用Arduino nuo+MPU6050做头追
最近和朋友在玩航模，想玩FPV。就想着搞一个“头追”。上X宝一搜，一般的都要一百多。再上上各种diy论坛发现有各种大神都已经diy出来了。本着自己动手丰衣足食的精神。我也买来板子准备自己做一个。首先说明，如果你不想深入地了解整个原理，可以看其他帖子，按其他帖子来是可以做出来的。这个帖子我希望有更多的大神来给我指导一下，因为我想借做头追，了解一下mpu6050以及卡尔曼滤波。后面呢我还想自己做一个简单的飞控。废话少说。先说一下材料：1：Arduino Uno R3板一块；
2：MPU6050一块
硬件准备好，接下来就要软件了。使用arduino，当然用arduinoIDE了，找度娘很简单就找到了。还有一个看串口波形的软件，我用的Serialchart 挺简单的（我是新手，也只用过那个。。。）
接下来说程序
/* Copyright (C) 2012 Kristian Lauszus, TKJ Electronics. All rights reserved.
This software may be distributed and modified under the terms of the GNU
General Public License version 2 (GPL2) as published by the Free Software
Foundation and appearing in the file GPL2.TXT included in the packaging of
this file. Please note that GPL2 Section 2 requires that all works based
on this software must also be made publicly available under the terms of
the GPL2 ("Copyleft").
Contact information
-------------------
Kristian Lauszus, TKJ Electronics
Web : http://www.tkjelectronics.com
e-mail : [email protected]
*/
#include <Wire.h> //mpu6050和arduino通过I2C通信，所以要包含这个库
#include <Kalman.h> //卡尔曼滤波函数
Kalman kalmanX; // 对X,Y轴创建卡尔曼实例
Kalman kalmanY;
/* IMU Data */
double accX, accY, accZ;
double gyroX, gyroY, gyroZ;//从mpu6050读出的六个数据
double gyroXangle, gyroYangle; // Angle calculate using the gyro only
double compAngleX, compAngleY; // Calculated angle using a complementary filter
double kalAngleX, kalAngleY; // Calculated angle using a Kalman filter
double angleX, angleY, angle, angleZ; //finall angle
uint32_t timer;
uint8_t i2cData; // Buffer for I2C data
// TODO: Make calibration routine
void setup() {
Serial.begin(115200);
Wire.begin();
#if ARDUINO >= 157
Wire.setClock(400000UL); // Set I2C frequency to 400kHz
#else
TWBR = ((F_CPU / 400000UL) - 16) / 2; // Set I2C frequency to 400kHz
#endif
i2cData = 7; // Set the sample rate to 1000Hz - 8kHz/(7+1) = 1000Hz
i2cData = 0x00; // Disable FSYNC and set 260 Hz Acc filtering, 256 Hz Gyro filtering, 8 KHz sampling
i2cData = 0x00; // Set Gyro Full Scale Range to ±250deg/s
i2cData = 0x00; // Set Accelerometer Full Scale Range to ±2g
while (i2cWrite(0x19, i2cData, 4, false)); // Write to all four registers at once
while (i2cWrite(0x6B, 0x01, true)); // PLL with X axis gyroscope reference and disable sleep mode
while (i2cRead(0x75, i2cData, 1));
if (i2cData != 0x68) { // Read "WHO_AM_I" register
Serial.print(F("Error reading sensor"));
while (1);
}
delay(100); // Wait for sensor to stabilize
/* Set kalman and gyro starting angle */
while (i2cRead(0x3B, i2cData, 6));
accX = (i2cData << 8) | i2cData;
accY = (i2cData << 8) | i2cData;
accZ = (i2cData << 8) | i2cData;
// Source: http://www.freescale.com/files/sensors/doc/app_note/AN3461.pdf eq. 25 and eq. 26
// atan2 outputs the value of -π to π (radians) - see http://en.wikipedia.org/wiki/Atan2
// It is then converted from radians to degrees
#ifdef RESTRICT_PITCH // Eq. 25 and 26
double roll = atan2(accY, accZ) * RAD_TO_DEG;
double pitch = atan(-accX / sqrt(accY * accY + accZ * accZ)) * RAD_TO_DEG;
#else // Eq. 28 and 29
double roll = atan(accY / sqrt(accX * accX + accZ * accZ)) * RAD_TO_DEG;
double pitch = atan2(-accX, accZ) * RAD_TO_DEG;
#endif
kalmanX.setAngle(roll); // Set starting angle
kalmanY.setAngle(pitch);
gyroXangle = roll;
gyroYangle = pitch;
compAngleX = roll;
compAngleY = pitch;
//Calibration();
timer = micros();
}
void loop() {
/* Update all the values */
while (i2cRead(0x3B, i2cData, 14));
accX = ((i2cData << 8) | i2cData);
accY = ((i2cData << 8) | i2cData);
accZ = ((i2cData << 8) | i2cData);
//tempRaw = (i2cData << 8) | i2cData;
gyroX = (i2cData << 8) | i2cData;
gyroY = (i2cData << 8) | i2cData;
gyroZ = (i2cData << 8) | i2cData;
