     Serial.print(down); 
     Serial.print(':');
     
-    int diff = abs(up - down);
-    if (diff > THRESHOLD_LDR_VIRT) {
+    int diff = up - down;
+    if (abs(diff) > THRESHOLD_LDR_VIRT) {
       return diff;
     }
     
     return 0;
 }
 
-int tkr_dist_horz()
+int tkr_diff_horz()
 {
     int left = analogRead(PIN_LDR_LEFT);
     int right = analogRead(PIN_LDR_RIGHT);

    
    servo_virt.attach(SERVO_PIN_VIRT);
    servo_horz.attach(SERVO_PIN_HORZ);
}

void loop()

    Serial.print(left); 
    Serial.print(':');
    Serial.print(right); 
    
    int diff = left - right
    ;
    if (abs(diff) > THRESHOLD_LDR_HORZ) {
      return diff;
    }
    
