Calibration | Technology Tutorials

Guys in this lesson we show how you can use linear regression to more accurately calibrate turns for our robot car. We will take you through the math step-by-step, and then show how to code up the results. If you want to play along at home, you can get your Elegoo Robot Car HERE.

For your convenience, the code we developed in the lesson is included below.

int ENA=5;
int ENB=6;
int IN1=7;
int IN2=8;
int IN3=9;
int IN4=11;
float d;
int degRot;
int left;
int right;
float v;
void setup() {
  // put your setup code here, to run once:
Serial.begin(9600);
pinMode(ENA,OUTPUT);
pinMode(ENB,OUTPUT);
pinMode(IN1,OUTPUT);
pinMode(IN2,OUTPUT);
pinMode(IN3,OUTPUT);
pinMode(IN4,OUTPUT);
digitalWrite(ENA,HIGH);
digitalWrite(ENB,HIGH);
}

void loop() {
int wv;
v=1.2;
wv=(v-.35)/.0075;
left=wv;
right=wv;
setSpeed(left,right);
forward(5, v);
turnRight(180, wv);
forward(5, v);
//calR(wv);
//forward(8,v);
//v=1.5;
//wv=(v-.35)/.0075;
//left=wv;
//right=wv;
//setSpeed(left,right);
//backward(8,v);
  while(1==1){

  }
}
void setSpeed(int leftVal,int rightVal){
  analogWrite(ENA,leftVal);
  analogWrite(ENB,rightVal);
}
void forward(float d, float v){
float t;
digitalWrite(IN1,HIGH);
digitalWrite(IN2,LOW);
digitalWrite(IN3,LOW);
digitalWrite(IN4,HIGH);
t=d/v*1000;
delay(t);
stopCar();
}
void backward(float d, float v){
float t;
digitalWrite(IN1,LOW);
digitalWrite(IN2,HIGH);
digitalWrite(IN3,HIGH);
digitalWrite(IN4,LOW);
t=d/v*1000;
delay(t);
stopCar();
}
void turnRight(int deg, int wv){
  float t;
stopCar();
delay(100);
analogWrite(ENA,125);
analogWrite(ENB,125);
digitalWrite(IN1,HIGH);
digitalWrite(IN2,LOW);
digitalWrite(IN3,HIGH);
digitalWrite(IN4,LOW);
t=(deg+6)/136.29*1000.;
Serial.println(deg);
delay(t);
stopCar();
analogWrite(ENA,wv);
analogWrite(ENB,wv);
}
void turnLeft(int deg, int wv){
float t;
analogWrite(ENA,125);
analogWrite(ENB,125);
digitalWrite(IN1,LOW);
digitalWrite(IN2,HIGH);
digitalWrite(IN3,LOW);
digitalWrite(IN4,HIGH);
t=(deg+6)/136.29*1000.;
Serial.println(deg);
Serial.println(deg);
delay(t);
stopCar();
analogWrite(ENA,wv);
analogWrite(ENB,wv);
}
void stopCar(){
digitalWrite(IN1,LOW);
digitalWrite(IN2,LOW);
digitalWrite(IN3,LOW);
digitalWrite(IN4,LOW);
}

void calF(){
digitalWrite(IN1,HIGH);
digitalWrite(IN2,LOW);
digitalWrite(IN3,LOW);
digitalWrite(IN4,HIGH);
delay(5000);
stopCar();
}
void calB(){
digitalWrite(IN1,LOW);
digitalWrite(IN2,HIGH);
digitalWrite(IN3,HIGH);
digitalWrite(IN4,LOW);
delay(5000);
stopCar();
}
void calR(int wv){
stopCar();
analogWrite(ENA,125);
analogWrite(ENB,125);
digitalWrite(IN1,HIGH);
digitalWrite(IN2,LOW);
digitalWrite(IN3,HIGH);
digitalWrite(IN4,LOW);
delay(3000);
analogWrite(ENA,wv);
analogWrite(ENB,wv);
stopCar();
}
void calL(int wv){
analogWrite(ENA,125);
analogWrite(ENB,125);
digitalWrite(IN1,LOW);
digitalWrite(IN2,HIGH);
digitalWrite(IN3,LOW);
digitalWrite(IN4,HIGH);
delay(5000);
analogWrite(ENA,wv);
analogWrite(ENB,wv);
stopCar();
}

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int ENA=5;

int ENB=6;

int IN1=7;

int IN2=8;

int IN3=9;

int IN4=11;

float d;

int degRot;

int left;

int right;

float v;

void setup() {

// put your setup code here, to run once:

Serial.begin(9600);

pinMode(ENA,OUTPUT);

pinMode(ENB,OUTPUT);

pinMode(IN1,OUTPUT);

pinMode(IN2,OUTPUT);

pinMode(IN3,OUTPUT);

pinMode(IN4,OUTPUT);

digitalWrite(ENA,HIGH);

digitalWrite(ENB,HIGH);

}

void loop() {

int wv;

v=1.2;

wv=(v-.35)/.0075;

left=wv;

right=wv;

setSpeed(left,right);

forward(5, v);

turnRight(180, wv);

forward(5, v);

//calR(wv);

//forward(8,v);

//v=1.5;

//wv=(v-.35)/.0075;

//left=wv;

//right=wv;

//setSpeed(left,right);

//backward(8,v);

while(1==1){

}

void setSpeed(int leftVal,int rightVal){

analogWrite(ENA,leftVal);

analogWrite(ENB,rightVal);

}

void forward(float d, float v){

float t;

digitalWrite(IN1,HIGH);

digitalWrite(IN2,LOW);

digitalWrite(IN3,LOW);

digitalWrite(IN4,HIGH);

t=d/v*1000;

delay(t);

stopCar();

