服务中的SensorEventListener似乎导致了frameskips

时间:2014-03-16 07:12:41

标签: android service android-asynctask frames sensormanager

对不起,如果我的问题看起来太具体了,不过就这样了。

我尝试做的事情:编写一个应用程序来检测摔倒(老人)并发出通知。

问题:应用程序卡在某处,最终根据LogCat跳过帧。它也会卡在一个状态,有时可能与跳帧有关,也可能没有。

目前,我正在处理我检测到坠落的部分,我想在UI中更改ImageView以指示发生了跌落。我已经弄清楚了我是如何检测掉跌倒的,并将其作为状态机实现。

起初,我只使用实现SensorEventListener的服务。这很好,但出乎意料的是,我开始注意跳帧通知。然后我读到Service在主线程上运行,这似乎是当时问题的根源。因此,经过一些搜索,我决定尝试运行一个AsyncTask,从服务中实现SensorEventListener。这根本没有帮助,阻塞了LogCat,进一步造成混乱。该应用程序当然已经构建并运行,但是仍然存在框架问题并且我仍然没有获得理想的结果。我喜欢测试我的检测跌倒的方法是否真的有效,但是我无法确定框架等是怎么回事。

这是我的全部服务代码:

public class DetectionService extends Service{

private static final String TAG = "DetectionService";
private static final float g_2 = 96.2361f;      // gravity squared
private static final float FREEFALL_THRESHOLD_MULTIPLIER = 0.21f;   // when acceleration approx. equal 4.5 m/s/s
private static final float IMPACT_THRESHOLD_MULTIPLIER = 2.1f;      // when acceleration approx. equal 20 m/s/s

private SensorManager mSensorManager = null;
private Sensor accSensor;
private Sensor linAccSensor;
private Sensor gyroSensor;

private Thread reporter;
private Handler handler;
private CountDownTimer debounceTimer;   // used to debounce signal
private CountDownTimer stillnessTimer;  // used for detecting stillness longer than 5 seconds

private boolean fallen = false;
private boolean timeUp = false;
private boolean isStill = false;
private int state = 1;      // 0 = fallen, 1 = detecting free fall, 2 = detecting impact, 3 = waiting 1 second, 4 = detecting stillness



public DetectionService() {

    state = 1;      // initial state, subject is fine
    fallen = false;

    stillnessTimer = new CountDownTimer(5000, 1) {  // count down 5 seconds

        // call every millisecond
         public void onTick(long millisUntilFinished) {

             if(millisUntilFinished % 1000 == 0)    // every second
                 onSecondTick(millisUntilFinished);

             if(!isStill) {
                 state = 1;     // subject is probably fine, start waiting for free fall again
             }
             else {
                 state = 0;     // subject has fallen, distress signal will be asserted
             }
         }

         // call every second
         public void onSecondTick(long millisUntilFinished) {
             Log.d(TAG, "state: " + state + " " + "Time elapsed since impact: " + (5 - millisUntilFinished/1000) + " seconds");
         }

         public void onFinish() {
             Log.d(TAG, "state: " + state + " " + "5 seconds has passed and subject has not moved.");
             timeUp = true;
         }
    };


    debounceTimer = new CountDownTimer(1000, 1000) {

        // call every millisecond
         public void onTick(long millisUntilFinished) {

         }

         public void onFinish() {
             Log.d(TAG, "state: " + state + " 1 second has passed to let subject settle.");
             state = 4;
         }     
    };

}

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
    super.onStartCommand(intent, flags, startId);
    Log.d(TAG, "onStart");

    handler = new Handler(){

        @Override
        public void handleMessage(Message msg) {
            // TODO Auto-generated method stub
            super.handleMessage(msg);
        }

    };

    reporter = new Thread(new Runnable(){
        public void run() {
            while(true)
            {
                   try {
                    Thread.sleep(1000);         // execute every second
                    handler.sendEmptyMessage(0);
                    // TO DO
                    if(fallen) {
                        // send distress signal
                        getApplicationContext().sendBroadcast(new Intent("distress"));
                        Log.d(TAG, "distress signal");
                    }
                    else {
                        // send fine signal
                        getApplicationContext().sendBroadcast(new Intent("fine"));
                        Log.d(TAG, "fine signal");
                    }         
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }
    });

    reporter.start();
    SensorTask st = new SensorTask();
    st.execute(null, null, null);

    return super.onStartCommand(intent, flags, startId);  
}

@Override
public IBinder onBind(Intent arg0) {
    // TODO Auto-generated method stub