double dt = (double)(micros() - timer) / 1000000; // Calculate delta time
timer = micros();
// Source: http://www.freescale.com/files/sensors/doc/app_note/AN3461.pdf eq. 25 and eq. 26
// atan2 outputs the value of -π to π (radians) - see http://en.wikipedia.org/wiki/Atan2
// It is then converted from radians to degrees
#ifdef RESTRICT_PITCH // Eq. 25 and 26
double roll = atan2(accY, accZ) * RAD_TO_DEG;
double pitch = atan(-accX / sqrt(accY * accY + accZ * accZ)) * RAD_TO_DEG;
#else // Eq. 28 and 29
double roll = atan(accY / sqrt(accX * accX + accZ * accZ)) * RAD_TO_DEG;
double pitch = atan2(-accX, accZ) * RAD_TO_DEG;
#endif
double gyroXrate = gyroX / 131.0; // Convert to deg/s
double gyroYrate = gyroY / 131.0; // Convert to deg/s
#ifdef RESTRICT_PITCH
// This fixes the transition problem when the accelerometer angle jumps between -180 and 180 degrees
if ((roll < -90 && kalAngleX > 90) || (roll > 90 && kalAngleX < -90)) {
kalmanX.setAngle(roll);
compAngleX = roll;
kalAngleX = roll;
gyroXangle = roll;
} else
kalAngleX = kalmanX.getAngle(roll, gyroXrate, dt); // Calculate the angle using a Kalman filter
if (abs(kalAngleX) > 90)
gyroYrate = -gyroYrate; // Invert rate, so it fits the restriced accelerometer reading
kalAngleY = kalmanY.getAngle(pitch, gyroYrate, dt);
#else
// This fixes the transition problem when the accelerometer angle jumps between -180 and 180 degrees
if ((pitch < -90 && kalAngleY > 90) || (pitch > 90 && kalAngleY < -90)) {
kalmanY.setAngle(pitch);
compAngleY = pitch;
kalAngleY = pitch;
gyroYangle = pitch;
} else
kalAngleY = kalmanY.getAngle(pitch, gyroYrate, dt); // Calculate the angle using a Kalman filter
if (abs(kalAngleY) > 90)
gyroXrate = -gyroXrate; // Invert rate, so it fits the restriced accelerometer reading
kalAngleX = kalmanX.getAngle(roll, gyroXrate, dt); // Calculate the angle using a Kalman filter
#endif
gyroXangle += gyroXrate * dt; // Calculate gyro angle without any filter
gyroYangle += gyroYrate * dt;
angle += gyroZ * dt / 131.0;
//gyroXangle += kalmanX.getRate() * dt; // Calculate gyro angle using the unbiased rate
//gyroYangle += kalmanY.getRate() * dt;
compAngleX = 0.93 * (compAngleX + gyroXrate * dt) + 0.07 * roll; // Calculate the angle using a Complimentary filter
compAngleY = 0.93 * (compAngleY + gyroYrate * dt) + 0.07 * pitch;
// Reset the gyro angle when it has drifted too much
if (gyroXangle < -180 || gyroXangle > 180)
gyroXangle = kalAngleX;
if (gyroYangle < -180 || gyroYangle > 180)
gyroYangle = kalAngleY;
angleX = kalAngleX - 2.32;
angleY = kalAngleY + 0.38;
angleZ = angle + 5;
/* Print Data */
#if 0 // Set to 1 to activate
Serial.print(accX); Serial.print(",");
Serial.print(accY); Serial.print(",");
Serial.print(accZ); Serial.print(",");
Serial.print(tempRaw); Serial.print(",");
Serial.print(gyroX / 131.0); Serial.print(",");
Serial.print(gyroY / 131.0); Serial.print(",");
Serial.print(gyroZ / 131.0); Serial.print(",");
Serial.print("\t");
#endif
//Serial.print(roll); Serial.print("\t");
//Serial.print(gyroXangle); Serial.print("\t");
//Serial.print(compAngleX); Serial.print("\t");
Serial.print(angleX); Serial.print(",");
//Serial.print("\t");
//Serial.print(pitch); Serial.print("\t");
//Serial.print(gyroYangle); Serial.print("\t");
//Serial.print(compAngleY); Serial.print("\t");
Serial.print(angleY); Serial.print(",");
Serial.print(angleZ); Serial.print(",");
}
以上代码主要部分来自github里kalman函数带的一个例子mpu6050，做了一些细微的改变，毕竟新手嘛。现在呢是可以读出三轴的角度，接下来就是通过遥控器教练通道将数据通过遥控器发给接受器了。这里我还没有弄懂怎么将俩路pwm信号通过教练通道发给遥控器。等了解了再写。第一次接触mpu6050，第一次接触卡尔曼，第一次写帖子。希望大家轻拍。如果有问题，我尽我所知道的给予解答。也希望大神能够指点一二。谢谢。所需的库文件我都放在附件里。
先收藏着，以后试试！ 先收藏，以后试试！
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