You may have noticed in the circuit below that I have added a Bluetooth module. I was also was wondering if the weak motors were due to lack of current from the AA batteries so I have ordered a 7.4V lithium Polymer battery and charger. I could use the Nano to monitor the battery voltage and even send this value over Bluetooth as well as indicating low battery voltage with a LED.
Another thought I had was adding a Knight rider type 8 led display to make it look like the robot was scanning. This would require a second Nano and/or a shift register circuit. But this is after everything else is working.