手機拍照穩定器項目

最近新發現手裏有三個9G 的舵機和之前想做無人機時買的三軸陀螺儀模塊，閒着沒事在家制作一個手機穩定器。

製作手機穩定器的原理無非是：

三軸陀螺儀檢測到X軸方向沿負方向運動，那麼相機相應X軸的舵機就進行相反的方向移動，以抵消晃動。

我的三軸陀螺儀的芯片是L3G4200D；

在網上有些玩家用的是6軸陀螺儀，MPU6050.相應的庫也很健全，但是目前我沒有，只能充分利用手裏的東西。

電路連線如圖所示：

 

相應的三維結構圖如下：

 

採用標準的笛卡爾三維結構，編程也方便，數學模型好建立。

關於L3G4200D陀螺儀，有如下案例：

 

L3G4200D是意法（ST）半導體公司推出的一款MEMS運動傳感器：三軸數字輸出陀螺儀。可選-250~250、-500~500、-2000-2000dps

開發環境：
系統：XP
單板：Arduino Leonardo
平臺：arduino-1.8.12

目標：讀三軸陀螺儀的原始數據，並通過串口顯示

一、硬件介紹

三軸陀螺儀L3G4200D模塊的原理圖如下：

這裏只用到SCL、SDA、VCC_3.3V、GND分別連接到Arduino的對應接口上。Arduino Leonardo上直接標有SDA、SCL連上即可，其它Arduino根據自己的板子連接。

二、編寫測試代碼

現在的arduino版本高，在網上找的例程都編譯通不過，換了個低版本才編譯通過。可以參考這個上面的代碼 https://github.com/pololu/L3G4200D/tree/66f1448d7f6767e12d0fe0c5c50d4e037aedc27c/L3G4200D 找到這兩個文件L3G4200D.cpp   L3G4200D.h，但文件好像不能直接下，代碼都貼在網頁上，直接copy下來。然後還要在arduino-1.0.1-windows\arduino-1.0.1\libraries下新建L3G4200D目錄，將L3G4200D.cpp   L3G4200D.h拷到剛建的L3G4200D，就可以在Android中使用L3G4200D類。

文件L3G4200D.cpp

 

#include <L3G4200D.h>
#include <Wire.h>
#include <math.h>

// Defines ////////////////////////////////////////////////////////////////

// The Arduino two-wire interface uses a 7-bit number for the address, 
// and sets the last bit correctly based on reads and writes
#define GYR_ADDRESS (0xD2 >> 1)

// Public Methods //////////////////////////////////////////////////////////////

// Turns on the L3G4200D's gyro and places it in normal mode.
void L3G4200D::enableDefault(void)
{
	// 0x0F = 0b00001111
	// Normal power mode, all axes enabled
	writeReg(L3G4200D_CTRL_REG1, 0x0F);
}

// Writes a gyro register
void L3G4200D::writeReg(byte reg, byte value)
{
	Wire.beginTransmission(GYR_ADDRESS);
	Wire.write(reg);
	Wire.write(value);
	Wire.endTransmission();
}

// Reads a gyro register
byte L3G4200D::readReg(byte reg)
{
	byte value;

	Wire.beginTransmission(GYR_ADDRESS);
	Wire.write(reg);
	Wire.endTransmission();
	Wire.requestFrom(GYR_ADDRESS, 1);
	value = Wire.read();
	Wire.endTransmission();

	return value;
}

// Reads the 3 gyro channels and stores them in vector g
void L3G4200D::read()
{
	Wire.beginTransmission(GYR_ADDRESS);
	// assert the MSB of the address to get the gyro 
	// to do slave-transmit subaddress updating.
	Wire.write(L3G4200D_OUT_X_L | (1 << 7)); 
	Wire.endTransmission();
	Wire.requestFrom(GYR_ADDRESS, 6);

	while (Wire.available() < 6);

	uint8_t xla = Wire.read();
	uint8_t xha = Wire.read();
	uint8_t yla = Wire.read();
	uint8_t yha = Wire.read();
	uint8_t zla = Wire.read();
	uint8_t zha = Wire.read();

