I just registered to show some love for this code sample, it helped me greatly because I needed to the phone's angle to filter out gravity from the accelerometer and this code helped me do just that.
Specifically using it as a base it can be reconfigured into:
Using java Syntax Highlighting
//put these in variables so they can be adjusted for device calibration
private double gravityConstantX = SensorManager.GRAVITY_EARTH;
private double gravityConstantY = SensorManager.GRAVITY_EARTH;
private double gravityConstantZ = SensorManager.GRAVITY_EARTH;
double accX = -x/gravityConstantX;
double accY = -y/gravityConstantY;
double accZ = -z/gravityConstantZ;
double totAcc = Math.sqrt((accX*accX)+(accY*accY)+(accZ*accZ));
double tiltXInGs = Math.asin(accX/totAcc);
double tiltYInGs = Math.asin(accY/totAcc);
double tiltZInGs = Math.asin(accZ/totAcc);
//convert to rads, or something close, end up with the opposite angle
double tiltX = Math.sin(tiltXInGs);
double tiltY = Math.sin(tiltYInGs);
double tiltZ = Math.sin(tiltZInGs);
//use these angles to calculate gravity * -1
Double gx = (gravityConstantX * Math.sin(tiltX));
Double gy = (gravityConstantY * Math.sin(tiltY));
Double gz = (gravityConstantZ * Math.sin(tiltZ));
//add the resulting negative gravity and convert the result (acceleration of the phone relative to the ground)
// to centimeters a second
Integer resultx = metersToCentimeters(x + gx);
Integer resulty = metersToCentimeters(y + gy);
Integer resultz = metersToCentimeters(z + gz);
//assuming the phone is held on it's back it seems to need this correction
resultz -= 100;
Parsed in 0.034 seconds, using
GeSHi 1.0.8.4
- private Integer metersToRoundedOffCentimeters(Double meters) {
- Integer centimeters = (int) Math.round(100 * meters);
- return centimeters;
- }
The math is more advanced then I currently know, so I don't exactly understand how it works. I discovered the "double tiltX = Math.sin(tiltXInGs);" line accidentally while trying to work out how to convert it into angles.
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