Motor Control System for large Robot?
So I am working on building a robot using wheelchair motors. I'm trying to control it via an arduino potentially but I'm not sure how to do this. My plan is to potentially use an 8channel 10 amp relay board connected to the arduino, but I'm not sure if 10 amps would be enough for the wheelchair motors? Also how do I go about actually powering the motors (12v Lead Acid Battery?) and interfacing that with the arduino (can I?). My other problem is that I would like to have at least a couple servos on each of two arms of the bot....so could I potentially control all that with the same arduino or would I need either a second arduino or an arduino mega with motor shield to do that?
My other problem is navigating/control.....
For that I'm thinking of using an ultrasonic ping sensor or two if that's possible, again I don't know if I can fit all these things on an arduino or not. and Lastly to actually control it, I know I should be able to program it autonomously with the arduino but what do you think is the best way if I wanted to be able to manually control the bot as well?
Thank you so much for any guidance you guys can give on this large project!