diff --git a/robot/arlo.py b/robot/arlo.py
index 80d3ba1..dcf07d0 100644
--- a/robot/arlo.py
+++ b/robot/arlo.py
@@ -8,7 +8,7 @@ START_VALUES = [60, 60]
 THRESHOLD = 1.05
 SLEEP_TIME = 2
 
-FOCAL_LENGTH = 0
+FOCAL_LENGTH = 1691
 
 def test_forward(arlo, l_power, r_power):
     arlo.reset_encoder_counts()
@@ -84,7 +84,17 @@ class Arlo():
         self.robot.stop()
 
     def estimate_distance(self, bounding_box):
-        average_left = bounding_box[0][0]
+        avg_left   = (bounding_box[0][0] + bounding_box[3][0])/2
+        avg_right  = (bounding_box[1][0] + bounding_box[2][0])/2
+        avg_up     = (bounding_box[0][1] + bounding_box[1][1])/2
+        avg_down   = (bounding_box[2][1] + bounding_box[3][1])/2
+
+        avg_width  = avg_right - avg_left
+        avg_height = avg_down - avg_up
+
+        avg_size = (avg_width + avg_height)/2
+
+        return (FOCAL_LENGTH * 15)/avg_size
 
     def find_aruco(self, image):
         aruco_dict = cv2.aruco.Dictionary_get(cv2.aruco.DICT_6X6_250)
@@ -95,7 +105,7 @@ class Arlo():
             parameters=aruco_params
         )
 
-        return zip(corners, ids)
+        return zip(corners, ids) if corners is not None else []
 
     def draw_arucos(self, image, bounding_boxes):
         for bounding, n in bounding_boxes: