参考文章:https://www.cnblogs.com/zhoug2020/p/7636742.html
MPU6050模块如下图:
该模块测量的是三轴的角速度和角度量,三轴是指Roll、Pitch、Yaw,如下图:
这些信息我们可以用来作为控制无人机的反馈信息,通过控制算法,最终使无人机的姿态(即MPU6050测得的数据)满足我们需要的值,比方说三轴角速度为零,悬停时Roll=0,Pitch=0,Yaw=初始值。
模块与Arduino连线如下:
Andrino读取代码
mpu6050.h
#ifndef _MPU6050_H_
#define _MPU6050_H_
#include <Arduino.h>
#include <Kalman.h>
#include <Wire.h>
#include <Math.h>
extern float fLastRoll;
extern float fRollRate;//单位:°/ms
extern float fLastPitch;
extern float fPitchRate;//单位:°/ms
void mpu6050_dsp(void);//初始化
void mpu6050_read(long dT_us);//读取mpu6050数据
void WriteMPUReg(int nReg, unsigned char nVal);
unsigned char ReadMPUReg(int nReg);
void ReadAccGyr(int *pVals);
void Calibration();
float GetRoll(float *pRealVals, float fNorm);
float GetPitch(float *pRealVals, float fNorm);
float GetYaw(float *pRealVals, float fNorm);
void Rectify(int *pReadout, float *pRealVals);
#endif
mpu6050.cpp
#include <Kalman.h>
#include <Wire.h>
#include <Math.h>
#include <Arduino.h>
#include "mpu6050.h"
float fRad2Deg = 57.295779513f; //将弧度转为角度的乘数
const int MPU = 0x68; //MPU-6050的I2C地址
const int nValCnt = 7; //一次读取寄存器的数量
const int nCalibTimes = 1000; //校准时读数的次数
int calibData[nValCnt]; //校准数据
float fLastRoll = 0.0f; //上一次滤波得到的Roll角
float fLastPitch = 0.0f; //上一次滤波得到的Pitch角
Kalman kalmanRoll; //Roll角滤波器
Kalman kalmanPitch; //Pitch角滤波器
//对Roll角和Pitch角进行卡尔曼滤波
float fNewRoll = 0.0f;
float fNewPitch = 0.0f;
//跟据滤波值计算角度速
float fRollRate = 0.0f;
float fPitchRate = 0.0f;
//————————————————初始化函数————————————————————————————————
void mpu6050_dsp(void)
{
Wire.begin(); //初始化Wire库
WriteMPUReg(0x6B, 0); //启动MPU6050设备 (设置I2C接口,添加一个字节的寄存器变量)
Calibration(); //执行校准
}
//———————————————读取mpu6050数据函数———————————————————————————————
void mpu6050_read(long dT_us)
{
int readouts[nValCnt]; //读出加速度计三个分量、温度和三个角速度计保存的数组
ReadAccGyr(readouts); //读出测量值
float realVals[7]; //消除偏移,转换成物理量
Rectify(readouts, realVals); //根据校准的偏移量进行纠正
//计算加速度向量的模长,均以g为单位
float fNorm = sqrt(realVals[0] * realVals[0] + realVals[1] * realVals[1] + realVals[2] * realVals[2]);
float fRoll = GetRoll(realVals, fNorm); //计算Roll角
if (realVals[1] > 0) {
fRoll = -fRoll;
}
float fPitch = GetPitch(realVals, fNorm); //计算Pitch角
if (realVals[0] < 0) {
fPitch = -fPitch;
}
//Serial.print(dt);Serial.print("\n");
//对Roll角和Pitch角进行卡尔曼滤波
fNewRoll = kalmanRoll.getAngle(fRoll, realVals[4], dT_us/1000000.0f);
fNewPitch = kalmanPitch.getAngle(fPitch, realVals[5], dT_us/1000000.0f);
//跟据滤波值计算角度速
fRollRate = (fNewRoll - fLastRoll)*1000000 / dT_us; //单位:s
fPitchRate = (fNewPitch - fLastPitch)*1000000 / dT_us;//单位:s
//更新Roll角和Pitch角
fLastRoll = fNewRoll;
fLastPitch = fNewPitch;