	g.x = xha << 8 | xla;
	g.y = yha << 8 | yla;
	g.z = zha << 8 | zla;
}

void L3G4200D::vector_cross(const vector *a,const vector *b, vector *out)
{
  out->x = a->y*b->z - a->z*b->y;
  out->y = a->z*b->x - a->x*b->z;
  out->z = a->x*b->y - a->y*b->x;
}

float L3G4200D::vector_dot(const vector *a,const vector *b)
{
  return a->x*b->x+a->y*b->y+a->z*b->z;
}

void L3G4200D::vector_normalize(vector *a)
{
  float mag = sqrt(vector_dot(a,a));
  a->x /= mag;
  a->y /= mag;
  a->z /= mag;
}

文件L3G4200D.h：

 

 

#ifndef L3G4200D_h
#define L3G4200D_h

#include <Arduino.h> // for byte data type

// register addresses

#define L3G4200D_WHO_AM_I      0x0F

#define L3G4200D_CTRL_REG1     0x20
#define L3G4200D_CTRL_REG2     0x21
#define L3G4200D_CTRL_REG3     0x22
#define L3G4200D_CTRL_REG4     0x23
#define L3G4200D_CTRL_REG5     0x24
#define L3G4200D_REFERENCE     0x25
#define L3G4200D_OUT_TEMP      0x26
#define L3G4200D_STATUS_REG    0x27

#define L3G4200D_OUT_X_L       0x28
#define L3G4200D_OUT_X_H       0x29
#define L3G4200D_OUT_Y_L       0x2A
#define L3G4200D_OUT_Y_H       0x2B
#define L3G4200D_OUT_Z_L       0x2C
#define L3G4200D_OUT_Z_H       0x2D

#define L3G4200D_FIFO_CTRL_REG 0x2E
#define L3G4200D_FIFO_SRC_REG  0x2F

#define L3G4200D_INT1_CFG      0x30
#define L3G4200D_INT1_SRC      0x31
#define L3G4200D_INT1_THS_XH   0x32
#define L3G4200D_INT1_THS_XL   0x33
#define L3G4200D_INT1_THS_YH   0x34
#define L3G4200D_INT1_THS_YL   0x35
#define L3G4200D_INT1_THS_ZH   0x36
#define L3G4200D_INT1_THS_ZL   0x37
#define L3G4200D_INT1_DURATION 0x38

class L3G4200D
{
	public:
		typedef struct vector
		{
			float x, y, z;
		} vector;

		vector g; // gyro angular velocity readings

		void enableDefault(void);

		void writeReg(byte reg, byte value);
		byte readReg(byte reg);

		void read(void);

		// vector functions
		static void vector_cross(const vector *a, const vector *b, vector *out);
		static float vector_dot(const vector *a,const vector *b);
		static void vector_normalize(vector *a);
};

#endif

文件L3G4200D.ino

 

 

#include <Wire.h>
#include <L3G4200D.h>

L3G4200D gyro;

void setup() {
  Serial.begin(9600);
  Wire.begin();
  gyro.enableDefault();
}

void loop() {
  gyro.read();

  Serial.print("G ");
  Serial.print("X: ");
  Serial.print((int)gyro.g.x);
  Serial.print(" Y: ");
  Serial.print((int)gyro.g.y);
  Serial.print(" Z: ");
  Serial.println((int)gyro.g.z);

  delay(100);
}

三、編譯測試

 

Arduino還是很方便操作的，選擇好單板、參考，直接點上面的“對勾”就開始編譯，編譯沒問題，點“->”箭頭狀的，開始上傳程序，直至上傳進度條完成。

接着打開Tools/Serial Monitor 顯示如下：

這是水平放置的結果，傾斜模塊會看到值變化。

 

