Float and float to a binary operator error

Projects Programming
1

Hello, I am writing a code to do the inverse kinematics for a 3DOF robot. While writing this code I encountered the following error:

Arduino: 1.6.1 (Windows 7), Board: "Arduino Uno"
EXP06_Stocks.ino: In function 'void loop()':
EXP06_Stocks.ino:70:28: error: invalid operands of types 'float' and 'float' to binary 'operator^'
Error compiling.

This error only effects the xt, and yt within my void loop (in my code below). I am using the map() function to draw a straight line along the y axis while maintaining a constant spatial angle.

I'm hoping this will also resolve the issue with my theta values being incorrect.
Any help with understanding the source of this error would be appreciated.

#include <Servo.h>  // adds the Servo.h library commands (allows us to use those commands)

//Servo1
    Servo servo1;  // create servo object to control a servo (named servo1)
               // a maximum of eight servo objects can be created  
    int pos1 = 1465.5;   // variable to store the servo1 position as an integer (midpoint default)
    float ang1 = 0;  // angle of servo1 in degrees (+90 to -90).  Use the 'float' type for decimal #'s

//Servo2
    Servo servo2;  //create servo2
    int pos2=1450;
    float ang2 = 0;  //angle of servo2 in degrees(+90 to -90)

//Servo3
    Servo servo3;    //create servo3
    int pos3=1450;  
    float ang3 = 0;  //angle of servo3 in degrees (+90 to -90)

unsigned int time = 0;    // sets the time variable as an interger and assigns an initial value

void setup()    // this section of code is performed once at startup
{ 
  Serial.begin(9600);         //(115200 is the baud (data transfer) rate.  Start with 9600.
  
//Servo1
    servo1.attach(9, 544, 2400);  // attaches the servo on pin 9 and sets pulse limits
    servo1.writeMicroseconds(1465.5); // starting position (midpoint)

//Servo2
    servo2.attach(10,500,2400);    // attaches the servo to pin 10
    servo2.writeMicroseconds(1450);// Initial position (midpoint)
    
//Servo3
    servo3.attach(11,500,2400);    //attaches the servo to pin 11
    servo3.writeMicroseconds(1450);//Initisal position (midpoint)
    
  time=millis();
}

void loop()    // this section of code is repeated indefinately (until Arduino loses power, at least)
{  
        float pi=3.1415;
        int x;            // Selected spatial x
        int y;            // Selected spatial y
        float tht=0*180/pi;      // Selected tool angle
        int dx;
        int dy;
        
        int xt;
        int yt;
        int rt;
        int th1;
        int th2;
        int th3;
        int a;
        int b;  



// ________________________________________________________________________________  
for( ;millis() <=2000;){
   for ( ;millis() <= 2000;){     
      
      float dy = map(millis(),0,2000,500,100);
      float y = dy/100;
      float x = 6.0;
      float xt = x - .1443 - 2.178*cos(tht);
      float yt = y + .7475 - 2.178*sin(tht);
      float rt = sqrt(xt^2+yt^2);
      float a = 1/cos(rt/11);
      float b = atan2(yt,xt);
      float th1 = (a + b - pi/2);
      float th2 = pi - 2*a - pi/2;
      float th3 = tht-th1-th2;
      
      ang1 = th1*pi/180;
      pos1 = -10*ang1+1465.5;
      servo1.writeMicroseconds(pos1);
      
      
      ang2 = th2*pi/180;
      pos2 = 10.556*ang2-1450; 
      servo2.writeMicroseconds(pos2);
      
      ang3 = th3*pi/180;
      pos3 = -10.734*ang3+1450;
      servo3.writeMicroseconds(pos3);

   


    time=millis();
    Serial.print(time);      // write the number currently stored in the variable time to the serial port
        Serial.print("\t");  // tab
    Serial.print(x);
        Serial.print("\t");
    Serial.print(y);
        Serial.print("\t");
    Serial.print(xt);
        Serial.print("\t");
    Serial.print(yt);
        Serial.print("\t");
    Serial.print(rt);
        Serial.print("\t");
    Serial.print(ang1);
        Serial.print("\t");
    Serial.print(ang2);
        Serial.print("\t");
    Serial.print(ang3);
        Serial.println("");
   }
   delay(1000);
   }      
}
2 
    int pos1 = 1465.5;   // variable to store the servo1 position as an integer

What is it you don't understand about the noun "integer"?

 float rt = sqrt(xt^2+yt^2);

You can't XOR floats - that's what the compiler is telling you.

3

Thank you for the prompt reply.
I am new to coding,and I will do a little more research into it to see if I can better understand. Would you have any suggestions for fixing this issue?
I had assumed that using floats would carry a higher precision down to the equations for pos1, 2, and 3 where the values would be rounded off.

4

Try

float rt = sqrt((xt * xt) + (yt * yt));
5

That definitely solved the compiling problem.
Unfortunately I'm still lost as to why my angles th1, 2 and 3 are approximately 0.

Back to researching!

Thanks!
Moerdith

6

Unfortunately I'm still lost as to why my angles th1, 2 and 3 are approximately 0.

So, print the intermediate results that are used to calculate those values.

It may help you if you get rid of all the "int" variables you declare but never use at the top of "loop()".

7

So, print the intermediate results that are used to calculate those values.

That's what I have been doing. The research is to determine why there are issues within the calculations.
My issue seems to be within the converting from the angles th1, th2, and th3 from radians to their corresponding angles in degrees. I have tried making the values float, however that doesn't seem to effect the solution.

ang1 = th1*pi/180;

EDIT: Well now I feel a little slow... I used the wrong equation: 180/pi is the conversion from radians to degrees.

8

The compiler is going to be a little happier if you tell it when a statement is expected to perform a floating point process. Something like:

float th2 = pi - 2*a - pi/2;

is more safely written:

float th2 = (pi - 2.0) * ((a - pi)/2.0);