Now for the design:
The continuous rotation servos will in the middle of a plastic base with gears mounted running to the back of the base were wheels will be mounted. There will also be wheels in the front. I will mount the snap switches to the front and back, with a bumper attached to each. Above the front bumper will be 2 head lights, which will have varying brightness based on the readings from a photocell mounted on the top. The switches will be mounted on the top as well. The Proximity sensor will be a few inches above the headlights.
Any suggestions or potential problems before I order the supply?
Have you considered using a single caster in front instead of wheels? You will get skidding action either way and at least a caster is made for it.
That also seems like a lot of battery to be dragging around, but then in a quick check I wasn't able to find any current draw info on those servos.
I'd look into powering the arduino from one of the those 4xAA using nimh cells (4 alkalines is too high a voltage and rechargeables are better anyway) and using the other pack for both servos. But then without knowing the current draw its a hard call. I'm not saying your plan wouldn't work, just wondering how long this thing should need between charges.
Mainly I dislike 9 volts.
Other than that looks like you've put some thought into the list and I bet you can get something rolling around out of that.
i really like the idea of your project, i am fairly new and would like it if you get this in the exhibition section when finished. good luck!
and i would draw it all out on paper and see if there is anythink else you need
Couldn't find any specs on the current draw for those servos but I suspect that yes, you can power both off of 4 AA's. Your voltage will be at the low end of the operating range for those so they will not be moving as fast as possible but I imagine it would work.
As far as the caster that looks almost like it was made for this application :).
Alkalines have a higher nominal voltage of 1.5V, so they would be 6.0. They also are not rechargeable.
NiMH have a nominal voltage of 1.25V, but are rechargeable and actually tend to droop in voltage less under heavier loads than alkalines.
I use these, http://www.energizer.com/products/recharge/Pages/rechargeable-battery-charger.aspx for stuff like this. When using these batteries its much easier if you make sure you use them in pairs as the chargers generally only charge two or four at a time. Which is nice since 4 of them gives you a max of a little over 5 volts at max charge and it stays at 5V or so for a long time under light loads, making them useful for powering my arduinos.
Since your servos can operate at the same voltage I think simplicity of design calls for two packs as the cells will be interchangable and charging will be easy.
Two problems with 5, either of which would prevent me from using that number.
5 x 1.25 = 6.25V, which is the nominal voltage. They will be higher when fully charged meaning on a full charge you could be at 7V while freshly charged. If this were a bare DC motor I wouldn't worry about it that much but as this is (was) a servo it has electronics inside the box that I would fear frying with that much over voltage.
If you have 5 discharged batteries and your charger only charges two or four batteries at a time, how do you get all 5 charged?
If you do run unregulated battery power to the arduino, rechargeable and non-rechargeable batteries will not be interchangeable. You want 3 alkalines or 4 NiMH.
OK. So the new plan:.
Same as before but with a caster instead of front wheels, and two 4 rechargeable aa packs for power.
Any thing else you see as needing improvement?
