Hey everyone I'm trying to create an Arduino module that is connected to an MPU6050 accellerometer + gyroscope sensor and I need for it to digital print (roll/pitch/yaw) for me to simulate it's position using processing.
The code overall works but the data is not reliable, the "yaw" drifts a bit even when the sensor is steady but all of them drift a lot when I move the sensor and then I position it back on a flat surface.
This is the code I'm using:
#include <Wire.h>
const int MPU = 0x68; // MPU6050 I2C address
const int BUTTON_PIN = 4; // To reset and calibrate the accelerometer and gyro with a push button
float AccX, AccY, AccZ;
float GyroX, GyroY, GyroZ;
float accAngleX, accAngleY, gyroAngleX, gyroAngleY, gyroAngleZ;
float roll, pitch, yaw;
float AccErrorX, AccErrorY, GyroErrorX, GyroErrorY, GyroErrorZ;
float elapsedTime, currentTime, previousTime;
int c = 0;
int ledPin = 2; // Define the pin connected to the transistor's base (To activate a 5V laser Light)
// New variables to handle calibration
int buttonState = 0;
int lastButtonState = 0;
bool doCalibration = false;
void setup() {
pinMode(BUTTON_PIN, INPUT);
pinMode(ledPin, OUTPUT);
Serial.begin(19200);
Wire.begin(); // Initialize comunication
Wire.beginTransmission(MPU); // Start communication with MPU6050 // MPU=0x68
Wire.write(0x6B); // Talk to the register 6B
Wire.write(0x00); // Make reset - place a 0 into the 6B register
Wire.endTransmission(true); //end the transmission
/*
// Configure Accelerometer Sensitivity - Full Scale Range (default +/- 2g)
Wire.beginTransmission(MPU);
Wire.write(0x1C); //Talk to the ACCEL_CONFIG register (1C hex)
Wire.write(0x10); //Set the register bits as 00010000 (+/- 8g full scale range)
Wire.endTransmission(true);
// Configure Gyro Sensitivity - Full Scale Range (default +/- 250deg/s)
Wire.beginTransmission(MPU);
Wire.write(0x1B); // Talk to the GYRO_CONFIG register (1B hex)
Wire.write(0x10); // Set the register bits as 00010000 (1000deg/s full scale)
Wire.endTransmission(true);
delay(20);
*/
// Call this function if you need to get the IMU error values for your module
calculate_IMU_error();
delay(20);
}
void loop() {
buttonState = digitalRead(BUTTON_PIN); //I added this code because the accellerometer mesurment were not stable but the aim would be to remove it
if (buttonState == HIGH && lastButtonState == LOW) {
doCalibration = true;
}
lastButtonState = buttonState;
if (doCalibration) {
calculate_IMU_error();
doCalibration = false;
gyroAngleX = gyroAngleY = yaw = 0; // resetting angles when calibrating
}
// === Read acceleromter data === //
digitalWrite(ledPin, HIGH);
Wire.beginTransmission(MPU);
Wire.write(0x3B); // Start with register 0x3B (ACCEL_XOUT_H)
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true); // Read 6 registers total, each axis value is stored in 2 registers
//For a range of +-2g, we need to divide the raw values by 16384, according to the datasheet
AccX = (Wire.read() << 8 | Wire.read()) / 16384.0; // X-axis value
AccY = (Wire.read() << 8 | Wire.read()) / 16384.0; // Y-axis value
AccZ = (Wire.read() << 8 | Wire.read()) / 16384.0; // Z-axis value
// Calculating Roll and Pitch from the accelerometer data
accAngleX = (atan(AccY / sqrt(pow(AccX, 2) + pow(AccZ, 2))) * 180 / PI) + 0.00 ; // AccErrorX ~(0.58) See the calculate_IMU_error()custom function for more details
accAngleY = (atan(-1 * AccX / sqrt(pow(AccY, 2) + pow(AccZ, 2))) * 180 / PI) + 0.00; // AccErrorY ~(-1.58)
// === Read gyroscope data === //
previousTime = currentTime; // Previous time is stored before the actual time read
