We have previously set the connection problem to the network via wifi key.
That leaves the power part of the Raspberry Pi and motors for your robot can move it without constraints.
Power Raspberry Pi
The Raspberry Pi requires a regulated 5V / 1A supply.
So I opted for a stick battery Sony : http://www.sony.fr/product/fournisseur-energie-portable-usb/cp-els
Engine supply
Coming soon