Android实现自定义方向盘-3添加平滑处理

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为了使陀螺仪数据更加平滑和稳定，可以通过应用低通滤波器或使用滑动平均法来减少噪声。以下是如何在现有的代码基础上添加平滑处理的详细步骤。

1. 添加低通滤波器

低通滤波器是一种常用的平滑算法，用来过滤掉高频噪声，保留低频信号。我们可以在陀螺仪数据处理中使用低通滤波器来平滑旋转速度。

Step 1: 添加滤波器系数

在GameActivity中添加一个低通滤波器系数。通常，alpha值在0到1之间，越接近1平滑效果越强。

private static final float ALPHA = 0.1f;

Step 2: 应用低通滤波器

在onSensorChanged方法中应用低通滤波器：

private float[] gyroscopeRotationRate = new float[3];@Override
public void onSensorChanged(SensorEvent event) {if (event.sensor.getType() == Sensor.TYPE_GYROSCOPE) {// 低通滤波器：过滤旋转速率gyroscopeRotationRate[0] = lowPassFilter(event.values[0], gyroscopeRotationRate[0]);gyroscopeRotationRate[1] = lowPassFilter(event.values[1], gyroscopeRotationRate[1]);gyroscopeRotationRate[2] = lowPassFilter(event.values[2], gyroscopeRotationRate[2]);float rotationRateZ = gyroscopeRotationRate[2];// 使用过滤后的rotationRateZ更新方向盘角度float newAngle = steeringWheelView.getCurrentAngle() + rotationRateZ * 10;steeringWheelView.updateSteeringWheelAngle(newAngle);}
}private float lowPassFilter(float current, float previous) {return previous + ALPHA * (current - previous);
}

2. 添加滑动平均法

滑动平均法也是一种平滑数据的技术，可以通过记录一定数量的历史数据并计算其平均值来减少噪声。

Step 1: 初始化滑动窗口

在GameActivity中使用一个队列来存储最近的陀螺仪数据：

private static final int WINDOW_SIZE = 10;
private LinkedList<Float> rotationRateZWindow = new LinkedList<>();

Step 2: 计算滑动平均值

在onSensorChanged方法中，将每个新的陀螺仪数据添加到窗口中，并计算滑动平均值：

@Override
public void onSensorChanged(SensorEvent event) {if (event.sensor.getType() == Sensor.TYPE_GYROSCOPE) {float rotationRateZ = event.values[2];// 更新滑动窗口if (rotationRateZWindow.size() >= WINDOW_SIZE) {rotationRateZWindow.poll(); // 移除最早的数据}rotationRateZWindow.add(rotationRateZ);// 计算滑动平均值float averageRotationRateZ = calculateMovingAverage(rotationRateZWindow);// 使用平均值更新方向盘角度float newAngle = steeringWheelView.getCurrentAngle() + averageRotationRateZ * 10;steeringWheelView.updateSteeringWheelAngle(newAngle);}
}private float calculateMovingAverage(LinkedList<Float> window) {float sum = 0;for (float value : window) {sum += value;}return sum / window.size();
}

3. 结合低通滤波器和滑动平均法

你可以同时使用低通滤波器和平滑平均法，以便进一步平滑传感器数据。这将减少数据中的高频噪声，并使其更加稳定。

@Override
public void onSensorChanged(SensorEvent event) {if (event.sensor.getType() == Sensor.TYPE_GYROSCOPE) {// 低通滤波器：过滤旋转速率gyroscopeRotationRate[0] = lowPassFilter(event.values[0], gyroscopeRotationRate[0]);gyroscopeRotationRate[1] = lowPassFilter(event.values[1], gyroscopeRotationRate[1]);gyroscopeRotationRate[2] = lowPassFilter(event.values[2], gyroscopeRotationRate[2]);float rotationRateZ = gyroscopeRotationRate[2];// 更新滑动窗口if (rotationRateZWindow.size() >= WINDOW_SIZE) {rotationRateZWindow.poll();}rotationRateZWindow.add(rotationRateZ);// 计算滑动平均值float averageRotationRateZ = calculateMovingAverage(rotationRateZWindow);// 使用平滑处理后的平均值更新方向盘角度float newAngle = steeringWheelView.getCurrentAngle() + averageRotationRateZ * 10;steeringWheelView.updateSteeringWheelAngle(newAngle);}
}

4. 完整代码

以下是集成了低通滤波器和平滑平均法的完整GameActivity代码：

package com.example.gamecontrol;import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.util.Log;
import androidx.appcompat.app.AppCompatActivity;
import java.util.LinkedList;public class GameActivity extends AppCompatActivity implements SensorEventListener {private static final float ALPHA = 0.1f; // 低通滤波器系数private static final int WINDOW_SIZE = 10; // 滑动窗口大小private SensorManager sensorManager;private Sensor gyroscopeSensor;private SteeringWheelView steeringWheelView;private float[] gyroscopeRotationRate = new float[3];private LinkedList<Float> rotationRateZWindow = new LinkedList<>();@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_game);steeringWheelView = findViewById(R.id.steeringWheelView);sensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);if (sensorManager != null) {gyroscopeSensor = sensorManager.getDefaultSensor(Sensor.TYPE_GYROSCOPE);if (gyroscopeSensor != null) {sensorManager.registerListener(this, gyroscopeSensor, SensorManager.SENSOR_DELAY_GAME);} else {Log.e("GameActivity", "Gyroscope sensor not available.");}}steeringWheelView.setOnSteeringWheelChangeListener(angle -> {Log.d("SteeringWheel", "Angle: " + angle);});}@Overrideprotected void onResume() {super.onResume();if (gyroscopeSensor != null) {sensorManager.registerListener(this, gyroscopeSensor, SensorManager.SENSOR_DELAY_GAME);}}@Overrideprotected void onPause() {super.onPause();sensorManager.unregisterListener(this);}@Overridepublic void onSensorChanged(SensorEvent event) {if (event.sensor.getType() == Sensor.TYPE_GYROSCOPE) {// 低通滤波器gyroscopeRotationRate[0] = lowPassFilter(event.values[0], gyroscopeRotationRate[0]);gyroscopeRotationRate[1] = lowPassFilter(event.values[1], gyroscopeRotationRate[1]);gyroscopeRotationRate[2] = lowPassFilter(event.values[2], gyroscopeRotationRate[2]);float rotationRateZ = gyroscopeRotationRate[2];// 更新滑动窗口if (rotationRateZWindow.size() >= WINDOW_SIZE) {rotationRateZWindow.poll();}rotationRateZWindow.add(rotationRateZ);// 计算滑动平均值float averageRotationRateZ = calculateMovingAverage(rotationRateZWindow);// 更新方向盘角度float newAngle = steeringWheelView.getCurrentAngle() + averageRotationRateZ * 10;steeringWheelView.updateSteeringWheelAngle(newAngle);}}@Overridepublic void onAccuracyChanged(Sensor sensor, int accuracy) {// 不需要处理精度变化}private float lowPassFilter(float current, float previous) {return previous + ALPHA * (current - previous);}private float calculateMovingAverage(LinkedList<Float> window) {float sum = 0;for (float value : window) {sum += value;}return sum / window.size();}
}