Question about the rotation of X axis on Android

问题

I want to detect the correct rotations around X axis with Android sensors. After googling, I find this code:

   public void onSensorChanged(SensorEvent event) {
   Sensor sensor = event.sensor;
   switch(sensor.getType()) {
   case Sensor.TYPE_ACCELEROMETER:
    mAcc = event.values.clone();
    break;
   case Sensor.TYPE_MAGNETIC_FIELD:
    mMag = event.values.clone();
    break;
   }
   if (mAcc == null || mMag == null) return;

   float R[] = new float[9];
   if (SensorManager.getRotationMatrix(R, null, mAcc, mMag)) {
    SensorManager.getOrientation(R, mOrientation);
   }
  }

mOrientation[1] represents the radians around the X axis. However, the value is very odd.

When the phone lies flat top up on the table, it's 0.
When the head of the phone pointing to the ground, it's PI/2.
When the phone lies flat bottom up on the table, it's 0 again.
When the head of the phone pointing to the sky, it -PI/2.

The states between 1,2 have the same rotation values of those between 2,3. How could I tell which state my phone is in?

回答1:

Please verify your readings.

The signs & range you report are completely out of sync with
what is expected on an android device.

developer.android.com/reference/android/hardware/Sensor.html#TYPE_ORIENTATION

Note: This sensor type exists for legacy reasons, please use getRotationMatrix() in conjunction with remapCoordinateSystem() and getOrientation() to compute these values instead.

Regards
CVS@2600Hertz

来源：https://stackoverflow.com/questions/3282401/question-about-the-rotation-of-x-axis-on-android

标签

android

sensor