Lesson4Week6.markdown

@@ -112,21 +112,23 @@ public class PIDCarController {
 	 
         LCD.clear();
         LCD.drawString("Light: ", 0, 2);
+        LCD.drawString("Error: ", 0, 3);
         LCD.drawString("Turn: ", 0, 4);
         LCD.drawString("PowerA: ", 0, 5);
         LCD.drawString("PowerC: ", 0, 6);
 	 
     while (! Button.ESCAPE.isDown())
     {	
-    	
     	LCD.drawInt(LightValue,4,10,2);
     	LCD.drawInt(error,4,10,3);
     	LCD.refresh();
 
         int LightValue = light.readValue();
-    	error = LightValue - offset;			
 
+        //calculates the error by subtracting the offset
+    	error = LightValue - offset; 
 
+        //calculates the derivative by subtracting the current error with the last error    										
     	derivative = error - lastError ;    		
 
         // To avoid wind up and high integral value, we reset it to zero if the error equals