Project tutorial

Self Balancing Robot using Blubug © GPL3+

Balancing Robot, Balance the robot using wheel and imu 6axis Sensor with BluBug & Android

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Components and supplies

Necessary tools and machines

09507 01
Soldering iron (generic)

About this project

Self Balancing Robot

About

self-balancing, inverted pendulum robot,The build is straightforward and the software is free and open source, based on the Arduino.

The heart of a self-balancing bot is the IMU, consisting of 3-axis rate gyros, accelerometers. These 6 sensors are sampled up to 1,000 times per second and integrated with a piece of code called the DCM (direction-cosine-matrix algorithm), a mathematical filter that combines the best attributes of each sensor. The robot’s higher-level code can simply ask the DCM the angle and the rate of rotation of the bot as needed for balancing.

Circuit Diagram:

We used two dc geared motor & BluBug device,the above circuit diagram show the connection of self balancing robot.

A simple PID loop in the robot’s software is the basis of the balance control:

This works for a while, but the bot constantly accelerates and soon falls over. If the bot tries to right itself, forward motion stops.

Instead we need to move forward while rolling vertically. The first step is to make the wheels rotate at the desired speed while leaving enough power to keep the bot balanced and perfectly upright. Next we take the velocity of the wheels and feed that forward into the desired speed. This gives the bot the ability to resist rapid changes in angle, such as a person trying to push the bot over.

Schematics

Circuit Diagram
Myp1usow5if36tchpcvp

Code

Wheel Balancing RobotArduino
Arduino 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;

#define OUTPUT_READABLE_YAWPITCHROLL

// MPU control/status vars
#define INTERRUPT_PIN 2  // use pin 2 on Arduino Uno & most boards
#define LED_PIN 13 // (Arduino is 13, Teensy is 11, Teensy++ is 6)
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' };

//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;


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

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();
        Wire.setClock(400000); // 400kHz I2C clock. Comment this line if having compilation difficulties
    #elif I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE
        Fastwire::setup(400, true);
    #endif
 
    Serial.begin(115200);
    while (!Serial); // wait for Leonardo enumeration, others continue immediately

    // initialize device
    Serial.println(F("Initializing I2C devices..."));
    mpu.initialize();
    pinMode(INTERRUPT_PIN, INPUT);
    // verify connection
    Serial.println(F("Testing device connections..."));
    Serial.println(mpu.testConnection() ? F("MPU6050 connection successful") : F("MPU6050 connection failed"));

    // wait for ready
    Serial.println(F("\nSend any character to begin DMP programming and demo: "));
    while (Serial.available() && Serial.read()); // empty buffer
    while (!Serial.available());                 // wait for data
    while (Serial.available() && Serial.read()); // empty buffer again


    // 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(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();
        
        //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(")"));
    }
    // configure LED for output
    pinMode(LED_PIN, OUTPUT);
}


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);
         #ifdef OUTPUT_READABLE_YAWPITCHROLL
            // display Euler angles in degrees
            mpu.dmpGetQuaternion(&q, fifoBuffer);
            mpu.dmpGetGravity(&gravity, &q);
            mpu.dmpGetYawPitchRoll(ypr, &q, &gravity);
            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

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