android - Filtering accelerometer data noise

Question

How do I filter noise of the accelerometer data in Android? I would like to create a high-pass filter for my sample data so that I could eliminate low frequency components and focus on the high frequency components. I have read that Kalman filter might be the best candidate for this, but how do I integrate or use this method in my application which will mostly written in Android Java? or can it be done in the first place? or through Android NDK? Is there by any chance that this can be done in real-time?

Any idea will be much appreciated. Thank you!

Answer 1

The samples from Apple's SDK actually implement the filtering in an even simpler way which is by using ramping:

//ramp-speed - play with this value until satisfied
const float kFilteringFactor = 0.1f;

//last result storage - keep definition outside of this function, eg. in wrapping object
float accel[3]; 

//acceleration.x,.y,.z is the input from the sensor

//result.x,.y,.z is the filtered result

//high-pass filter to eliminate gravity
accel[0] = acceleration.x * kFilteringFactor + accel[0] * (1.0f - kFilteringFactor);
accel[1] = acceleration.y * kFilteringFactor + accel[1] * (1.0f - kFilteringFactor);
accel[2] = acceleration.z * kFilteringFactor + accel[2] * (1.0f - kFilteringFactor);
result.x = acceleration.x - accel[0];
result.y = acceleration.y - accel[1];
result.z = acceleration.z - accel[2];