当您使用TYPE_MAGNETOMETER传感器，你得到的X，Y，相对于设备的方向磁场强度Z值。 我想是将这些值转换为全局参考坐标，澄清：用户需要的设备，测量这些值，比旋转设备一定程度上围绕任何轴，并得到〜相同的值。 请在下面找到类似的问题： 获得在全球坐标磁场值 我怎样才能得到磁场矢量，独立于设备的旋转？ 在这种应答样品溶液被描述（它是直线加速，但我认为这并不重要）： https://stackoverflow.com/a/11614404/2152255我用它和我的3个值，X总是很小（不认为这是正确的），Y和Z都OK，但他们还是改了一下，当我旋转设备。 怎么会调整？ 而且可以把它都会解决？ 我用简单的卡尔曼滤波器来近似测量值，因为W / O它，我得到即使设备不动安静的不同的值/旋转可言。 请在下面找到我的代码：
import android.app.Activity;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.opengl.Matrix;
import android.os.Bundle;
import android.view.View;
import android.widget.CheckBox;
import android.widget.TextView;
import com.test.statistics.filter.kalman.KalmanState;
import com.example.R;
/**
* Activity for gathering magnetic field statistics.
*/
public class MagneticFieldStatisticsGatheringActivity extends Activity implements SensorEventListener {
public static final int KALMAN_STATE_MAX_SIZE = 80;
public static final double MEASUREMENT_NOISE = 5;
/** Sensor manager. */
private SensorManager mSensorManager;
/** Magnetometer spec. */
private TextView vendor;
private TextView resolution;
private TextView maximumRange;
/** Magnetic field coordinates measurements. */
private TextView magneticXTextView;
private TextView magneticYTextView;
private TextView magneticZTextView;
/** Sensors. */
private Sensor mAccelerometer;
private Sensor mGeomagnetic;
private float[] accelerometerValues;
private float[] geomagneticValues;
/** Flags. */
private boolean specDefined = false;
private boolean kalmanFiletring = false;
/** Rates. */
private float nanoTtoGRate = 0.00001f;
private final int gToCountRate = 1000000;
/** Kalman vars. */
private KalmanState previousKalmanStateX;
private KalmanState previousKalmanStateY;
private KalmanState previousKalmanStateZ;
private int previousKalmanStateCounter = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main2);
mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
mGeomagnetic = mSensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD);
vendor = (TextView) findViewById(R.id.vendor);
resolution = (TextView) findViewById(R.id.resolution);
maximumRange = (TextView) findViewById(R.id.maximumRange);
magneticXTextView = (TextView) findViewById(R.id.magneticX);
magneticYTextView = (TextView) findViewById(R.id.magneticY);
magneticZTextView = (TextView) findViewById(R.id.magneticZ);
mSensorManager.registerListener(this, mAccelerometer, SensorManager.SENSOR_DELAY_FASTEST);
mSensorManager.registerListener(this, mGeomagnetic, SensorManager.SENSOR_DELAY_FASTEST);
}
/**
* Refresh statistics.
*
* @param view - refresh button view.
*/
public void onClickRefreshMagneticButton(View view) {
resetKalmanFilter();
}
/**
* Switch Kalman filtering on/off
*
* @param view - Klaman filetring switcher (checkbox)
*/
public void onClickKalmanFilteringCheckBox(View view) {
CheckBox kalmanFiltering = (CheckBox) view;
this.kalmanFiletring = kalmanFiltering.isChecked();
}
@Override
public void onSensorChanged(SensorEvent sensorEvent) {
if (sensorEvent.accuracy == SensorManager.SENSOR_STATUS_UNRELIABLE) {
return;
}
synchronized (this) {
switch(sensorEvent.sensor.getType()){
case Sensor.TYPE_ACCELEROMETER:
accelerometerValues = sensorEvent.values.clone();
break;
case Sensor.TYPE_MAGNETIC_FIELD:
if (!specDefined) {
vendor.setText("Vendor: " + sensorEvent.sensor.getVendor() + " " + sensorEvent.sensor.getName());
float resolutionValue = sensorEvent.sensor.getResolution() * nanoTtoGRate;
resolution.setText("Resolution: " + resolutionValue);
float maximumRangeValue = sensorEvent.sensor.getMaximumRange() * nanoTtoGRate;
maximumRange.setText("Maximum range: " + maximumRangeValue);
}
geomagneticValues = sensorEvent.values.clone();
break;
}
if (accelerometerValues != null && geomagneticValues != null) {
float[] Rs = new float[16];
float[] I = new float[16];
if (SensorManager.getRotationMatrix(Rs, I, accelerometerValues, geomagneticValues)) {
float[] RsInv = new float[16];
Matrix.invertM(RsInv, 0, Rs, 0);
float resultVec[] = new float[4];
float[] geomagneticValuesAdjusted = new float[4];
geomagneticValuesAdjusted[0] = geomagneticValues[0];
geomagneticValuesAdjusted[1] = geomagneticValues[1];
geomagneticValuesAdjusted[2] = geomagneticValues[2];
geomagneticValuesAdjusted[3] = 0;
Matrix.multiplyMV(resultVec, 0, RsInv, 0, geomagneticValuesAdjusted, 0);
for (int i = 0; i < resultVec.length; i++) {
resultVec[i] = resultVec[i] * nanoTtoGRate * gToCountRate;
}
if (kalmanFiletring) {
KalmanState currentKalmanStateX = new KalmanState(MEASUREMENT_NOISE, accelerometerValues[0], (double)resultVec[0], previousKalmanStateX);
previousKalmanStateX = currentKalmanStateX;
KalmanState currentKalmanStateY = new KalmanState(MEASUREMENT_NOISE, accelerometerValues[1], (double)resultVec[1], previousKalmanStateY);
previousKalmanStateY = currentKalmanStateY;
KalmanState currentKalmanStateZ = new KalmanState(MEASUREMENT_NOISE, accelerometerValues[2], (double)resultVec[2], previousKalmanStateZ);
previousKalmanStateZ = currentKalmanStateZ;
if (previousKalmanStateCounter == KALMAN_STATE_MAX_SIZE) {
magneticXTextView.setText("x: " + previousKalmanStateX.getX_estimate());
magneticYTextView.setText("y: " + previousKalmanStateY.getX_estimate());
magneticZTextView.setText("z: " + previousKalmanStateZ.getX_estimate());
resetKalmanFilter();
} else {
previousKalmanStateCounter++;
}
} else {
magneticXTextView.setText("x: " + resultVec[0]);
magneticYTextView.setText("y: " + resultVec[1]);
magneticZTextView.setText("z: " + resultVec[2]);
}
}
}
}
}
private void resetKalmanFilter() {
previousKalmanStateX = null;
previousKalmanStateY = null;
previousKalmanStateZ = null;
previousKalmanStateCounter = 0;
}
@Override
public void onAccuracyChanged(Sensor sensor, int i) {
}
}
谢谢大家谁读这篇文章，谁张贴有关这个问题的一些想法提前。
