Question

我正在尝试使用智能手机的加速度计作为学校项目来构建用于跌倒检测的应用程序（因此我还有很多事情需要改进）。我正在做一些研究，发现article经过一些计算，所以我试图将其转换为一些代码。

我向一位朋友寻求帮助，他向我解释了如何进行这些计算。但是考虑到我高中毕业已经有几年了，而我的数学也不是很好，所以我确定我做错了什么。所以我期待有人可以帮我忙。

如果有人发现任何错误，这就是我所需要的，我已经拥有的。

return Math.abs(x) + Math.abs(y) + Math.abs(z);

    double anX = this.accelerometerValues.get(size -2).get(AccelerometerAxis.X) * this.accelerometerValues.get(size -1).get(AccelerometerAxis.X);
    double anY = this.accelerometerValues.get(size -2).get(AccelerometerAxis.Y) * this.accelerometerValues.get(size -1).get(AccelerometerAxis.Y);
    double anZ = this.accelerometerValues.get(size -2).get(AccelerometerAxis.Z) * this.accelerometerValues.get(size -1).get(AccelerometerAxis.Z);
    double an = anX + anY + anZ;

    double anX0 = Math.pow(this.accelerometerValues.get(size -2).get(AccelerometerAxis.X), 2);
    double anY0 = Math.pow(this.accelerometerValues.get(size -2).get(AccelerometerAxis.Y), 2);
    double anZ0 = Math.pow(this.accelerometerValues.get(size -2).get(AccelerometerAxis.Z), 2);
    double an0 = Math.sqrt(anX0 + anY0 + anZ0);

    double anX1 = Math.pow(this.accelerometerValues.get(size -1).get(AccelerometerAxis.X), 2);
    double anY1 = Math.pow(this.accelerometerValues.get(size -1).get(AccelerometerAxis.Y), 2);
    double anZ1 = Math.pow(this.accelerometerValues.get(size -1).get(AccelerometerAxis.Z), 2);
    double an1 = Math.sqrt(anX1 + anY1 + anZ1);

    double a = an / (an0 * an1);

    return (Math.pow(Math.cos(a), -1)) * (180 / Math.PI);

    double aX = this.accelerometerValues.get(0).get(AccelerometerAxis.X) * this.accelerometerValues.get(3).get(AccelerometerAxis.X);
    double aY = this.accelerometerValues.get(0).get(AccelerometerAxis.Y) * this.accelerometerValues.get(3).get(AccelerometerAxis.Y);
    double aZ = this.accelerometerValues.get(0).get(AccelerometerAxis.Z) * this.accelerometerValues.get(3).get(AccelerometerAxis.Z);

    double a0 = aX + aY + aZ;

    double a1 = (Math.sqrt(Math.pow(aX, 2)) + Math.sqrt(Math.pow(aY, 2)) + Math.sqrt(Math.pow(aZ, 2)));

    return (Math.pow(Math.cos(a0 / a1), -1)) * (180 / Math.PI);

我从第二次和第三次计算中获得了相同的回报，这似乎都不是预期的结果，但是我找不到我做错的事情。

这是该课程的代码，有关更多详细信息

import android.app.IntentService;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.support.annotation.VisibleForTesting;
import android.util.Log;
import android.widget.Toast;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import br.com.aimcol.fallalertapp.activity.FallNotificationActivity;
import br.com.aimcol.fallalertapp.model.Elderly;
import br.com.aimcol.fallalertapp.model.Person;
import br.com.aimcol.fallalertapp.model.User;
import br.com.aimcol.fallalertapp.util.AccelerometerAxis;
import br.com.aimcol.fallalertapp.util.RuntimeTypeAdapterFactory;

public class FallDetectionService extends IntentService implements SensorEventListener {


    private static final int ACCELEROMETER_SAMPLING_PERIOD = 1000000;
    private static final double CSV_THRESHOLD = 23;
    private static final double CAV_THRESHOLD = 18;
    private static final double CCA_THRESHOLD = 65.5;

    private SensorManager mSensorManager;
    private Sensor mAccelerometer;
    private User user;
    private Gson gson;

    private Long lastSentInMillis;
    private Long minTimeToNotifyAgain = 3000000L;

    private List<Map<AccelerometerAxis, Double>> accelerometerValues = new ArrayList<>();


    public FallDetectionService() {
        super(".FallDetectionService");
    }

    /**
     * Creates an IntentService.  Invoked by your subclass's constructor.
     *
     * @param name Used to name the worker thread, important only for debugging.
     */
    public FallDetectionService(String name) {
        super(name);
    }

