There are 2 repositories under android-usb-host topic.
Usb serial controller for Android
Open source library to access USB Mass Storage devices on Android without rooting your device
Android USB mass storage, meet FAT16
Code for creation of a prototype model of a social robot :electric_plug: by integrating different domains like Android:iphone:, ML:bulb:, Image Processing:foggy: etc
Work with USB mass storage on Android, sans root