Android Open Source - AndroidLibraryProject Accelerometer Data Analysis

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The source code is released under:

Apache License

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Java Source Code

/*
 * Copyright (c) 2013 by CDAC Chennai /*  ww  w.j a  va  2  s.  c  om*/
 * 
 * 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.
 *  
 * @File        AccelerometerDataAnalysis
 * @Created:    18.11.2013
 * @author:     Prasenjit
 * Last Change: 18.11.2013 by Prasenjit
 */



package com.contextawareframework.dataanalysis;

import android.content.Context;


/**
 * This class help the user to select either low pass or high pass filter from the Accelerometer
 * Sensor in Android. It returns the float array with first three values as low pass filter
 * and the next three value as high pass filter.
 */
public class AccelerometerDataAnalysis {

  Context localContext;
  /**
   * Default Constructor
   */
  public AccelerometerDataAnalysis(Context contextFromMainApp)
  {
    localContext = contextFromMainApp;
  }

  /**
   * Method to perform low pass filter and high pass filter on Accelerometer data.
   */
  public float[] AccelDataAnalysis(float x,float y, float z)
  {  
    float [] values = {0,0,0,0,0,0} ;
    try{
      //ContextAwareFunction caf = new ContextAwareFunction(localContext);
      // alpha is calculated as t / (t + dT)
      // with t, the low-pass filter's time-constant
      // and dT, the event delivery rate

      final float alpha = (float) 0.75;

      float gravity[]={0,0,0};

      // Isolate the force of gravity with the low-pass filter.
      gravity[0] = alpha * gravity[0] + (1 - alpha) * x;
      gravity[1] = alpha * gravity[1] + (1 - alpha) * y;
      gravity[2] = alpha * gravity[2] + (1 - alpha) * z;

      // Assigning values that can be used in Application level directly for any additional feature
      values[0] = gravity[0];
      values[1] = gravity[1];
      values[2] = gravity[2];

      // Remove the gravity contribution with the high-pass filter.

      float linear_acceleration[]= {0,0,0};

      // Assigning values that can be used in Application level directly for any additional feature
      linear_acceleration[0] = x - gravity[0];
      linear_acceleration[1] = y - gravity[1];
      linear_acceleration[2] = z - gravity[2];

      values[3] = linear_acceleration[0];
      values[4] = linear_acceleration[1];
      values[5] = linear_acceleration[2];
      //Log.d("Debug","X coordinate value = " + event.values[0]);
      //Log.d("Debug","Z coordinate value = " + event.values[2]);

    }
    catch(Exception e)
    {
      e.printStackTrace();
    }
    return  values;
  }

}

Java Source Code List