Serial.print("Roll:");
Serial.print(fNewRoll); Serial.print('(');
Serial.print(fRollRate); Serial.print("),\tPitch:");
Serial.print(fNewPitch); Serial.print('(');
Serial.print(fPitchRate); Serial.print(")\n");
}
//——————————————其他的调用函数—————————————————————————————————
void WriteMPUReg(int nReg, unsigned char nVal) {
Wire.beginTransmission(MPU);
Wire.write(nReg);
Wire.write(nVal);
Wire.endTransmission(true);
}
//从MPU6050读出一个字节的数据
//指定寄存器地址,返回读出的值
unsigned char ReadMPUReg(int nReg) {
Wire.beginTransmission(MPU);
Wire.write(nReg);
Wire.requestFrom(MPU, 1, true);
Wire.endTransmission(true);
return Wire.read();
}
//从MPU6050读出加速度计三个分量、温度和三个角速度计
//保存在指定的数组中
void ReadAccGyr(int *pVals) {
Wire.beginTransmission(MPU);
Wire.write(0x3B);
Wire.requestFrom(MPU, nValCnt * 2, true);
Wire.endTransmission(true);
for (long i = 0; i < nValCnt; ++i) {
pVals[i] = Wire.read() << 8 | Wire.read();
}
}
//对大量读数进行统计,校准平均偏移量
void Calibration()
{
float valSums[7] = {0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0f, 0.0};
//先求和
for (int i = 0; i < nCalibTimes; ++i) {
int mpuVals[nValCnt];
ReadAccGyr(mpuVals);
for (int j = 0; j < nValCnt; ++j) {
valSums[j] += mpuVals[j];
}
}
//再求平均
for (int i = 0; i < nValCnt; ++i) {
calibData[i] =(int)(valSums[i] / nCalibTimes);
}
calibData[2] += 16384; //设芯片Z轴竖直向下,设定静态工作点。
}
//算得Roll角。算法见文档。绕x轴旋转
float GetRoll(float *pRealVals, float fNorm) {
float fNormXZ = sqrt(pRealVals[0] * pRealVals[0] + pRealVals[2] * pRealVals[2]);
float fCos = fNormXZ / fNorm;
return acos(fCos) * fRad2Deg; //fRad2Deg = 57.295779513f; //将弧度转为角度的乘数
}
//算得Pitch角。算法见文档。绕y轴旋转
float GetPitch(float *pRealVals, float fNorm) {
float fNormYZ = sqrt(pRealVals[1] * pRealVals[1] + pRealVals[2] * pRealVals[2]);
float fCos = fNormYZ / fNorm;
return acos(fCos) * fRad2Deg;
}
计算Yaw角。绕z轴旋转,仅变化量
//float GetYaw(float *pRealVals, float fNorm) {
// float fNormYZ = sqrt(pRealVals[1] * pRealVals[1] + pRealVals[2] * pRealVals[2]);
// float fCos = fNormYZ / fNorm;
// return acos(fCos) * fRad2Deg;
//}
//对读数进行纠正,消除偏移,并转换为物理量。公式见文档。
void Rectify(int *pReadout, float *pRealVals) {
for (int i = 0; i < 3; ++i) {
pRealVals[i] = (float)(pReadout[i] - calibData[i]) / 16384.0f;
}
pRealVals[3] = pReadout[3] / 340.0f + 36.53;
for (int i = 4; i < 7; ++i) {
pRealVals[i] = (float)(pReadout[i] - calibData[i]) / 131.0f;
}
}
main.cpp
//测试代码
void setup() {
// put your setup code here, to run once:
Serial.begin(9600); //初始化串口,指定波特率
mpu6050_dsp();
delay(500);
Serial.print("Init OK!\n");
}
void loop() {
// put your main code here, to run repeatedly:
mpu6050_read(1000);
dalay(1);
}
读取性能
经过测试,读取mpu6050所需时间小于1ms。