I started this project about 8 months ago. The first thing I tried was to just slap an arduino on top of a Raspberry Pi and attach a motor driver board. In the photo with the chassis you can see the Arduino-compatible (from Watterott) on top of the RasPi. Fine and dandy, except the motor controller gets jammed to 11, if I increase input voltage over 8 volts and start a motor.

Well, at least my web interface works.