the goal would be a 3-4ft robot which is sturdy enough to fall down stairs and survive, can push buttons, go over uneven terrain, be remote-controlled via cellular modem, be equipped with a webcam and screen and contain a locking storage compartment.
i had some fancy plans of how i'd make it work just like a real R2D2. it'd probably be very costly and take something like 3 years to build, based on my current knowledge. so i simplified.
- do away with complexity and just strip a golf cart - make it 2 wheel drive with the 3rd wheel just a castor
- body could be two trash cans for more support
- a rectangular frame to simplify fabbing - though mandrel-bent isn't complicated or expensive these days
- borrow someone's mechanic shop, i know people with welding stuff
- all solid state electronics
- there'd need to be significant ballast on the caster wheel, and lowest center of gravity possible; probably put the battery by the caster wheel and cpu behind it
- driving would be firmware-controlled tied to the proximity sensors and the CPU would override
- buying a pre-existing arm would be best. otherwise, one pneumatic lifter up out of the can, and one that shoots out forward to push a button, with the webcam on the head
- firmware would probably take the longest to finish
- could put a hole in the middle of the can and turn this thing into a sex toy, rent it out to parties to subsidize the costs
- an LCD "face"
- to simplify the "CPU" could use an android phone or netbook. if there's a power failure you could still communicate with it (and locate via GPS)
- by using trash cans for the body and reinforcing the outside with a mandrel-bent tubular steel frame i could put a keg inside and make it a self-propelled kegerator
Now all I need is about $3000 and a nerd with a mechanic shop and a big heart.