Monday, January 13, 2025
FPath: Actuator Dreamin’
More and more, as one attempts to move down the Feynman Path it looks as if actuators are the real roadblock.
In retrospect, this should have been obvious if one pays attention to what one "does not see" as opposed to what one "does see". A casual survey soon turns up a dearth of viable millimeter scale actuator designs and yet people have been making millimeter scale devices for over 100 years. Yes, some actuators exist, but far less than one might expect. A quick search on terms like "millimeter scale actuators" soon reveals that many are only "milli" in one dimension – if that.
So what causes the problem? Why the shortage? Well, some of it is probably due to the fact that commonly available machine tools are quite accurate at the millimeter scale. In other words, if you need to move something 0.1 or 0.01 of a millimeter this is easily within capability of macro devices – so why bother creating hard-to-work-with millimeter scale actuators for the purpose.
The other reason is that there seems to be a gap between the scale at which electromagnetics stop working efficiently (centimeters) and electrostatics start working efficiently (microns). Simply put, finding a way to actually actuate anything at the millimeter scale is hard and so it is easier just to ignore the problem and find some other way of doing what you need to do.
Does this mean there is no point to milli-scale actuators? Why not just skip to the micron scale and have done with it? This is essentially what the MEMS people are doing, however, since there is nothing at the scale above them, things like assembly or complex multi-material manufacturing of devices is not practical. Machine tools and repurposed semiconductor fab equipment are suitable for the creation of parts but not really intended for construction, manipulation or operation.
The Feynman Path is intended to address this issue by working down the scales leaving behind a toolkit at each scale able to build and operate the tools and devices below it. Maybe milli-scale actuators really are impractical and a jump right to the micron scale is necessary. Nevertheless, an exploration of the millimeter scale actuation space would seem to be worthwhile - no need to give up on it without putting in some time.
So, having got the closed loop control thing operational, it is time to put that area of exploration to one side and begin work on millimeter scale actuators. I have some ideas…. more in future posts.
Labels: Feynman Path, FPath, millimeter scale actuators, Nanotechnology
