Over at the Fw:Thinking YouTube page for the Human+ episode, a user left the following comment:
Well if they could make an arm that would strengthen itself from induced stresses and load, similar to how [an] athlete would strengthen himself....
This is an interesting idea. My first reaction was to dismiss it entirely. Why would you create an arm that requires exercise to lift heavier things? Why not just crank the arm up to 11 in the first place? There's no reason a robotic arm would need to build up strength the way our muscles do. At least, not at first glance.
The viewer followed the comment up with another one, saying that it was an idea for an upgradable arm. But again, why exercise to upgrade? Why not just download software, or switch out hardware parts, or push a few buttons and turn a few dials? I guess I'm just asking why would I need to put forth any effort?
But upon further thought, I came up with one reason it would be a good idea to build exercise into a robotic prosthesis. Your robot limbs would still be attached to flesh at some point (I'm assuming we haven't entered a futuristic world where our entire bodies are synthetic). For example, let's say I've replaced my right arm with a robotic limb. It joins my torso at my shoulder joint. Everything below that joint is bionic.
If that robotic limb were significantly stronger than my old fleshy arm right out of the gate, I could see some problems. While the arm might be capable of lifting much more weight, my torso would still need to bear that load. I could give myself a severe injury if my body isn't prepared to handle the stresses put on it as I use my new limb.
But what if the arm had a built-in limitation that prevented me from using its full capabilities right away? What if I had to perform exercises, particularly ones that strengthen my torso to help endure the stresses I put on it? If the arm very gradually reduces those limitations, I might be less likely to hurt myself.
Even with this limitation in place, an arm could only be so strong before you run the risk of hurting yourself. We'd have to design limbs with this in mind. And you wouldn't really be building up strength in your robotic arm so much as reducing the dampener on your robo-bicep.
It may seem a little silly to think about such things when we don't yet have robotic limbs that are demonstrably superior to our human ones. I guess it is a little ridiculous. But it's good to remember that even if we create robotics that are in every way superior to ourselves we'll still need to limit their capabilities if we make them part of us.