最終代碼如下：

/*
  DIY Gimbal - MPU6050 Arduino Tutorial
  by Dejan, www.HowToMechatronics.com
  Code based on the MPU6050_DMP6 example from the i2cdevlib library by Jeff Rowberg:
  https://github.com/jrowberg/i2cdevlib
*/
// I2Cdev and MPU6050 must be installed as libraries, or else the .cpp/.h files
// for both classes must be in the include path of your project
#include "I2Cdev.h"

#include "MPU6050_6Axis_MotionApps20.h"
//#include "MPU6050.h" // not necessary if using MotionApps include file

// Arduino Wire library is required if I2Cdev I2CDEV_ARDUINO_WIRE implementation
// is used in I2Cdev.h
#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
#include "Wire.h"
#endif
#include <Servo.h>
// class default I2C address is 0x68
// specific I2C addresses may be passed as a parameter here
// AD0 low = 0x68 (default for SparkFun breakout and InvenSense evaluation board)
// AD0 high = 0x69
MPU6050 mpu;
//MPU6050 mpu(0x69); // <-- use for AD0 high

// Define the 3 servo motors
Servo servo0;
Servo servo1;
Servo servo2;
float correct;
int j = 0;

#define OUTPUT_READABLE_YAWPITCHROLL

#define INTERRUPT_PIN 2  // use pin 2 on Arduino Uno & most boards

bool blinkState = false;

// MPU control/status vars
bool dmpReady = false;  // set true if DMP init was successful
uint8_t mpuIntStatus;   // holds actual interrupt status byte from MPU
uint8_t devStatus;      // return status after each device operation (0 = success, !0 = error)
uint16_t packetSize;    // expected DMP packet size (default is 42 bytes)
uint16_t fifoCount;     // count of all bytes currently in FIFO
uint8_t fifoBuffer[64]; // FIFO storage buffer

// orientation/motion vars
Quaternion q;           // [w, x, y, z]         quaternion container
VectorInt16 aa;         // [x, y, z]            accel sensor measurements
VectorInt16 aaReal;     // [x, y, z]            gravity-free accel sensor measurements
VectorInt16 aaWorld;    // [x, y, z]            world-frame accel sensor measurements
VectorFloat gravity;    // [x, y, z]            gravity vector
float euler[3];         // [psi, theta, phi]    Euler angle container
float ypr[3];           // [yaw, pitch, roll]   yaw/pitch/roll container and gravity vector

// packet structure for InvenSense teapot demo
uint8_t teapotPacket[14] = { '$', 0x02, 0, 0, 0, 0, 0, 0, 0, 0, 0x00, 0x00, '\r', '\n' };



// ================================================================
// ===               INTERRUPT DETECTION ROUTINE                ===
// ================================================================

volatile bool mpuInterrupt = false;     // indicates whether MPU interrupt pin has gone high
void dmpDataReady() {
  mpuInterrupt = true;
}

// ================================================================
// ===                      INITIAL SETUP                       ===
// ================================================================

void setup() {
  // join I2C bus (I2Cdev library doesn't do this automatically)
#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
  Wire.begin();
  Wire.setClock(400000); // 400kHz I2C clock. Comment this line if having compilation difficulties
#elif I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE
  Fastwire::setup(400, true);
#endif

  // initialize serial communication
  // (115200 chosen because it is required for Teapot Demo output, but it's
  // really up to you depending on your project)
  Serial.begin(38400);
  while (!Serial); // wait for Leonardo enumeration, others continue immediately

  // initialize device
  //Serial.println(F("Initializing I2C devices..."));
  mpu.initialize();
  pinMode(INTERRUPT_PIN, INPUT);
  devStatus = mpu.dmpInitialize();
  // supply your own gyro offsets here, scaled for min sensitivity
  mpu.setXGyroOffset(17);
  mpu.setYGyroOffset(-69);
  mpu.setZGyroOffset(27);
  mpu.setZAccelOffset(1551); // 1688 factory default for my test chip

  // make sure it worked (returns 0 if so)
  if (devStatus == 0) {
    // turn on the DMP, now that it's ready
    // Serial.println(F("Enabling DMP..."));
    mpu.setDMPEnabled(true);

    attachInterrupt(digitalPinToInterrupt(INTERRUPT_PIN), dmpDataReady, RISING);
    mpuIntStatus = mpu.getIntStatus();

