Smoothing data from a sensor

Question

I have a 3D sensor which measures v(x,y,z) data. I\'m only using the x and y data. Smoothing only x and y would be enough.

If I use a log to show the data, it shows

Answer 1

So I came here looking to solve the same problem (sensor input smoothing in Android) and here's what I came up with:

/*
 * time smoothing constant for low-pass filter
 * 0 ≤ α ≤ 1 ; a smaller value basically means more smoothing
 * See: http://en.wikipedia.org/wiki/Low-pass_filter#Discrete-time_realization
 */
static final float ALPHA = 0.2f;

protected float[] accelVals;

public void onSensorChanged(SensorEvent event) {
    if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER)
        accelVals = lowPass( event.values, accelVals );

    // use smoothed accelVals here; see this link for a simple compass example:
    // http://www.codingforandroid.com/2011/01/using-orientation-sensors-simple.html
}

/**
 * @see http://en.wikipedia.org/wiki/Low-pass_filter#Algorithmic_implementation
 * @see http://en.wikipedia.org/wiki/Low-pass_filter#Simple_infinite_impulse_response_filter
 */
protected float[] lowPass( float[] input, float[] output ) {
    if ( output == null ) return input;

    for ( int i=0; i

Thank you @slebetman for pointing me toward the Wikipedia link, which after a little reading drew me to the algorithm on the wikipedia Low-pass filter article. I won't swear I have the best algorithm (or even right!) but anecdotal evidence seems to indicate it's doing the trick.