Self Balancing Robot Using Arduino

Self Balancing Robot

My latest Arduino DIY project is a self balancing robot.

Arduino Uno R3 microcontroller board is used for this project. MPU6050, an 6DOF IMU (with accelerometer and gyroscope) is used to get the angle and L298N motor controller board controls the 2 motors. The motors are 12V 500rpm and the wheels are 8cm in diameter. Robot size is 17x10x30 cm. Three plexiglas plates are used to hold the frame and parts. Standard PID controller is used to control the robot. To tune the PID controller parameters 3 No, 10k potentiometers are used.

You may find the Arduino sketch and libs on GitHub.

First you download this zip file and then un-zip it. you will get main code and libraries.

Separate each libraries and zip it and add to Arduino  IDE Library.

 https://github.com/lukagabric/Franko

Parts:1 x Arduino Uno R3
1 x MPU6050 (IMU)
1 x L298N Motor Driver Controller
2 x 12V 500 RPM Gear Motors + 80mm Wheels
3 x 10k Potentiometer

Connection Diagram

For Manuel PID setting. 

PID vale selection by potentiometers. 

Code

#include <PID_v1.h>

#include <LMotorController.h>

#include "I2Cdev.h"

#include "MPU6050_6Axis_MotionApps20.h"

#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE

    #include "Wire.h"

#endif

#define LOG_INPUT 0

#define MANUAL_TUNING 0

#define LOG_PID_CONSTANTS 0 //MANUAL_TUNING must be 1

#define MOVE_BACK_FORTH 0

#define MIN_ABS_SPEED 30

//MPU

MPU6050 mpu;

// 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

VectorFloat gravity;    // [x, y, z]            gravity vector

float ypr[3];           // [yaw, pitch, roll]   yaw/pitch/roll container and gravity vector

//PID

#if MANUAL_TUNING

  double kp , ki, kd;

  double prevKp, prevKi, prevKd;

#endif

double originalSetpoint = 174.29;

double setpoint = originalSetpoint;

double movingAngleOffset = 0.3;

double input, output;

int moveState=0; //0 = balance; 1 = back; 2 = forth

#if MANUAL_TUNING

  PID pid(&input, &output, &setpoint, 0, 0, 0, DIRECT);

#else

  PID pid(&input, &output, &setpoint, 70, 240, 1.9, DIRECT);

#endif

//MOTOR CONTROLLER

int ENA = 3;

int IN1 = 4;

int IN2 = 8;

int IN3 = 5;

int IN4 = 7;

int ENB = 6;

LMotorController motorController(ENA, IN1, IN2, ENB, IN3, IN4, 0.6, 1);

//timers

long time1Hz = 0;

long time5Hz = 0;

volatile bool mpuInterrupt = false;     // indicates whether MPU interrupt pin has gone high

void dmpDataReady()

{

    mpuInterrupt = true;

}

void setup()

{

    // join I2C bus (I2Cdev library doesn't do this automatically)

    #if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE

        Wire.begin();

        TWBR = 24; // 400kHz I2C clock (200kHz if CPU is 8MHz)

    #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(115200);

    while (!Serial); // wait for Leonardo enumeration, others continue immediately

    // initialize device

    Serial.println(F("Initializing I2C devices..."));

    mpu.initialize();

    // verify connection

    Serial.println(F("Testing device connections..."));

    Serial.println(mpu.testConnection() ? F("MPU6050 connection successful") : F("MPU6050 connection failed"));

    // load and configure the DMP

    Serial.println(F("Initializing DMP..."));

    devStatus = mpu.dmpInitialize();

    // supply your own gyro offsets here, scaled for min sensitivity

    mpu.setXGyroOffset(220);

    mpu.setYGyroOffset(76);

    mpu.setZGyroOffset(-85);

    mpu.setZAccelOffset(1788); // 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);

        // enable Arduino interrupt detection

        Serial.println(F("Enabling interrupt detection (Arduino external interrupt 0)..."));

        attachInterrupt(0, 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();

        

        //setup PID

        

        pid.SetMode(AUTOMATIC);

        pid.SetSampleTime(10);

        pid.SetOutputLimits(-255, 255);  

    }

    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(")"));

    }

}

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)

    {

        //no mpu data - performing PID calculations and output to motors

        

        pid.Compute();

        motorController.move(output, MIN_ABS_SPEED);

        

        unsigned long currentMillis = millis();

        if (currentMillis - time1Hz >= 1000)

        {

            loopAt1Hz();

            time1Hz = currentMillis;

        }

        

        if (currentMillis - time5Hz >= 5000)

        {

            loopAt5Hz();

            time5Hz = currentMillis;

        }

    }

    // 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 & 0x10) || fifoCount == 1024)

    {

        // reset so we can continue cleanly

        mpu.resetFIFO();

        Serial.println(F("FIFO overflow!"));

    // otherwise, check for DMP data ready interrupt (this should happen frequently)

    }

    else if (mpuIntStatus & 0x02)

    {

        // 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;

        mpu.dmpGetQuaternion(&q, fifoBuffer);

        mpu.dmpGetGravity(&gravity, &q);

        mpu.dmpGetYawPitchRoll(ypr, &q, &gravity);

        #if LOG_INPUT

            Serial.print("ypr\t");

            Serial.print(ypr[0] * 180/M_PI);

            Serial.print("\t");

            Serial.print(ypr[1] * 180/M_PI);

            Serial.print("\t");

            Serial.println(ypr[2] * 180/M_PI);

        #endif

        input = ypr[1] * 180/M_PI + 180;

   }

}

void loopAt1Hz()

{

#if MANUAL_TUNING

    setPIDTuningValues();

#endif

}

void loopAt5Hz()

{

    #if MOVE_BACK_FORTH

        moveBackForth();

    #endif

}

//move back and forth

void moveBackForth()

{

    moveState++;

    if (moveState > 2) moveState = 0;

    

    if (moveState == 0)

      setpoint = originalSetpoint;

    else if (moveState == 1)

      setpoint = originalSetpoint - movingAngleOffset;

    else

      setpoint = originalSetpoint + movingAngleOffset;

}

//PID Tuning (3 potentiometers)

#if MANUAL_TUNING

void setPIDTuningValues()

{

    readPIDTuningValues();

    

    if (kp != prevKp || ki != prevKi || kd != prevKd)

    {

#if LOG_PID_CONSTANTS

        Serial.print(kp);Serial.print(", ");Serial.print(ki);Serial.print(", ");Serial.println(kd);

#endif

        pid.SetTunings(kp, ki, kd);

        prevKp = kp; prevKi = ki; prevKd = kd;

    }

}

void readPIDTuningValues()

{

    int potKp = analogRead(A0);

    int potKi = analogRead(A1);

    int potKd = analogRead(A2);

        

    kp = map(potKp, 0, 1023, 0, 25000) / 100.0; //0 - 250

    ki = map(potKi, 0, 1023, 0, 100000) / 100.0; //0 - 1000

    kd = map(potKd, 0, 1023, 0, 500) / 100.0; //0 - 5

}

#endif