/*
* wiigee - accelerometerbased gesture recognition
* Copyright (C) 2007, 2008, 2009 Benjamin Poppinga
*
* Developed at University of Oldenburg
* Contact: wiigee@benjaminpoppinga.de
*
* This file is part of wiigee.
*
* wiigee is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
package org.wiigee.filter;
/**
*
* This filter removes every acceleration that happens fast or
* suddenly (like e.g. a short hit). Remember: It _passes_ acceleration
* with a slight variety.
*
* @author Benjamin 'BePo' Poppinga
*/
public class LowPassFilter extends Filter {
private double factor;
private double[] prevAcc;
public LowPassFilter() {
super();
this.factor = 0.01;
this.reset();
}
public LowPassFilter(double factor) {
super();
this.factor = factor;
this.reset();
}
@Override
public void reset() {
this.prevAcc = new double[] {0.0, 0.0, 0.0};
}
@Override
public double[] filterAlgorithm(double[] vector) {
double[] retVal = new double[3];
retVal[0] = vector[0] * this.factor + this.prevAcc[0] * (1.0 - this.factor);
retVal[1] = vector[1] * this.factor + this.prevAcc[1] * (1.0 - this.factor);
retVal[2] = vector[2] * this.factor + this.prevAcc[2] * (1.0 - this.factor);
this.prevAcc = retVal;
return retVal;
}
}