Seesaw_balancing_4WD_robot/Measure_angle_Arduino_MPU6050.ino

#include <Wire.h>
#include <AFMotor.h>
//Declaring some global variables
int gyro_x, gyro_y, gyro_z = 0;
long gyro_x_cal, gyro_y_cal, gyro_z_cal = 0.0;
boolean set_gyro_angles;

long acc_x, acc_y, acc_z, acc_total_vector = 0.0;
float angle_roll_acc, angle_pitch_acc = 0.0;

float angle_pitch, angle_roll = 0.0;
int angle_pitch_buffer, angle_roll_buffer = 0;
float angle_pitch_output, angle_roll_output = 0.0;

long loop_timer = 0.0;
int temp = 0;
AF_DCMotor motor1(1);
AF_DCMotor motor2(2);
AF_DCMotor motor3(3);
AF_DCMotor motor4(4);



void setup() {
  Wire.begin();                                                        //Start I2C as master
  setup_mpu_6050_registers();                                          //Setup the registers of the MPU-6050
  for (int cal_int = 0; cal_int < 1000 ; cal_int ++) {                 //Read the raw acc and gyro data from the MPU-6050 for 1000 times
    read_mpu_6050_data();
    gyro_x_cal += gyro_x;                                              //Add the gyro x offset to the gyro_x_cal variable
    gyro_y_cal += gyro_y;                                              //Add the gyro y offset to the gyro_y_cal variable
    gyro_z_cal += gyro_z;                                              //Add the gyro z offset to the gyro_z_cal variable
    delay(3);                                                          //Delay 3us to have 250Hz for-loop

    motor1.setSpeed(200);
    motor2.setSpeed(200);
    motor3.setSpeed(200);
    motor4.setSpeed(200);
  }

  // divide by 1000 to get avarage offset
  gyro_x_cal /= 1000;
  gyro_y_cal /= 1000;
  gyro_z_cal /= 1000;
  Serial.begin(9600);
  loop_timer = micros();                                               //Reset the loop timer
}

void loop() {

  read_mpu_6050_data();
  //Subtract the offset values from the raw gyro values
  gyro_x -= gyro_x_cal;
  gyro_y -= gyro_y_cal;
  gyro_z -= gyro_z_cal;

  //Gyro angle calculations . Note 0.0000611 = 1 / (250Hz x 65.5)
  angle_pitch += gyro_x * 0.0000611;                                   //Calculate the traveled pitch angle and add this to the angle_pitch variable
  angle_roll += gyro_y * 0.0000611;                                    //Calculate the traveled roll angle and add this to the angle_roll variable
  //0.000001066 = 0.0000611 * (3.142(PI) / 180degr) The Arduino sin function is in radians
  angle_pitch += angle_roll * sin(gyro_z * 0.000001066);               //If the IMU has yawed transfer the roll angle to the pitch angel
  angle_roll -= angle_pitch * sin(gyro_z * 0.000001066);               //If the IMU has yawed transfer the pitch angle to the roll angel

  //Accelerometer angle calculations
  acc_total_vector = sqrt((acc_x * acc_x) + (acc_y * acc_y) + (acc_z * acc_z)); //Calculate the total accelerometer vector
  //57.296 = 1 / (3.142 / 180) The Arduino asin function is in radians
  angle_pitch_acc = asin((float)acc_y / acc_total_vector) * 57.296;    //Calculate the pitch angle
  angle_roll_acc = asin((float)acc_x / acc_total_vector) * -57.296;    //Calculate the roll angle

  angle_pitch_acc -= 0.0;                                              //Accelerometer calibration value for pitch
  angle_roll_acc -= 0.0;                                               //Accelerometer calibration value for roll

  if (set_gyro_angles) {                                               //If the IMU is already started
    angle_pitch = angle_pitch *  0.9996 + angle_pitch_acc * 0.0004;     //Correct the drift of the gyro pitch angle with the accelerometer pitch angle
    angle_roll = angle_roll *  0.9996 + angle_roll_acc * 0.0004;        //Correct the drift of the gyro roll angle with the accelerometer roll angle
  }
  else {                                                               //At first start
    angle_pitch = angle_pitch_acc;                                     //Set the gyro pitch angle equal to the accelerometer pitch angle
    angle_roll = angle_roll_acc;                                       //Set the gyro roll angle equal to the accelerometer roll angle
    set_gyro_angles = true;                                            //Set the IMU started flag
  }

  //To dampen the pitch and roll angles a complementary filter is used
  angle_pitch_output = angle_pitch_output * 0.9 + angle_pitch_acc * 0.1;   //Take 90% of the output pitch value and add 10% of the raw pitch value
  angle_roll_output = angle_roll_output *  0.9 + angle_roll_acc * 0.1;      //Take 90% of the output roll value and add 10% of the raw roll value
  Serial.print(" | Angle  = "); Serial.println(angle_pitch_output);



  while (micros() - loop_timer < 10);
  {//Wait until the loop_timer reaches 4000us (250Hz) before starting the next loop
  loop_timer = micros();//Reset the loop timer
  }
  if (angle_pitch_output > 3)
  {
    motor1.run(FORWARD);
    motor2.run(FORWARD);
    motor3.run(FORWARD);
    motor4.run(FORWARD);
    
  }
  else if (angle_pitch_output < -3)
  {
    motor1.run(BACKWARD);
    motor2.run(BACKWARD);
    motor3.run(BACKWARD);
    motor4.run(BACKWARD);
    
  }
  else if (angle_pitch_output >= -3 || angle_pitch_output <= 3)
  {
    motor1.run(RELEASE);
    motor2.run(RELEASE);
    motor3.run(RELEASE);
    motor4.run(RELEASE);
    
  }
}




void setup_mpu_6050_registers() {
  //Activate the MPU-6050
  Wire.beginTransmission(0x68);                                        //Start communicating with the MPU-6050
  Wire.write(0x6B);                                                    //Send the requested starting register
  Wire.write(0x00);                                                    //Set the requested starting register
  Wire.endTransmission();
  //Configure the accelerometer (+/-8g)
  Wire.beginTransmission(0x68);                                        //Start communicating with the MPU-6050
  Wire.write(0x1C);                                                    //Send the requested starting register
  Wire.write(0x10);                                                    //Set the requested starting register
  Wire.endTransmission();
  //Configure the gyro (500dps full scale)
  Wire.beginTransmission(0x68);                                        //Start communicating with the MPU-6050
  Wire.write(0x1B);                                                    //Send the requested starting register
  Wire.write(0x08);                                                    //Set the requested starting register
  Wire.endTransmission();
}


void read_mpu_6050_data() {                                            //Subroutine for reading the raw gyro and accelerometer data
  Wire.beginTransmission(0x68);                                        //Start communicating with the MPU-6050
  Wire.write(0x3B);                                                    //Send the requested starting register
  Wire.endTransmission();                                              //End the transmission
  Wire.requestFrom(0x68, 14);                                          //Request 14 bytes from the MPU-6050
  while (Wire.available() < 14);                                       //Wait until all the bytes are received
  acc_x = Wire.read() << 8 | Wire.read();
  acc_y = Wire.read() << 8 | Wire.read();
  acc_z = Wire.read() << 8 | Wire.read();
  temp = Wire.read() << 8 | Wire.read();
  gyro_x = Wire.read() << 8 | Wire.read();
  gyro_y = Wire.read() << 8 | Wire.read();
  gyro_z = Wire.read() << 8 | Wire.read();
}