Edit Question - KnowledgeHub

Title Body

I am developing application for car acceleration tracking. I used standard accelerometer, calibrating it in specific position beforehand. Then, assuming phone's orientation is not changing, I logged the accelerometer data for a specified time and calculated move parameters, one of which is the car's speed at the end of the test. It works rather well, on a straight, horizontal road: error of a few percent. But then I found out, that in API-level 10 there is a virtual sensor called TYPE_LINEAR_ACCELERATION and, as far as I understand, it must do what I need: filter gravity, orientation changes - so I may use it and get pure linear acceleration of mobile device. BUT in real life.. I made a simple application, that does a little test: //public class Accelerometer implements SensorEventListener { ... public void onSensorChanged(SensorEvent se) { if(!active) return; lastX = se.values[SensorManager.DATA_X]; lastY = se.values[SensorManager.DATA_Y]; lastZ = se.values[SensorManager.DATA_Z]; long now = System.currentTimeMillis(); interval = now - lastEvetn; lastEvetn = now; out.write(Float.toString(lastX) + ";" + Float.toString(lastY) + ";" + Float.toString(lastZ) + ";" + Long.toString(interval) + "\n"); } I bind a listener with the following parameters: mSensorManager.registerListener(linAcc, mSensorManager.getDefaultSensor(Sensor.TYPE_LINEAR_ACCELERATION), SensorManager.SENSOR_DELAY_GAME); It works OK, but when I analyzed data dump, calculating speed like V = V0 + AT , where V0 = 0 at first, then - speed of interval before this, A = acceleration (SQRT (x*x+y*y+z*z)) (t = time of interval), eventually I get a very low speed - three times less than real speed. Changing Sens

Tags (comma-separated) Cancel