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This is not a job for R/C, this is a job for robotics. Do you really want to manually control the thing? A microcontroller, a few servos and a battery, and you can create whatever movements you want. You can do things with off the shelf components that would amaze. If its just a couple servos controlling the movement, they will run a long time on a 6v rechargeable battery. The servos don't need to be large if you design it well. Make sure everything is counter balanced to require the minimum amount of input to get the desired motion.

I have built a couple robots using OOPIC controllers, but I think they have went out of business. Parallax has been in the business along time. There is a controller out there by Trossen called the AxonII. Nice because it has everything onboard. Servo controllers, room for sensors, USB input....etc.