Well I've almost had 3 weeks offline and got a ton of thinking done. The physical design is basically the same, going to use a PicAxe 14M to control four DC motors with two L293Ds. The picaxe will be optically isolated from the arduino, so if the motors, an IC or a wire shorts out and decides it doesn't want to go alone that it doesn't have the arduino as an option as a buddy in IC heaven or hell.
Basically, the arduino will send a message to the opto-isolated picaxe, then the picaxe will decode the message getting the data it needs to set the direction and speed of the four motors. This is a very simplified explanation of what will happen.
So far I have 7805 portion up and running so there is power to the picaxe and to the 595, the program/input selector will be 50% complete when I finish up the picaxe programmer circuit tonight. On the 595, a resistor needs to be moved from the ground pin to Q7, the ground pin needs to be wired to ground and then will have the comm pins to attach to the picaxe. I hope to get that portion done tonight, then I'd be about 20% done on the hardware portion. Having the programmer circuit done and the picaxe connected to the 595 would be an awesome accomplishment tonight.
So far just the 7805 portion done, so it has power, woot!!
Mech out