The following is excerpted from Actuators and The Power to Do Tasks, written by Lidia Pereira Rose, and published by Cavendish Square, 2017.

Have you ever had an itch on your back you just couldn’t reach? Many of us use a pen or pencil to reach the itch - other people will scratch their back on a vertical surface like a bear. But what do you do when a Space Station’s manipulator needs to reach somewhere it can’t?

Building manipulators is one of the great joys of robotics, being flashier and rather more fun than your standard drivetrain. It is also one of the greatest frustrations, and nothing can truly illustrate that better than the history of the Canadarm2. The Canadarm 1 was the primary manipulator used on the now-retired Space Shuttles. It was much like a human arm, with six degrees of freedom, with its reach additionally limited by its length. It could hold things out, and bring them into the shuttle’s cargo space, but its dexterity was about as limited as a human’s. However, when the International Space Station came about, the Canadarm2 was commissioned to assist in building the space station, as well as perform tasks after its completion. The second Canadarm is properly called the Space Station Remote Manipulator System. The name alone should give you an idea of how much it was expected to accomplish! A limited reach would have been unthinkable in the situation- and multiple manipulators just as impossible. Some serious out-of-the-box thinking was required, and sure enough, a unique solution was developed for the Canadarm2.

The Canadarm2 has seven degrees of freedom, and is symmetrical over its center point. Because of this, the manipulator can reach down and grab one of the many power nodes located on the ISS, and connect itself to power and data through its end effector. An end effector is the part of your manipulator that interacts with the environment, like your hand does for you. We don’t have the benefit of this next part on our hands, though - the Canadarm2 can detach the “shoulder” it was using before, and use it as the new “hand”. In doing so, it can swing itself along the ISS, much like a human using monkey bars. With power nodes all over the space station, the arm has access to virtually every point on the exterior of the satellite. For repairs, docking assistance, and assisting with assembly, the versatility of the system is virtually indispensable. What’s more, thanks in large part to the reduced forces in microgravity, the 1.8 ton arm runs on about as much power as a hair drier. Working along with several other robotic manipulators, the Canadarm can intercept satellites, position parts for retrieval or placement when astronauts spacewalk, and even work with another robot named Dextre to perform certain repairs and external maintenance.

In a more down-to-earth twist, technologies pioneered for the Canadarm are now being used to remove otherwise inoperable tumors. While still remotely controlled by a surgeon, robotic arms can be much steadier and more precise than human surgeons, and can work in more difficult spaces. One of the technologies being developed allows surgeons to operate on a patient in an MRI machine, which has never before been possible. A great reminder that solutions can come from anywhere- out of nowhere, or outer space.