SPM force feedback
This page is more about force feedback for the human operator in order to develop an intuition for nanoscale forces.
This is not so much about force feedback for the automatic control loop.
The Δf signal is usually used directly used for that in "constant Δf mode" (wiki-TODO: (double check)).
Constant height mode is commonly used for nc-AFM.
Why not just feed forces to machine learning AI?
Q: Why not hook it up to machine learning AI? Doesn't that make force feedback for human operators obsolete?
No. But hooking up AI can (and should) be done too. This does not make force feedback for human operators obsolete.
There is still the need for communicating the results of the AI (in terms of it's understanding) to human operators and
vice versa communicating guiding envelopes for the AI's further desired actions.
Communicating forces directly as what they are, forces,
rather than via some other indirect "visualization/audioialization/textualitation"
should very much be the most efficient (and thus most enjoyable) communication channel.
nc-AFM (atoic force microscopy) does not meature foces but stiffnesses
A historic naming accitent. Just like nc (non contact) is one too.
The nc-AFM technique is actually measuring surface stiffness rather than surface forces.
So it is actually stiffness feedback rather than force feedback.
Forces can be reconstructed.
Since the delta_f signal is averaging over the oscillation amplitudes range
it is not a simple integration but rather some more complex method needs to be used.
In the small amplitude limit the math should become equivalent with a simple integration again fro any used method. (TODO: Sow these limits for the two methods eventually. as this may help in intuition.)