如何检测行走与Android加速度计 [英] How to detect walking with Android accelerometer

问题描述

我正在写一个应用程序，我的目标是当用户走到检测。 我使用的是卡尔曼滤波器是这样的：

I'm writing an application and my aim is to detect when a user is walking. I'm using a Kalman filter like this:

float kFilteringFactor=0.6f;

        gravity[0] = (accelerometer_values[0] * kFilteringFactor) + (gravity[0] * (1.0f - kFilteringFactor));
        gravity[1] = (accelerometer_values[1] * kFilteringFactor) + (gravity[1] * (1.0f - kFilteringFactor));
        gravity[2] = (accelerometer_values[2] * kFilteringFactor) + (gravity[2] * (1.0f - kFilteringFactor));

        linear_acceleration[0] = (accelerometer_values[0] - gravity[0]);
        linear_acceleration[1] = (accelerometer_values[1] - gravity[1]);
        linear_acceleration[2] = (accelerometer_values[2] - gravity[2]);

        float magnitude = 0.0f;
        magnitude = (float)Math.sqrt(linear_acceleration[0]*linear_acceleration[0]+linear_acceleration[1]*linear_acceleration[1]+linear_acceleration[2]*linear_acceleration[2]);
        magnitude = Math.abs(magnitude);
if(magnitude>0.2)
  //walking

数组重力[]与0初始化。

The array gravity[] is initialized with 0s.

我可以检测当用户行走或不（看着加速度矢量的大小的值），​​但我的问题是，当一个用户是不是正和他移动电话，似乎他走

I can detect when a user is walking or not (looking at the value of the magnitude of the acceleration vector), but my problem is that when a user is not walking and he moves the phones, it seems that he is walking.

我使用的是正确的过滤器？

Am I using the right filter?

时的正确观看向量的唯一的幅度还是有我看单价值观

Is it right to watch only the magnitude of the vector or have I to look at the single values ??

推荐答案

有关检测走我用应用于从加速度平滑信号的导数。当该导数大于阈值I可以建议，这是一个步骤。但我想，这不是最好的做法，而且当手机放在裤子口袋里它仅适用。

For walking detection I use the derivative applied to the smoothed signal from accelerometer. When the derivative is greater than threshold value I can suggest that it was a step. But I guess that it's not best practise, furthermore it only works when the phone is placed in a pants pocket.

下面code是在这个程序中使用 HTTPS ：？//play.google.com/store/apps/details ID = com.tartakynov.robotnoise

The following code was used in this app https://play.google.com/store/apps/details?id=com.tartakynov.robotnoise

    @Override
    public void onSensorChanged(SensorEvent event) {
        if (event.sensor.getType() != Sensor.TYPE_ACCELEROMETER){
            return;
        }
        final float z = smooth(event.values[2]); // scalar kalman filter                               
        if (Math.abs(z - mLastZ) > LEG_THRSHOLD_AMPLITUDE)
        {
            mInactivityCount = 0;
            int currentActivity = (z > mLastZ) ? LEG_MOVEMENT_FORWARD : LEG_MOVEMENT_BACKWARD;                  
            if (currentActivity != mLastActivity){
                mLastActivity = currentActivity;
                notifyListeners(currentActivity);
            }                   
        } else {
            if (mInactivityCount > LEG_THRSHOLD_INACTIVITY) {
                if (mLastActivity != LEG_MOVEMENT_NONE){
                    mLastActivity = LEG_MOVEMENT_NONE;
                    notifyListeners(LEG_MOVEMENT_NONE);                                 
                }
            } else {
                mInactivityCount++;
            }
        }
        mLastZ = z;
    }

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