title: A physical Accelerometer exists but virtual Significant Motion Sensor doesn't exist
body: <p>I have an Xperia Z phone which runs Android 5.1 on.</p>
  
  <p>When checking the sensors that are present I get the below results:</p>
  
  <pre><code>mSensorAccelerometer: {Sensor name="MPL Accelerometer", vendor="Invensense", version=1, type=1, maxRange=19.6133, resolution=0.038344003, power=0.139, minDelay=5000}
  mSensorLinearAcceleration: {Sensor name="MPL Linear Acceleration", vendor="Invensense", version=1, type=10, maxRange=19.6133, resolution=0.038344003, power=16.239, minDelay=5000}
  
  mSensorSignificantMotion: null
  mSensorStepDetector: null
  mSensorStepCounter: null
  </code></pre>
  
  <p>So, there are a physical <code>Accelerometer</code> and a <code>Linear Acceleration</code> composite sensors.</p>
  
  <p>Signification Sensor, Step Detector and Step Counter composite sensors seem as not present. However <a href="https://source.android.com/devices/sensors/sensor-types#significant_motion" rel="nofollow noreferrer">the documentation</a> writes that <code>Underlying physical sensor: Accelerometer</code> for these three sensors.</p>
  
  <p>Is there any chance to use these three sensors?</p>
  
  <p>Why do they seem as <code>null</code> although they are software-based (virtual) sensors?</p>