Is this a case of nuts and bolts becoming screws? In any case, South Korea's plans call for wheeled robots to act as prison guards. The wheeled robots are meant to relieve the burdens of their fleshy human counterparts. They can, according to the ABC report hold conversations, and they're equipped with sensors able to detect abnormalities such as violence and suicidal behaviour. Quite what they do then isn't made clear, although I guess it's tougher to stab a robot, or for that matter offer it cigarette bribes.
I can't see anything that could possibly go wrong with this. Oh yeah -- except this.