Robots with no wheels or legs nevertheless can move about by jumping in any direction to self-assemble into any shape necessary to solve a problem at hand. Eventually they will be downsized small enough to swarm over the landscape forming smooth arbitrary functions like the "liquid metal" robots in Terminator-II: R. Colin Johnson @NextGenLog
Modular robot used internal flywheel (pulled out here) to give it the ability to move without legs or wheels. Further Reading