Android P九轴传感器数据读取
相关资料：
https://www.st.com/zh/mems-and-sensors/lsm9ds1.html#tools-software
https://github.com/STMicroelectronics/STMems_Android_Sensor_HAL_IIO
https://www.st.com/content/st_com/zh/products/embedded-software/mems-and-sensors-software/drivers-for-mems/androidhal-iio.html
陀螺仪，Gyroscope，GYRO-Sensor，通过测量自身的旋转状态，判断出设备当前运动状态，是向前、向后、向左还是向右，是加速还是减速。
加速度计，Accelerometer，G-Sensor，重力感应器，可以感知任意方向上的加速度，可以感知受力情况。
磁力计，Magnetic，M-Sensor，测试磁场强度和方向，定位设备的方位，可以测量出东南西北四个方位的夹角。
总之，陀螺仪知道我们转了几个圈，加速度计知道我们向前走了几米，磁力计知道我们的方位。
安卓中通过监听SensorEventListener来获取传感器的数据。
事件类型：
import android.hardware.Sensor;
public static final String STRING_TYPE_TEMPERATURE = "android.sensor.temperature";
public static final int TYPE_ACCELEROMETER = 1; //加速度计
public static final int TYPE_ACCELEROMETER_UNCALIBRATED = 35;
public static final int TYPE_ALL = -1;
public static final int TYPE_AMBIENT_TEMPERATURE = 13;
public static final int TYPE_DEVICE_PRIVATE_BASE = 65536;
public static final int TYPE_GAME_ROTATION_VECTOR = 15;
public static final int TYPE_GEOMAGNETIC_ROTATION_VECTOR = 20;
public static final int TYPE_GRAVITY = 9;
public static final int TYPE_GYROSCOPE = 4; //陀螺仪
public static final int TYPE_GYROSCOPE_UNCALIBRATED = 16;
public static final int TYPE_HEART_BEAT = 31;
public static final int TYPE_HEART_RATE = 21;
public static final int TYPE_LIGHT = 5;
public static final int TYPE_LINEAR_ACCELERATION = 10;
public static final int TYPE_LOW_LATENCY_OFFBODY_DETECT = 34;
public static final int TYPE_MAGNETIC_FIELD = 2; //磁力计
public static final int TYPE_MAGNETIC_FIELD_UNCALIBRATED = 14;
public static final int TYPE_MOTION_DETECT = 30;
注册监听：
sensorManager.registerListener(this,
sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD),
SensorManager.SENSOR_DELAY_NORMAL);
sensorManager.registerListener(this,
sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD_UNCALIBRATED),
SensorManager.SENSOR_DELAY_NORMAL);
sensorManager.registerListener(this,
sensorManager.getDefaultSensor(Sensor.TYPE_GYROSCOPE),
SensorManager.SENSOR_DELAY_NORMAL);
完整代码：
public class MainActivity extends AppCompatActivity implements SensorEventListener{
private static final String TAG = "Magnetometer";
private TextView magnetometer_value;
private TextView accelerometer_value_X;
private TextView accelerometer_value_Y;
private TextView accelerometer_value_Z;
private TextView gyroscope_value_X;
private TextView gyroscope_value_Y;
private TextView gyroscope_value_Z;
private SensorManager sensorManager;
public static DecimalFormat DECIMAL_FORMATTER;
//Accelerometer
float[] accelerometerValues = new float[3];
float[] gravity = new float[3];
float[] linear_acceleration = new float[3];
float[] magneticValues = new float[3];
//Gyroscope
private static final float NS2S = 1.0f / 1000000000.0f;
private final float[] deltaRotationVector = new float[4];
private float timestamp;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.i(TAG,"Magnetometer,onCreate");
magnetometer_value = (TextView) findViewById(R.id.magnetometer_value);
accelerometer_value_X = (TextView) findViewById(R.id.accelerometer_value_X);
accelerometer_value_Y = (TextView) findViewById(R.id.accelerometer_value_Y);
accelerometer_value_Z = (TextView) findViewById(R.id.accelerometer_value_Z);
gyroscope_value_X = (TextView) findViewById(R.id.gyroscope_value_X);
gyroscope_value_Y = (TextView) findViewById(R.id.gyroscope_value_Y);
gyroscope_value_Z = (TextView) findViewById(R.id.gyroscope_value_Z);
// define decimal formatter
DecimalFormatSymbols symbols = new DecimalFormatSymbols(Locale.US);
symbols.setDecimalSeparator('.');
DECIMAL_FORMATTER = new DecimalFormat("#.#", symbols);
sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
if (sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD) != null){
// Success! There's a magnetometer.
Log.i(TAG,"Magnetometer,Success! There's a magnetometer.");
} else {
// Failure! No magnetometer.
Log.i(TAG,"Magnetometer,Failure! No magnetometer.");
}
}
@Override
protected void onResume() {
super.onResume();
Log.i(TAG,"Magnetometer,onResume");
if (sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD) != null){
// Success! There's a magnetometer.
