*Much credit must be given to the various sources on the Internet I used when creating these two versions - all I did was mix things in a slightly different way.
Version 1 - Roomba
The Raspberry PI presents a web interface for the user, using PHP to send serial commands through the USB to TTL adapter to the 8 pin DIN plug connected to the Roomba. The Pi is powered via the 5V DC to DC buck converter which connects to the Roomba battery.
* The Roomba can output a LOT of power on it's TX line - and I accidentally fried two Pi's USB capabilities while testing this due to my carelessness. Make sure your USB - TTL adapter can step voltage down to 3.3 volts on it's RX line.
A tablet is mounted to the Roomba using two 3.5 foot L shaped lengths of aluminum. At the time, TASKER was used to automatically answer the skype call on the Roombas Android tablet.
The web interface could call a preprogrammed function in the Roomba to dock itself on it's charging dock. Having an inductive charger mounted to the Roomba dock allowed the tablet to charge. In retrospect, I probably could have had it charge from the Roomba directly.
The Roomba had to be heavily weighted to keep it from being too top heavy so it would not flip over, and the dock needed a slight cutout on it's bottom to allow the heavier Roomba to successfully dock.