Android Open Source - Fall_Prevention_2013 Calibration Thread

From Project

Back to project page Fall_Prevention_2013.
License

The source code is released under:
Apache License
If you think the Android project Fall_Prevention_2013 listed in this page is inappropriate, such as containing malicious code/tools or violating the copyright, please email info at java2s dot com, thanks.
Java Source Code

/*******************************************************************************
 * Licensed to UbiCollab.org under one or more contributor
 * license agreements.  See the NOTICE file distributed 
 * with this work for additional information regarding
 * copyright ownership. UbiCollab.org licenses this file
 * to you 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
 * /*  w  w w.j a  v  a  2 s. c  om*/
 *     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 ntnu.stud.valens.stepdetector.calibration;

import java.util.ArrayList;
import java.util.List;

import ntnu.stud.valens.stepdetector.Methods;
import ntnu.stud.valens.stepdetector.Values;


import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;

/**
 * This thread handles calibration. When it is launched, it accesses the
 * accelerometer sensor and stores data for a period of time. At the end of the
 * period, it makes a sound, and then calculates mean and std for the data. This
 * is done by performing the ordinary first steps for step detection: Finding
 * vector lengths, smoothing, calculating peak strength. Finally it calculates
 * the mean and std for the calculated data.
 * 
 * @author Elias
 * 
 */
public class CalibrationThread implements Runnable, SensorEventListener {

  private List<Float> mVectorLengths;
  private SensorManager mSensorManager;
  private Sensor mAccSensor;
  private CalibrationActivity context;
  private Long startTime;

  /**
   * Constructor.
   * 
   * @param c
   *            - The CalibrationActivity that the Timer belongs to. This is
   *            need to use the playSound() function in the
   *            CalibrationActivity during run().
   */
  public CalibrationThread(CalibrationActivity context) {
    this.context = context;
    mVectorLengths = new ArrayList<Float>();
  }

  /**
   * Started at launch of thread. Starts gathering data.
   */
  @Override
  public void run() {
    // Find and register sensor
    mSensorManager = (SensorManager) context
        .getSystemService(Context.SENSOR_SERVICE);
    for (Sensor sensor : mSensorManager
        .getSensorList(Sensor.TYPE_ACCELEROMETER)) {
      if (sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
        mAccSensor = sensor;
      }
    }

    mSensorManager.registerListener(this, mAccSensor,
        SensorManager.SENSOR_DELAY_GAME);
    // Find the start time of calibration calculation
    startTime = System.currentTimeMillis();
  }

  // We don't really care about this, it just has to be implemented because of
  // the SensorListener-interface
  @Override
  public void onAccuracyChanged(Sensor arg0, int arg1) {
  }

  /**
   * Fired by a SensorChange-event. Parameter is provided by the system.
   */
  @Override
  public void onSensorChanged(SensorEvent event) {
    mVectorLengths.add(Methods.calculateVectorLength(event.values));
    // If calibration has run for a long enough time, stop gathering
    // data
    if (System.currentTimeMillis() - startTime > Values.CAL_TIME) {
      finish();
    }
  }

  /**
   * Called when enough data has been gathered. It performs the ordinary steps
   * for step detection, and calculates mean and std. Finally, it fires
   * finishCalibration() in the CalibrationActivity.
   */
  private void finish() {
    // Stop listening to sensor input
    mSensorManager.unregisterListener(this);
    // Calculate mean and std
    List<Float> smoothedData = Methods.smooth(mVectorLengths,
        Values.SMOOTHING_WINDOW);
    List<Float> peakStrengths = Methods
        .calculatePeakStrengths(smoothedData);
    Double mean = Methods.calculateMean(peakStrengths);
    Double std = Methods.calculateStd(peakStrengths, mean);
    // Tell the calibration activity to play a sound and store values
    context.finishCalibration(mean, std);
  }
}
Java Source Code List
