Take a look at Honda's latest vehicle:
They've reinvented the "Segway";-). Also reminds me of a robot I once saw that hopped around on ONE leg. Not exactly high precision movement but but it was easy to analyze. It was used as a learning tool to decide how best to approach the problem of keeping an autonomous robot from falling over. If the Honda model will stand still on its own it may have a large gyroscope in it which would limit battery life if it can be carried in one hand. OTOH if the control system is good enough it may not need a gyroscope.
John