Accuracy problems using accelerometer android

问题:

I'm developing a simple counter app which counts when the user move their phone along the x axis(positive or negative) about 90 degrees.i'm using the accelerometer for measuring the acceleration cause by moving the phone and using this for counting. but there is a problem,the accuracy is not good,sometimes it doesn't count and sometimes it count twice. this is my code,i want to know if there is a way to get good accuracy?

@Override
protected void onResume() {
    super.onResume();
    SnManager.registerListener(this,acc,SensorManager.SENSOR_DELAY_NORMAL);
}
@Override
public void onSensorChanged(SensorEvent event) {
    if(!stop) {
        if (event.values[0] > 14) {
            Count++;
            txt_count.setText("" + Count);
            values.add("OK");
        }
        values.add(""+event.values[0]);
        lst.invalidate();
    }
}

回答1:

You can check the event timestamp to determine if it's an already measured value, but I would suggest that you implement a kind of smoothing for example a rolling average over the last 3-5 values. That makes your values a lot smoother and better to handle. Here is an example with double values, you can change to whatever your want: ´

public class Rolling {
    private int size;
    private double total = 0d;
    private int index = 0;
    private double samples[];
    public Rolling(int size) {
        this.size = size;
        samples = new double[size];
        for (int i = 0; i < size; i++) samples[i] = 0d;
    }

    public void add(double x) {
        total -= samples[index];
        samples[index] = x;
        total += x;
        if (++index == size) index = 0; 
    }

    public double getAverage() {
        return total / size;
    }   
}

´

Do you need further help?