Artificial muscles robotic arm with full range of motion [video]

I bet the "muscles" themselves are quite quiet.

Great question. And yes, you can have lots of smaller ones to do the work of a few larger ones. The strength (stress) comes essentially from the cross sectional area of the muscle (or bundle of). And no matter how thin you make the spaghetti, you still need an equivalent volume of it to get the same cross section, For a given length.

The reason speed, as in how many times a second you can make it contract and lengthen, is a limiting factor comes down to good old force = mass x acceleration. Want to make it go faster?then you need higher pressure. So now You have a lot of water you need to move at high pressure with very rapid acceleration. This means the scale of the pumping equipment gets prohibitive very rapidly.

Real muscles work at a fundamental level by a kind of ratcheting mechanism between proteins that pull each other together. This process can happen very quickly. Mammal muscles don’t need to pump lots of liquids around with high acceleration and velocity. So there is actually a lot less inertia from moving mass in real muscle.

Another issue I didn’t touch on in my earlier post is that this kind of muscle is very difficult to do strain and force sensing with. To make motion with this kind of actuator that is both rapid and smooth is extremely difficult and still an open problem.

Long answer: I think that the more minds there are working on this (or any other interesting) problem, the more progress will be made. And we shouldn’t let the perfect be the enemy of the good enough.

The field of robotics, and especially soft robotics like this, is so new and uncharted that individuals tinkering in their garage can and have made real advances for the field.

That said, really good control systems for these kinds of actuators are something very much lacking. The human nervous system, and in particular the vestibular system is so absurdly effective, efficient and complex all at the same time that it boggles my mind. Nothing anyone has ever designed has ever come close to that level of functionality. But to make a robot that can do human things, we need that level of functionality. We need to have really good proprioception which is integrated with force and feedback sensing.

To give an example; open a bag of potato chips and pull out a decent handful. Now eat the chips one by one out of your hand without dropping any and without using your other hand. I dare say you can probably do this, and without crushing the chips in your hand. You can feel just how much force to apply, you can feel where to place your fingers so that all the chips are held just so. You can make subtle adjustments after each chip is taken away.

There is no robot hand in the world that can do that simple task. Ask any arm amputee. And to get to that point, a lot of really difficult stuff has to be invented and worked out. I suspect this is a problem which will be solved piecemeal, over time, but much of the fundamental work in things like the mathematics of motion control, material science and compliant mechanisms will come from very well funded labs. If I had to guess, I give a 60% chance a robot can do the chip eating task within a 5 years. And 85% within 10 years. (Especially if the work of my team pays off)

https://www.nature.com/articles/d41586-019-01216-4