Can anyone tell me how i get toast when mobile falls down?

问题

I am making an android project to detect when mobile fall down, can anyone tell me which sensor should I use in my app, I know accelerometer will use for this kind of purpose, but accelerometer can also detect when I shake the phone in my hand and I want to get the toast only when the mobile falls down. here is my code:

int count = 1;
    private boolean init;
    private Sensor mySensor;
    private SensorManager SM;
    private float x1, x2, x3;
    private static final float ERROR = (float) 7.0;
    private static final float SHAKE_THRESHOLD = 15.00f; // m/S**2
    private static final int MIN_TIME_BETWEEN_SHAKES_MILLISECS = 1000;
    private long mLastShakeTime;
       public void onSensorChanged(SensorEvent event) {

            if (event.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {

                long curTime = System.currentTimeMillis();
                if ((curTime - mLastShakeTime) > MIN_TIME_BETWEEN_SHAKES_MILLISECS) {

                    float x = event.values[0];
                    float y = event.values[1];
                    float z = event.values[2];

                    double acceleration = Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2)
                            + Math.pow(z, 2))
                            - SensorManager.GRAVITY_EARTH;
                    Log.d("mySensor", "Acceleration is " + acceleration + "m/s^2");

                    if (acceleration > SHAKE_THRESHOLD) {
                        mLastShakeTime = curTime;
                        Toast.makeText(getApplicationContext(), "FALL DETECTED",
                                Toast.LENGTH_LONG).show();
    } } }}

回答1:

There is no "Fall Sensor", your guess in using the accelerometer is right. Record and measure the accelerometer data when it falls and deduct a model from there.

回答2:

You have to use accelerometer. But it will detect very small movement.

The only way to do is , get the difference between two readings on change of state.

If its very very high, the mobile has traveled a longer distances say fell down from hand, or change an abnormal position say a shock.

回答3:

For this we have to use little bit of Physics, any object falling under the influence of gravity has an acceleration of 9.8 m/s/s, downward (on Earth). SO with this knowledge we can get the downward direction speed
1)based on the axis(Y-axis) using accelerometer check it is downward and
2) check if it is equal to this 9.8 m/s constant and also check the

if the fall speed is approx near 9.8 m/s show the toast

回答4:

Hi all i done this by myself a little change was get me rid of this , that is just taking two variable set those values negative and call them as threshold value of acceleration . thanks everyone

来源：https://stackoverflow.com/questions/36540058/can-anyone-tell-me-how-i-get-toast-when-mobile-falls-down

标签

android

android-sensors