pic: kiwi vex robot

[billbo911]

Originally Posted by Tom Bottiglieri

Well credit needs to be given where it's deserved. I got the equations for my kiwi code from the living genious, Joel Johnson.

Anyway, here's what you need to do to make it work:

PHP Code:

//Make sure variables are unsigned ints... rollovers WILL occur with signed ints
unsigned int trans_x, trans_y, rot;

//Grab inputs (x,y coords in rectangular coordinates and rotation rate)
trans_x = 254 - PWM_in1; 
trans_y = 254 - PWM_in2; 
rot = 254 - PWM_in4;      

//Limit vector length to 127
trans_x = (unsigned int)(37+(254*trans_x)/359);
trans_y = (unsigned int)(37+(254*trans_y)/359);

//Assign and limit wheel outputs
wheel_1  = (unsigned char)limit( (((2*trans_x) + rot) / 3), 0, 254); 
wheel_2 = (unsigned char)limit( ((601 + rot - trans_x - (168*trans_y/97)) / 3), 0, 254); 
wheel_3 = (unsigned char)limit( ((161 + rot - trans_x + (168*trans_y/97)) / 3) , 0, 254); 


This assumes you have a limit function, which limits an input value to upper and lower bounds.

PHP Code:

signed int limit(signed int value, signed int min, signed int max) 
 { 
      if (value < min) 
      { 
           value = min; 
      } else if (value > max) 
      { 
           value = max; 
      } 
  
      return value; 
 } 


That should be all you need, and it should work. (It took me about 2 hours to figure out the variables needed to be unsigned. )

Now I know why I like Tom (oh yeah, and Joe too ) so much!!

The problem is, now I have to go buy some omni wheels for this weekends project

BTW. Do you know how the constant values were determined (ie. 37, 359, 601, 168, 97, 161)? Also, I see you are using PWM_in4 for the rotation value. I assume this is off the left stick X-axis. Knowing these can help me modify this stuff for future projects.

Thanks again!!!!