In an electrical "freak" accident that took place over 40 years go, Les Baugh lost both of his arms. He made history this summer by being the first double-amputee to control two robotic arms simultaneously. Before suiting up, Baugh was first examined by doctors in order to find the correct nerves and muscles. By doing so, doctors were able to find the right muscles and nerves capable of translating movement to the prosthetic arms. A virtual reality exercise was then needed to walk Baugh through on how to control the two terminator-like arms.
Image source: Johns Hopkins University Applied Physics Laboratory
But it's more than just an exam and a short training exercise that's needed to control a prosthetic arm. Baugh had to undergo surgery to reassign existing nerves. This relatively new surgery gave Baugh complete prosthetic control simply by the power of thought. More on the targeted muscle reinnervation surgery can be found at the laboratory's site.
Researchers estimate that this type of prosthetic technology will improve significantly in the next 5-10 years.
Source: Johns Hopkins University Applied Physics Laboratory