MPU6050 generating strange values when moves vigorously.

Projects General Guidance
1

Hi

This is my first time playing around with a 6DOF sensor. I am looking to determine the angle of the sensor along a single axis.

The below code did the job nicely but I notices that whenever the board is moves erratically/vigorously, it gives me strange angle values. I am not really sure why this is, do all MPU6050's do this, is the sensor faulty or is my code causing the issue?

Any help would be much appreciated!

//Written by Ahmet Burkay KIRNIK
//TR_CapaFenLisesi
//Measure Angle with a MPU-6050(GY-521)

#include<Wire.h>

const int MPU_addr=0x68;
int16_t AcX,AcY,AcZ,Tmp,GyX,GyY,GyZ;

int minVal=265;
int maxVal=402;

double x;
double y;
double z;

boolean standStatus;
int standDuration;

void setup(){
  Wire.begin();
  Wire.beginTransmission(MPU_addr);
  Wire.write(0x6B);
  Wire.write(0);
  Wire.endTransmission(true);
  Serial.begin(9600);

standStatus = false;
}

void loop(){

  Wire.beginTransmission(MPU_addr);
  Wire.write(0x3B);
  Wire.endTransmission(false);
  Wire.requestFrom(MPU_addr,14,true);
  AcX=Wire.read()<<8|Wire.read();
  AcY=Wire.read()<<8|Wire.read();
  AcZ=Wire.read()<<8|Wire.read();
    int xAng = map(AcX,minVal,maxVal,-90,90);
    int yAng = map(AcY,minVal,maxVal,-90,90);
    int zAng = map(AcZ,minVal,maxVal,-90,90);

       x= RAD_TO_DEG * (atan2(-yAng, -zAng)+PI);
       y= RAD_TO_DEG * (atan2(-xAng, -zAng)+PI);
       z= RAD_TO_DEG * (atan2(-yAng, -xAng)+PI);

     //Serial.print("AngleX= ");
     //Serial.println(x);

     //Serial.print("AngleY= ");
     //Serial.print(y);

     //Serial.print("AngleZ= ");
     //Serial.println(z);

     //Serial.println(standStatus);

    /**/
    if (((x > 90) && (x < 220)) && (standStatus == false)){
      Serial.print(x);
      Serial.print(" upside down ");
      standStatus = true;
      Serial.println(standStatus);
     }
     else if (((x < 20) || (x > 300)) && (standStatus == true)){
      Serial.print(x);
      Serial.print(" right way up ");
      standStatus = false;
      Serial.println(standStatus);
     }

     
}
2

Your module is probably fine, but your code isn't. You should be using a complimentary filter instead to find Euler Angles (such as what you want to do).

3

Your code assumes that the only acceleration is due to gravity. it gives you angles based on that assumption. If you change the velocity at all, the sensor you are adding an acceleration and the angles you get will be relative to the sum of gravity and the induced acceleration.

You could measure the magnitude of the acceleration vector and skip trying to measure angles if the magnitude was much different from 1G.

4

Thanks so much for the replies, this clarifies things more for me. Much appreciated!