diff --git a/README.md b/README.md
index 87d7dbf..51fa811 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,8 @@
 # Auto-Docking-Design
 
+# Demo video
+* https://www.youtube.com/watch?v=8TJdYG-1yr4
+
 # INTRODUCTION
 * This is the auto docking design draft for the ANDBOT.
 * The same design could be used in Rogby, Angel and Roadbot.
@@ -7,14 +10,16 @@
 
 # COMPONENTS
 * On docking station
- * IR emitter 
+ * One IR emitter 
 * On ANDBOT
  * Two IR receivers 
  * microSW
 
 # BASIC OPERATIONS
+## Architecture
 ![](https://docs.google.com/drawings/d/10qjkzlVpxTzHJOy8nBXIwdnfUWQLuOGBx5gQOHoDPro/pub?w=955&h=878)
 
+## State diagram
 ![](https://docs.google.com/drawings/d/1y88r8ekS2AH1VXI44CYqL3lbkHgwUZl5kNnLzkqsd8c/pub?w=960&h=720)
 
 * We will use ROS navigation to command ANDBOT to move to the landing point, which should be in 0.7 meter in front of the docking station. The ANDBOT's back will be facing to the docking station.
@@ -23,8 +28,7 @@
 * Then, ANDBOT will start to do PID control to move to the docking station and keep the two IR receiver reading balanced.
 * Until the microSW on.
 
-# Demo video
-* https://www.youtube.com/watch?v=8TJdYG-1yr4
+
 
 # ISSUES
 * n/a