    @Override
    public void onCreate() {
        super.onCreate();
    }

    @Override
    public IBinder onBind(Intent intent) {
        // TODO: Return the communication channel to the service.
        throw new UnsupportedOperationException("Not yet implemented");
    }

    @Override
    public final void onAccuracyChanged(Sensor sensor,
                                        int accuracy) {
    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        // Axis of the rotation sample, not normalized yet.
        double x = event.values[0];
        double y = event.values[1];
        double z = event.values[2];

        if (this.isFallDetected(x, y, z)) {
            if (this.isOkayToNotifyAgain()) {
                this.lastSentInMillis = System.currentTimeMillis();
                Toast.makeText(this, "Fall", Toast.LENGTH_LONG).show();
                FallNotificationActivity.startFallNotificationActivity(this, this.gson.toJson(this.user));
            }
        }
    }

    private boolean isFallDetected(double x,
                                double y,
                                double z) {

        double acceleration = this.calculateAcceleration(x, y, z);// - SensorManager.GRAVITY_EARTH;
        this.addAccelerometerValuesToList(x, y, z, acceleration);

        String msg = new StringBuilder("x: ").append(x).append(" y: ").append(y).append(" z: ").append(z).append(" acc: ").append(acceleration).toString();
        Log.d("FDS-Acc-Values", msg);

        if (acceleration > CSV_THRESHOLD) {
//            double angleVariation = this.calculateAngleVariation();
//            if (angleVariation > CAV_THRESHOLD) {
//                double changeInAngle = this.calculateChangeInAngle();
//                if (changeInAngle > CCA_THRESHOLD) {
                    Log.d("FDS-Fall-Happened", msg);
                   return true;
//                }
//            }
        }
        return false;
    }

    private void addAccelerometerValuesToList(double x,
                                              double y,
                                              double z,
                                              double acceleration) {
        if(this.accelerometerValues.size() >= 4) {
            this.accelerometerValues.remove(0);
        }
        Map<AccelerometerAxis, Double> map = new HashMap<>();
        map.put(AccelerometerAxis.X, x);
        map.put(AccelerometerAxis.Y, y);
        map.put(AccelerometerAxis.Z, z);
        map.put(AccelerometerAxis.ACCELERATION, acceleration);
        this.accelerometerValues.add(map);
    }

    private double calculateAcceleration(double x,
                                         double y,
                                         double z) {
        return Math.abs(x) + Math.abs(y) + Math.abs(z);
    }

    private double calculateAngleVariation() {
        int size = this.accelerometerValues.size();
        if (size < 2){
            return -1;
        }

        double anX = this.accelerometerValues.get(size -2).get(AccelerometerAxis.X) * this.accelerometerValues.get(size -1).get(AccelerometerAxis.X);
        double anY = this.accelerometerValues.get(size -2).get(AccelerometerAxis.Y) * this.accelerometerValues.get(size -1).get(AccelerometerAxis.Y);
        double anZ = this.accelerometerValues.get(size -2).get(AccelerometerAxis.Z) * this.accelerometerValues.get(size -1).get(AccelerometerAxis.Z);
        double an = anX + anY + anZ;

//        double an = this.accelerometerValues.get(size -2).get(AccelerometerAxis.ACCELERATION) * this.accelerometerValues.get(size -1).get(AccelerometerAxis.ACCELERATION);

        double anX0 = Math.pow(this.accelerometerValues.get(size -2).get(AccelerometerAxis.X), 2);
        double anY0 = Math.pow(this.accelerometerValues.get(size -2).get(AccelerometerAxis.Y), 2);
        double anZ0 = Math.pow(this.accelerometerValues.get(size -2).get(AccelerometerAxis.Z), 2);
        double an0 = Math.sqrt(anX0 + anY0 + anZ0);

        double anX1 = Math.pow(this.accelerometerValues.get(size -1).get(AccelerometerAxis.X), 2);
        double anY1 = Math.pow(this.accelerometerValues.get(size -1).get(AccelerometerAxis.Y), 2);
        double anZ1 = Math.pow(this.accelerometerValues.get(size -1).get(AccelerometerAxis.Z), 2);
        double an1 = Math.sqrt(anX1 + anY1 + anZ1);

        double a = an / (an0 * an1);

        return (Math.pow(Math.cos(a), -1)) * (180 / Math.PI); //cosseno inverso? Ou cosseno ^-1?
    }

    private double calculateChangeInAngle() {
        int size = this.accelerometerValues.size();
        if (size < 4){
            return -1;
        }
        double aX = this.accelerometerValues.get(0).get(AccelerometerAxis.X) * this.accelerometerValues.get(3).get(AccelerometerAxis.X);
        double aY = this.accelerometerValues.get(0).get(AccelerometerAxis.Y) * this.accelerometerValues.get(3).get(AccelerometerAxis.Y);
        double aZ = this.accelerometerValues.get(0).get(AccelerometerAxis.Z) * this.accelerometerValues.get(3).get(AccelerometerAxis.Z);

        double a0 = aX + aY + aZ;

        double a1 = (Math.sqrt(Math.pow(aX, 2)) + Math.sqrt(Math.pow(aY, 2)) + Math.sqrt(Math.pow(aZ, 2)));

        return (Math.pow(Math.cos(a0 / a1), -1)) * (180 / Math.PI);
    }

    @Override
    protected void onHandleIntent(@Nullable Intent intent) {
        if (this.user == null) {
            String userJson = intent.getStringExtra(User.USER_JSON);
            this.user = this.gson.fromJson(userJson, User.class);
        }
    }

    @Override
    public int onStartCommand(Intent intent,
                              int flags,
                              int startId) {

        if (this.gson == null) {
            RuntimeTypeAdapterFactory<Person> runtimeTypeAdapterFactory = RuntimeTypeAdapterFactory
                    .of(Person.class, "type")
                    .registerSubtype(Elderly.class, Elderly.class.getSimpleName());
            this.gson = new GsonBuilder().registerTypeAdapterFactory(runtimeTypeAdapterFactory).create();
        }

        if (this.user == null) {
            String userJson = intent.getStringExtra(User.USER_JSON);
            this.user = this.gson.fromJson(userJson, User.class);
        }

        this.mSensorManager = (SensorManager) super.getSystemService(Context.SENSOR_SERVICE);
        this.mAccelerometer = this.mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        if (this.mAccelerometer == null) {
            throw new RuntimeException("Acelerometro não encontrado");
        }

        this.mSensorManager.registerListener(this, this.mAccelerometer, ACCELEROMETER_SAMPLING_PERIOD);

        return Service.START_STICKY;
    }

    private boolean isOkayToNotifyAgain() {
        return this.lastSentInMillis == null || (this.lastSentInMillis + this.minTimeToNotifyAgain) < System.currentTimeMillis();
    }

    public static void startFallDetectionService(String userJson,
                                                 Context context) {

        Intent fallDetectionServiceIntent = new Intent(context, FallDetectionService.class);
        fallDetectionServiceIntent.putExtra(User.USER_JSON, userJson);
        context.startService(fallDetectionServiceIntent);
    }

    @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
    protected boolean testFallDetection(List<Map<AccelerometerAxis, Double>> values) {
        for (Map<AccelerometerAxis, Double> value : values) {
            if (this.isFallDetected(
                    value.get(AccelerometerAxis.X),
                    value.get(AccelerometerAxis.Y),
                    value.get(AccelerometerAxis.Z))) {

                return true;
            }
        }
        return false;
    }
}

Ps：对不起，如果我做错了。英语不是我的母语，我有点生疏。

Ps2：对不起，我的变量名。

Ps3：该代码位于github上，如果您想看一下其余的代码，或者如果不想在这里发表回复，而想提出拉取请求或其他任何东西，请随时发问。< / p>

Answer 1

这个问题在这里可能不合适。 SO并不是要用作代码审查站点。

以下是要考虑的一些评论：

您列出的第一个公式不是您在代码中表达的。公式中没有平方根或平方和，但是出于某种原因将它们放入代码中。文章说SV应该是线性加速度矢量分量的绝对值之和。这不是您的代码所说的。
我不清楚第二个公式中n和n + 1的含义。是那些连续的时间点吗？两个向量的点积很容易计算-但是对于两个向量呢？
第三个公式要求在四秒钟的窗口内平均加速度矢量。我看不到在任何地方做。平均值中涉及的向量数量取决于您的采样率。

我建议您再读几遍。

我还建议您将它们封装到函数中，并为它们编写一些良好的单元测试。看看是否可以重现论文的结果。

Android-加速度计跌落检测算法

1 个答案: