + degrees);
return degrees;
}
public Vector3 cross(Vector3 v) {
return new Vector3(
v.timeMillisSinceBoot,
y * v.z - z * v.y,
z * v.x - x * v.z,
x * v.y - y * v.x);
}
@Override
public String toString() {
String msg = "";
msg += "timeMillisSinceBoot=" + timeMillisSinceBoot;
msg += " | x=" + x;
msg += ", y=" + y;
msg += ", z=" + z;
return msg;
}
public float dotProduct(Vector3 v) {
return x * v.x + y * v.y + z * v.z;
}
public Vector3 times(float val) {
return new Vector3(timeMillisSinceBoot, x * val, y * val, z * val);
}
public Vector3 plus(Vector3 v) {
return new Vector3(v.timeMillisSinceBoot, x + v.x, y + v.y, z + v.z);
}
public Vector3 minus(Vector3 v) {
return new Vector3(v.timeMillisSinceBoot, x - v.x, y - v.y, z - v.z);
}
}
/**
* Maintains running statistics on the signal revelant to AnyMotion detection, including:
* <ul>
* <li>running average.
* <li>running sum-of-squared-errors as the energy of the signal derivative.
* <ul>
*/
private static class RunningSignalStats {
Vector3 previousVector;
Vector3 currentVector;
Vector3 runningSum;
float energy;
int sampleCount;
public RunningSignalStats() {
reset();
}
public void reset() {
previousVector = null;
currentVector = null;
runningSum = new Vector3(0, 0, 0, 0);
energy = 0;
sampleCount = 0;
}
/**
* Apply a 3D vector v as the next element in the running SSE.
*/
public void accumulate(Vector3 v) {
if (v == null) {
if (DEBUG) Slog.i(TAG, "Cannot accumulate a null vector.");
return;
}
sampleCount++;
runningSum = runningSum.plus(v);
previousVector = currentVector;
currentVector = v;
if (previousVector != null) {
Vector3 dv = currentVector.minus(previousVector);
float incrementalEnergy = dv.x * dv.x + dv.y * dv.y + dv.z * dv.z;
energy += incrementalEnergy;
if (DEBUG) Slog.i(TAG, "Accumulated vector " + currentVector.toString() +
", runningSum = " + runningSum.toString() +
", incrementalEnergy = " + incrementalEnergy +
", energy = " + energy);
}
}
public Vector3 getRunningAverage() {
if (sampleCount > 0) {
return runningSum.times((float)(1.0f / sampleCount));
}
return null;
}
public float getEnergy() {
return energy;
}
public int getSampleCount() {
return sampleCount;
}
@Override
public String toString() {
String msg = "";
String currentVectorString = (currentVector == null) ?
"null" : currentVector.toString();
String previousVectorString = (previousVector == null) ?
"null" : previousVector.toString();
msg += "previousVector = " + previousVectorString;
msg += ", currentVector = " + currentVectorString;
msg += ", sampleCount = " + sampleCount;
msg += ", energy = " + energy;
return msg;
}
}
}