Tag Archives: Calibration

In this video lesson we show you how to calibrate the QMC5883L 3-axis magnetometer. The lesson is geared toward this specific magnetometer, but the procedure will be the same for any 3-axis magnetometer. We then use the calibrated reading to measure and calculate the magnetic heading of the device. With this, we have created a calibrated digital compass. In this lesson we are using the GY-87 module, which contains the QMC5883L magnetometer. We are connecting the module to the arduino using the following schematic:

MPU6050 — Schematic for connecting the GY-87 module to the Arduino

In the video we develop two programs. The first program determines your sensor’s calibration constants. Then the second program uses those calibration constants to calculate heading, or yaw. The second program uses the offsets and scale parameters for MY PARTICULAR SENSOR. These values were determined using the first program. You must determine these values for your sensor, and then edit the second program to use your particular calibration parameters.

Program to determine your calibration parameters:

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <QMC5883LCompass.h>
int x, y, z;
int xMax = -10000;
int xMin = 10000;
int yMax = -10000;
int yMin = 10000;
int zMax = -10000;
int zMin = 10000;
float xOffset, xScale, yOffset, yScale, zOffset, zScale;
Adafruit_MPU6050 mpu;
QMC5883LCompass compass;
void setup() {
  Serial.begin(115200);
  mpu.begin();
  mpu.setI2CBypass(true);
  compass.init();
}
void loop() {
  compass.read();
  x = compass.getX();
  y = compass.getY();
  z = compass.getZ();
  if (x > xMax) {
    xMax = x;
  }
  if (x < xMin) {
    xMin = x;
  }
  if (y>yMax){
    yMax=y;
  }
  if (y<yMin){
    yMin=y;
  }
  if (z > zMax) {
    zMax = z;
  }
  if (z < zMin) {
    zMin = z;
  }
  xOffset = (xMax + xMin) / 2.;
  yOffset = (yMax + yMin) / 2.;
  zOffset = (zMax + zMin) / 2.;
  xScale = 2. / (xMax - xMin);
  yScale = 2. / (yMax - yMin);
  zScale = 2. / (zMax - zMin);
  Serial.print(x);
  Serial.print(',');
  Serial.print(y);
  Serial.print(',');
  Serial.print(z);
    Serial.print(',');
  Serial.print(xMax);
  Serial.print(',');
  Serial.print(xMin);
  Serial.print(',');
  Serial.print(yMax);
  Serial.print(',');
  Serial.print(yMin);
  Serial.print(',');
  Serial.print(zMax);
  Serial.print(',');
  Serial.print(zMin);
  Serial.print(',');
  Serial.print(xOffset);
  Serial.print(',');
  Serial.print(yOffset);
  Serial.print(',');
  Serial.print(zOffset);
  Serial.print(',');
  Serial.print(xScale,5);
  Serial.print(',');
  Serial.print(yScale,5);
  Serial.print(',');
  Serial.println(zScale,5);
  delay(100);
}

#include <Adafruit_MPU6050.h>

#include <Adafruit_Sensor.h>

#include <Wire.h>

#include <QMC5883LCompass.h>

int x, y, z;

int xMax = -10000;

int xMin = 10000;

int yMax = -10000;

int yMin = 10000;

int zMax = -10000;

int zMin = 10000;

float xOffset, xScale, yOffset, yScale, zOffset, zScale;

Adafruit_MPU6050 mpu;

QMC5883LCompass compass;

void setup() {

Serial.begin(115200);

mpu.begin();

mpu.setI2CBypass(true);

compass.init();

}

void loop() {

compass.read();

x = compass.getX();

y = compass.getY();

z = compass.getZ();

if (x > xMax) {

xMax = x;

}

if (x < xMin) {

xMin = x;

}

if (y>yMax){

yMax=y;

}

if (y<yMin){

yMin=y;

}

if (z > zMax) {

zMax = z;

}

if (z < zMin) {

zMin = z;

}

xOffset = (xMax + xMin) / 2.;

yOffset = (yMax + yMin) / 2.;

zOffset = (zMax + zMin) / 2.;

xScale = 2. / (xMax - xMin);

yScale = 2. / (yMax - yMin);

zScale = 2. / (zMax - zMin);

Serial.print(x);

Serial.print(',');

Serial.print(y);

Serial.print(',');

Serial.print(z);

Serial.print(',');

Serial.print(xMax);

Serial.print(',');

Serial.print(xMin);

Serial.print(',');

Serial.print(yMax);

Serial.print(',');

Serial.print(yMin);

Serial.print(',');

Serial.print(zMax);

Serial.print(',');

Serial.print(zMin);

Serial.print(',');

Serial.print(xOffset);

Serial.print(',');

Serial.print(yOffset);

Serial.print(',');

Serial.print(zOffset);

Serial.print(',');

Serial.print(xScale,5);

Serial.print(',');

Serial.print(yScale,5);

Serial.print(',');

Serial.println(zScale,5);

delay(100);

}

Once you get your calibration parameters, then put them into this program. This program will then calculate your compass heading:

#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <Wire.h>
#include <QMC5883LCompass.h>
float x,y,z;
//The following numbers are for my particular sensor. You need
//to edit the following lines to put in your sensor calibration
//numbers
float xOffset=-382.5;
float yOffset=378.5;
float zOffset=1014.5;
float xScale = .00121;
float yScale=.00115;
float zScale=.00105;
float head;

Adafruit_MPU6050 mpu;
QMC5883LCompass compass;
void setup() {
Serial.begin(115200);
mpu.begin();
mpu.setI2CBypass(true);
compass.init();
}
void loop() {
 compass.read();
 x = (compass.getX()-xOffset)*xScale;
 y = (compass.getY()-yOffset)*yScale;
 z = (compass.getZ()-zOffset)*zScale;

// Serial.print(x);
// Serial.print(',');
// Serial.print(y);
// Serial.print(',');
// Serial.println(z);
head = atan2(y,x)*360/2/PI;
Serial.print("Heading: ");
Serial.println(head);
 delay(100);
}

#include <Adafruit_MPU6050.h>

#include <Adafruit_Sensor.h>

#include <Wire.h>

#include <QMC5883LCompass.h>

float x,y,z;

//The following numbers are for my particular sensor. You need

//to edit the following lines to put in your sensor calibration

//numbers

float xOffset=-382.5;

float yOffset=378.5;

float zOffset=1014.5;

float xScale = .00121;

float yScale=.00115;

float zScale=.00105;

float head;

Adafruit_MPU6050 mpu;

QMC5883LCompass compass;

void setup() {

Serial.begin(115200);

mpu.begin();

mpu.setI2CBypass(true);

compass.init();

}

void loop() {

compass.read();

x = (compass.getX()-xOffset)*xScale;

y = (compass.getY()-yOffset)*yScale;

z = (compass.getZ()-zOffset)*zScale;

// Serial.print(x);

// Serial.print(',');

// Serial.print(y);

// Serial.print(',');

// Serial.println(z);

head = atan2(y,x)*360/2/PI;

Serial.print("Heading: ");

Serial.println(head);

delay(100);

}

Elegoo Smart Car Tutorial

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

August 6, 2020 admin

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();
}

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

144

145

146

147

148

149

150

151

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();

}

Arduino, Arduino 9-Axis IMU Totorials

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

September 12, 2019 admin

BNO055 IMU — 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

Calibrating a 3-Axis Magnetometer

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!