    return null;
}

public class SensorTask extends AsyncTask<Void, Void, Void> implements SensorEventListener{

    private void initSensors() {
        mSensorManager = (SensorManager) DetectionService.this.getSystemService(SENSOR_SERVICE);

        accSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        linAccSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_LINEAR_ACCELERATION);
        gyroSensor = mSensorManager.getDefaultSensor(Sensor.TYPE_GYROSCOPE);

        mSensorManager.registerListener(this, accSensor,
                SensorManager.SENSOR_DELAY_FASTEST);

        mSensorManager.registerListener(this, gyroSensor,
                SensorManager.SENSOR_DELAY_FASTEST);
    }

    @Override
    public void onAccuracyChanged(Sensor arg0, int arg1) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        // TODO Auto-generated method stub
        switch(state) {
        case 0: 
            Log.d(TAG, "state: " + state + " fallen: " + fallen);
            fallen = true;
            break;
        case 1: // detecting free fall
            switch(event.sensor.getType()) {
            case(Sensor.TYPE_ACCELEROMETER): 

                if(detectFreeFall(event)) {
                    // free fall detected
                    state = 2;      // start detecting impact
                }

                break;
            default:
                break;
            }
        break;

        case 2: // detecting impact
            switch(event.sensor.getType()) {
            case(Sensor.TYPE_ACCELEROMETER): 

                if(detectImpact(event)) {
                    // impact detected
                    state = 3;
                }

                break;
            default:
                break;
            }
        break;

        case 3: // waiting 1 second for phone to settle
            debounceTimer.start();      // filter out the 1st second after impact to let the phone's position settle
            break;

        case 4: // detecting stillness
            debounceTimer.cancel();
            switch(event.sensor.getType()) {
            case(Sensor.TYPE_GYROSCOPE): 
                if(!detectMovementGyro(event)) {
                    stillnessTimer.cancel();    // significant change in orientation detected, stop the timer
                } 
                else {
                    stillnessTimer.start();
                }

                break;
            default:
                break;
            }
        break;

        default:
            break;

        }   
    }

    private boolean detectMovementGyro(SensorEvent event) {
        float gyroX = event.values[0];
        float gyroY = event.values[1];
        float gyroZ = event.values[2];

        float sqrMag = calcSqrMagnitude(gyroX, gyroY, gyroZ);

        Log.d(TAG, "state: " + state + " gyro sqr mag: " + sqrMag);
        Log.d(TAG, "state: " + state + " gyro: (" + gyroX + ", " + gyroY + ", " + gyroZ + ")");

        if( (sqrMag > 0.2f)) {  // placeholder test value for now
            return true;
        }

        return false;
    }

    private boolean detectImpact(SensorEvent event) {

        float accX = event.values[0];
        float accY = event.values[1];
        float accZ = event.values[2];

        float sqrMag = calcSqrMagnitude(accX, accY, accZ);

        Log.d(TAG, "state: " + state + " acc sqr mag: " + sqrMag);

        if(sqrMag > (IMPACT_THRESHOLD_MULTIPLIER * g_2)) {
            return true;
        }

        return false;   
    }

    private boolean detectFreeFall(SensorEvent event) {

        float accX = event.values[0];
        float accY = event.values[1];
        float accZ = event.values[2];

        float sqrMag = calcSqrMagnitude(accX, accY, accZ);

        Log.d(TAG, "state: " + state + " acc sqr mag: " + sqrMag);

        if(sqrMag < (FREEFALL_THRESHOLD_MULTIPLIER * g_2)) {
            return true;
        }

        return false;   
    }

    public float calcSqrMagnitude(float x, float y, float z) {
        return (float) ( Math.pow(x, 2) + Math.pow(y, 2) + Math.pow(z, 2) );
    }

    @Override
    protected Void doInBackground(Void... params) {

        initSensors();

        return null;
    }
}

}

如果它有助于说明那里应该发生什么,这是我的ASM图表http://imgur.com/a6UcVPa 代码中的实现有点不同;我试着让它等待1秒钟,粗略地过滤掉装置撞击地面的任何动作,而不是作为坠落者的实际移动。

所以我想我的问题/请求是:我的方法有什么问题吗?有人能看出我是否有任何明显的noobie错误吗?

其他信息:在将SensorEventListener组件迁移到AsyncTask之前,服务卡在state = 4中。

0 个答案:

没有答案