    // set our DMP Ready flag so the main loop() function knows it's okay to use it
    //Serial.println(F("DMP ready! Waiting for first interrupt..."));
    dmpReady = true;

    // get expected DMP packet size for later comparison
    packetSize = mpu.dmpGetFIFOPacketSize();
  } else {
    // ERROR!
    // 1 = initial memory load failed
    // 2 = DMP configuration updates failed
    // (if it's going to break, usually the code will be 1)
    // Serial.print(F("DMP Initialization failed (code "));
    //Serial.print(devStatus);
    //Serial.println(F(")"));
  }

  // Define the pins to which the 3 servo motors are connected
  servo0.attach(10);
  servo1.attach(9);
  servo2.attach(8);
}
// ================================================================
// ===                    MAIN PROGRAM LOOP                     ===
// ================================================================

void loop() {
  // if programming failed, don't try to do anything
  if (!dmpReady) return;

  // wait for MPU interrupt or extra packet(s) available
  while (!mpuInterrupt && fifoCount < packetSize) {
    if (mpuInterrupt && fifoCount < packetSize) {
      // try to get out of the infinite loop
      fifoCount = mpu.getFIFOCount();
    }
  }

  // reset interrupt flag and get INT_STATUS byte
  mpuInterrupt = false;
  mpuIntStatus = mpu.getIntStatus();

  // get current FIFO count
  fifoCount = mpu.getFIFOCount();

  // check for overflow (this should never happen unless our code is too inefficient)
  if ((mpuIntStatus & _BV(MPU6050_INTERRUPT_FIFO_OFLOW_BIT)) || fifoCount >= 1024) {
    // reset so we can continue cleanly
    mpu.resetFIFO();
    fifoCount = mpu.getFIFOCount();
    Serial.println(F("FIFO overflow!"));

    // otherwise, check for DMP data ready interrupt (this should happen frequently)
  } else if (mpuIntStatus & _BV(MPU6050_INTERRUPT_DMP_INT_BIT)) {
    // wait for correct available data length, should be a VERY short wait
    while (fifoCount < packetSize) fifoCount = mpu.getFIFOCount();

    // read a packet from FIFO
    mpu.getFIFOBytes(fifoBuffer, packetSize);

    // track FIFO count here in case there is > 1 packet available
    // (this lets us immediately read more without waiting for an interrupt)
    fifoCount -= packetSize;

    // Get Yaw, Pitch and Roll values
#ifdef OUTPUT_READABLE_YAWPITCHROLL
    mpu.dmpGetQuaternion(&q, fifoBuffer);
    mpu.dmpGetGravity(&gravity, &q);
    mpu.dmpGetYawPitchRoll(ypr, &q, &gravity);

    // Yaw, Pitch, Roll values - Radians to degrees
    ypr[0] = ypr[0] * 180 / M_PI;
    ypr[1] = ypr[1] * 180 / M_PI;
    ypr[2] = ypr[2] * 180 / M_PI;
    
    // Skip 300 readings (self-calibration process)
    if (j <= 300) {
      correct = ypr[0]; // Yaw starts at random value, so we capture last value after 300 readings
      j++;
    }
    // After 300 readings
    else {
      ypr[0] = ypr[0] - correct; // Set the Yaw to 0 deg - subtract  the last random Yaw value from the currrent value to make the Yaw 0 degrees
      // Map the values of the MPU6050 sensor from -90 to 90 to values suatable for the servo control from 0 to 180
      int servo0Value = map(ypr[0], -90, 90, 0, 180);
      int servo1Value = map(ypr[1], -90, 90, 0, 180);
      int servo2Value = map(ypr[2], -90, 90, 180, 0);
      
      // Control the servos according to the MPU6050 orientation
      servo0.write(servo0Value);
      servo1.write(servo1Value);
      servo2.write(servo2Value);
    }
#endif
  }
}