  Precise control is an essential and elusive quality of emerging self-driving
microscopes. It is widely understood these instruments must be capable of
performing rapid, high-volume, and arbitrary movements for practical
self-driving operation. However, stage movements are difficult to automate at
scale, owing to mechanical instability, hysteresis, and thermal drift. Such
difficulties pose major barriers to intelligent microscope designs that require
repeatable, precise movements. To guide design of emerging instruments, it is
necessary to understand the behavior of existing designs to identify rate
limiting steps for full autonomy. Here we describe a general framework to
evaluate stage motion in any electron microscope. We define metrics to evaluate
stage degrees of freedom, propose solutions to improve performance, and comment
on fundamental limits to automated experimentation using present hardware.