currentTime = millis(); // Current time actual time read
elapsedTime = (currentTime - previousTime) / 1000; // Divide by 1000 to get seconds
Wire.beginTransmission(MPU);
Wire.write(0x43); // Gyro data first register address 0x43
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true); // Read 4 registers total, each axis value is stored in 2 registers
GyroX = (Wire.read() << 8 | Wire.read()) / 131.0; // For a 250deg/s range we have to divide first the raw value by 131.0, according to the datasheet
GyroY = (Wire.read() << 8 | Wire.read()) / 131.0;
GyroZ = (Wire.read() << 8 | Wire.read()) / 131.0;
// Correct the outputs with the calculated error values
GyroX = GyroX +0.99; // GyroErrorX ~(-0.56)
GyroY = GyroY +0.20; // GyroErrorY ~(2)
GyroZ = GyroZ -0.01; // GyroErrorZ ~ (-0.8)
// Currently the raw values are in degrees per seconds, deg/s, so we need to multiply by sendonds (s) to get the angle in degrees
gyroAngleX = gyroAngleX + GyroX * elapsedTime; // deg/s * s = deg
gyroAngleY = gyroAngleY + GyroY * elapsedTime;
yaw = yaw + GyroZ * elapsedTime;
// Complementary filter - combine acceleromter and gyro angle values
roll = 0.96 * gyroAngleX + 0.04 * accAngleX;
pitch = 0.96 * gyroAngleY + 0.04 * accAngleY;
// Print the values on the serial monitor
Serial.print(roll);
Serial.print("/");
Serial.print(pitch);
Serial.print("/");
Serial.println(yaw);
}
void calculate_IMU_error() {
// We can call this funtion in the setup section to calculate the accelerometer and gyro data error. From here we will get the error values used in the above equations printed on the Serial Monitor.
// Note that we should place the IMU flat in order to get the proper values, so that we then can the correct values
// Read accelerometer values 200 times
while (c < 200) {
Wire.beginTransmission(MPU);
Wire.write(0x3B);
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true);
AccX = (Wire.read() << 8 | Wire.read()) / 16384.0 ;
AccY = (Wire.read() << 8 | Wire.read()) / 16384.0 ;
AccZ = (Wire.read() << 8 | Wire.read()) / 16384.0 ;
// Sum all readings
AccErrorX = AccErrorX + ((atan((AccY) / sqrt(pow((AccX), 2) + pow((AccZ), 2))) * 180 / PI));
AccErrorY = AccErrorY + ((atan(-1 * (AccX) / sqrt(pow((AccY), 2) + pow((AccZ), 2))) * 180 / PI));
c++;
}
//Divide the sum by 200 to get the error value
AccErrorX = AccErrorX / 200;
AccErrorY = AccErrorY / 200;
c = 0;
// Read gyro values 200 times
while (c < 200) {
Wire.beginTransmission(MPU);
Wire.write(0x43);
Wire.endTransmission(false);
Wire.requestFrom(MPU, 6, true);
GyroX = Wire.read() << 8 | Wire.read();
GyroY = Wire.read() << 8 | Wire.read();
GyroZ = Wire.read() << 8 | Wire.read();
// Sum all readings
GyroErrorX = GyroErrorX + (GyroX / 131.0);
GyroErrorY = GyroErrorY + (GyroY / 131.0);
GyroErrorZ = GyroErrorZ + (GyroZ / 131.0);
c++;
}
//Divide the sum by 200 to get the error value
GyroErrorX = GyroErrorX / 200;
GyroErrorY = GyroErrorY / 200;
GyroErrorZ = GyroErrorZ / 200;
// Print the error values on the Serial Monitor
Serial.print("AccErrorX: ");
Serial.println(AccErrorX);
Serial.print("AccErrorY: ");
Serial.println(AccErrorY);
Serial.print("GyroErrorX: ");
Serial.println(GyroErrorX);
Serial.print("GyroErrorY: ");
Serial.println(GyroErrorY);
Serial.print("GyroErrorZ: ");
Serial.println(GyroErrorZ);
}
I added a calibration button so that when I press it all the parameters go back to 0 and I can calibrate it but that only works on a flat surface and I have to do it every few seconds after that it gets messed up again so it's not practical.
I think I could try to use a Kalman filter but I don't know how to include it in my code.