Log.i(TAG,"Magnetometer,Success! There's a magnetometer.");
} else {
// Failure! No magnetometer.
Log.i(TAG,"Magnetometer,Failure! No magnetometer.");
}
sensorManager.registerListener(this,
sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD),
SensorManager.SENSOR_DELAY_NORMAL);
sensorManager.registerListener(this,
sensorManager.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD_UNCALIBRATED),
SensorManager.SENSOR_DELAY_NORMAL);
sensorManager.registerListener(this,
sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
SensorManager.SENSOR_DELAY_NORMAL);
sensorManager.registerListener(this,
sensorManager.getDefaultSensor(Sensor.TYPE_GYROSCOPE),
SensorManager.SENSOR_DELAY_NORMAL);
}
@Override
protected void onPause() {
super.onPause();
sensorManager.unregisterListener(this);
}
@Override
public void onSensorChanged(SensorEvent event) {
//Log.i(TAG,"onSensorChanged,event=" + event);
if ( event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD ) {
Log.i(TAG,"onSensorChanged,TYPE_MAGNETIC_FIELD");
// get values for each axes X,Y,Z
float magX = event.values[0];
float magY = event.values[1];
float magZ = event.values[2];
double magnitude = Math.sqrt((magX * magX) + (magY * magY) + (magZ * magZ));
// set value on the screen
magnetometer_value.setText( DECIMAL_FORMATTER.format(magnitude) + " \u00B5Tesla");
}else if( event.sensor.getType() == Sensor.TYPE_MAGNETIC_FIELD_UNCALIBRATED ){
Log.i(TAG,"onSensorChanged,TYPE_MAGNETIC_FIELD");
}else if( event.sensor.getType() == Sensor.TYPE_ACCELEROMETER ){
//Log.i(TAG,"onSensorChanged,TYPE_ACCELEROMETER");
accelerometerValues = event.values.clone();
// alpha is calculated as t / (t + dT)
// with t, the low-pass filter's time-constant
// and dT, the event delivery rate
final float alpha = 0.8f;
gravity[0] = alpha * gravity[0] + (1 - alpha) * event.values[0];
gravity[1] = alpha * gravity[1] + (1 - alpha) * event.values[1];
gravity[2] = alpha * gravity[2] + (1 - alpha) * event.values[2];
linear_acceleration[0] = event.values[0] - gravity[0];
linear_acceleration[1] = event.values[1] - gravity[1];
linear_acceleration[2] = event.values[2] - gravity[2];
accelerometer_value_X.setText(DECIMAL_FORMATTER.format( accelerometerValues[0]));
accelerometer_value_Y.setText(DECIMAL_FORMATTER.format( accelerometerValues[1]));
accelerometer_value_Z.setText(DECIMAL_FORMATTER.format( accelerometerValues[2]));
}else if( event.sensor.getType() == Sensor.TYPE_GYROSCOPE ){
// This time step's delta rotation to be multiplied by the current rotation
// after computing it from the gyro sample data.
if (timestamp != 0) {
final float dT = (event.timestamp - timestamp) * NS2S;
// Axis of the rotation sample, not normalized yet.
float axisX = event.values[0];
float axisY = event.values[1];
float axisZ = event.values[2];
// Calculate the angular speed of the sample
float omegaMagnitude = (float)Math.sqrt(axisX*axisX + axisY*axisY + axisZ*axisZ);
// Normalize the rotation vector if it's big enough to get the axis
if (omegaMagnitude > EPSILON) {
axisX /= omegaMagnitude;
axisY /= omegaMagnitude;
axisZ /= omegaMagnitude;
}
// Integrate around this axis with the angular speed by the time step
// in order to get a delta rotation from this sample over the time step
// We will convert this axis-angle representation of the delta rotation
// into a quaternion before turning it into the rotation matrix.
float thetaOverTwo = omegaMagnitude * dT / 2.0f;
float sinThetaOverTwo = (float)Math.sin(thetaOverTwo);
float cosThetaOverTwo = (float)Math.cos(thetaOverTwo);
deltaRotationVector[0] = sinThetaOverTwo * axisX;
deltaRotationVector[1] = sinThetaOverTwo * axisY;
deltaRotationVector[2] = sinThetaOverTwo * axisZ;
deltaRotationVector[3] = cosThetaOverTwo;
gyroscope_value_X.setText( DECIMAL_FORMATTER.format( axisX));
gyroscope_value_Y.setText( DECIMAL_FORMATTER.format( axisY));
gyroscope_value_Z.setText( DECIMAL_FORMATTER.format( axisZ));
}
timestamp = event.timestamp;
float[] deltaRotationMatrix = new float[9];
SensorManager.getRotationMatrixFromVector(deltaRotationMatrix, deltaRotationVector);
// User code should concatenate the delta rotation we computed with the current
// rotation in order to get the updated rotation.
// rotationCurrent = rotationCurrent * deltaRotationMatrix;
}
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
Log.i(TAG,"onSensorChanged,sensor=" + sensor);
Log.i(TAG,"onSensorChanged,accuracy=" + accuracy);
}
}