}

void backward(float d, float v){

float t;

digitalWrite(IN1,LOW);

digitalWrite(IN2,HIGH);

digitalWrite(IN3,HIGH);

digitalWrite(IN4,LOW);

t=d/v*1000;

delay(t);

stopCar();

}

void turnRight(int deg, int wv){

float t;

stopCar();

delay(100);

analogWrite(ENA,125);

analogWrite(ENB,125);

digitalWrite(IN1,HIGH);

digitalWrite(IN2,LOW);

digitalWrite(IN3,HIGH);

digitalWrite(IN4,LOW);

t=(deg+6)/136.29*1000.;

Serial.println(deg);

delay(t);

stopCar();

analogWrite(ENA,wv);

analogWrite(ENB,wv);

}

void turnLeft(int deg, int wv){

float t;

analogWrite(ENA,125);

analogWrite(ENB,125);

digitalWrite(IN1,LOW);

digitalWrite(IN2,HIGH);

digitalWrite(IN3,LOW);

digitalWrite(IN4,HIGH);

t=(deg+6)/136.29*1000.;

Serial.println(deg);

delay(t);

stopCar();

analogWrite(ENA,wv);

analogWrite(ENB,wv);

}

void stopCar(){

digitalWrite(IN1,LOW);

digitalWrite(IN2,LOW);

digitalWrite(IN3,LOW);

digitalWrite(IN4,LOW);

}

void calF(){

digitalWrite(IN1,HIGH);

digitalWrite(IN2,LOW);

digitalWrite(IN3,LOW);

digitalWrite(IN4,HIGH);

delay(5000);

stopCar();

}

void calB(){

digitalWrite(IN1,LOW);

digitalWrite(IN2,HIGH);

digitalWrite(IN3,HIGH);

digitalWrite(IN4,LOW);

delay(5000);

stopCar();

}

void calR(int wv){

stopCar();

analogWrite(ENA,125);

analogWrite(ENB,125);

digitalWrite(IN1,HIGH);

digitalWrite(IN2,LOW);

digitalWrite(IN3,HIGH);

digitalWrite(IN4,LOW);

delay(3000);

analogWrite(ENA,wv);

analogWrite(ENB,wv);

stopCar();

}

void calL(int wv){

analogWrite(ENA,125);

analogWrite(ENB,125);

digitalWrite(IN1,LOW);

digitalWrite(IN2,HIGH);

digitalWrite(IN3,LOW);

digitalWrite(IN4,HIGH);

delay(5000);

analogWrite(ENA,wv);

analogWrite(ENB,wv);

stopCar();

}

Our 9-axis BNO055 9-axis sensor connected to our Aurduino Nano

In this lesson we show you how to get a clean calibration on your BNO055 9-axis sensor. In the video below we take you through the coded needed to calibrate the sensor, and a simple technique to quickly get the system properly calibrated.

The code developed in this video will be used in future lessons, and is included below:

The code below is for demo purposes only, and should not be used in any real applications. It just demonstrates how to work with this sensor in benchtop presentations.

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_BNO055.h>
#include <utility/imumaths.h>

#define BNO055_SAMPLERATE_DELAY_MS (100)

Adafruit_BNO055 myIMU = Adafruit_BNO055();

void setup() {
  // put your setup code here, to run once:
Serial.begin(115200);
myIMU.begin();
delay(1000);
int8_t temp=myIMU.getTemp();
myIMU.setExtCrystalUse(true);
}

void loop() {
  // put your main code here, to run repeatedly:
uint8_t system, gyro, accel, mg = 0;
myIMU.getCalibration(&system, &gyro, &accel, &mg);
imu::Vector<3> acc =myIMU.getVector(Adafruit_BNO055::VECTOR_ACCELEROMETER);


Serial.print(acc.x());
Serial.print(",");
Serial.print(acc.y());
Serial.print(",");
Serial.print(acc.z());
Serial.print(",");
Serial.print(accel);
Serial.print(",");
Serial.print(gyro);
Serial.print(",");
Serial.print(mg);
Serial.print(",");
Serial.println(system);

 
delay(BNO055_SAMPLERATE_DELAY_MS);
}

#include <Wire.h>

#include <Adafruit_Sensor.h>

#include <Adafruit_BNO055.h>

#include <utility/imumaths.h>

#define BNO055_SAMPLERATE_DELAY_MS (100)

Adafruit_BNO055 myIMU = Adafruit_BNO055();

void setup() {

// put your setup code here, to run once:

Serial.begin(115200);

myIMU.begin();

delay(1000);

int8_t temp=myIMU.getTemp();

myIMU.setExtCrystalUse(true);

}

void loop() {

// put your main code here, to run repeatedly:

uint8_t system, gyro, accel, mg = 0;

myIMU.getCalibration(&system, &gyro, &accel, &mg);

imu::Vector<3> acc =myIMU.getVector(Adafruit_BNO055::VECTOR_ACCELEROMETER);

Serial.print(acc.x());

Serial.print(",");

Serial.print(acc.y());

Serial.print(",");

Serial.print(acc.z());

Serial.print(",");

Serial.print(accel);

Serial.print(",");

Serial.print(gyro);

Serial.print(",");

Serial.print(mg);

Serial.print(",");

Serial.println(system);

delay(BNO055_SAMPLERATE_DELAY_MS);

}

Technology Tutorials

Tag Archives: Calibration

Robotics Training LESSON 9: Calibrate Robot Car Turn Angles with Linear Regression

9-Axis IMU LESSON 5: Calibrating the BNO055 9-axis Inertial Measurement Sensor

Making The World a Better Place One High Tech Project at a Time. Enjoy!