Google's recent purchase of the defense contractor Boston Dynamics has raised eyebrows, and also brought the inevitable – if overblown – comparisons between Google and Skynet

Boston Dynamics is a pioneering robotics company that makes machines such as Big Dog, which is capable of carrying loads of supplies over rough terrain, as well as Cheetah (see video below), a four-legged robot that has attained the highest land speeds yet of any robot with legs (29 mph).

The Cheetah mimics the movements of the real animal and uses hydraulic pumps and a boom to get it running.

So how might these machines be used? Google could develop an amazing civil robot to aid the handicapped as well as a security bot that will win lucrative military contracts.

Watch here: