Add details for USB power supply

Author: wassfila

content/robotics/USB-Power.png

@@ -11,7 +11,31 @@ A car robot platform based on the Yahboom Rosmaster X3-Plus mecanum chassis, cus
 
 Photo from the latest development stage. The robot can be controlled with PS4 joystick over bluetooth and using python and Rosmaster_Lib.
 
-## BOM
+# Versions
+
+This robot will be built in stage with progressive functionalities
+
+| version | Description | Peripherals | Batteries | USB |
+| ---     |     ---  | --- | --- | --- |
+|Manual | Test car movement with a Joystick| WiFi, M-Control, BT Joystick | 12_V | Raspi_Ports |
+|Navi | ROS2 Navigation with Lidar | WiFi, M-Control, Lidar | 12_V + USB_Bank | x1 Hub |
+|Navi+ | Navigation with Depth obstacles avoidance | WiFi, M-Control, Lidar, Depth | 12_V + USB_Bank | x1 Hub |
+| VR | Stereo Camera for Virtual Reality telepresence and inspection | WiFi, M-Control, Lidar, Depth, Stereo_Cam | 12_V + USB_Bank | x1 Hub |
+| Interaction | Interactive voice communication | WiFi, M-Control, Lidar, Depth, Stereo_Cam, Mic_Array, Speaker | 12_V + USB_Bank | x2 Hubs |
+
+# USB Peripherals
+In order to extend the robot runtime, in addition to the the 12_V motors board battery, a second USB power bank is used to power the Raspberry Pi 5 and its USB peripherals.
+
+![USB-Power](./USB-Power.png)
+
+The Raspberry Pi 5 could draw 5V@5A profile, but the max a USB power bank can deliver @5V is 5V@4.5A which is not a big difference. We also notice that if we power the USB Hub, we can fully cover the maximum power the Raspberry Pi 5 could draw.
+
+* Without drawing power from the Pi USB, it runs at 3 W when idle and could reach a max theoretical of 15 W
+* Weger Power Bank 20000 mAh can deliver 22.5 W and has 5V@4.5A on x2 USB outpus and 5V@3A on USB-C
+* Acer USB-3 Hub draws the USB profile 5V@2.5A so a theoretical of 12.5W but in practice ~ 5.2 W would be needed
+
+
+# BOM
 The Bill Of Material consist of the following items
 
 ### chassis