I ran into this recently, on some KRC2s with kinematically integrated external axes. Briefly, the external axis in question was being used as a very large "rotisserie" of sorts, rotating a very large (~10m length) mandrel while the robot's carried tool carried out operation on that mandrel.
The thing was, these robots had been in service for many years, and new part models, with new mandrels that have very different weights and CoGs than what the external axis was originally tuned to. And with some of the newer mandrels, with really extreme CoG differences, the customer was seeing some minor but present effects in the motion of the external axis.
Also recently, I was working on some ABB IRC5s, which have Load Data variables for external axes, and the Load Data could be changed programatically when, for example, a heavy parts was loaded/unloaded to the external axis.
This got me thinking: I've never seen an equivalent to this for KRCs. Just PID-tuned the external axis, usually to the wort-case load conditions, and used that setting forever.
Do KUKAbots have a means for changing an external axis payload, or tuning, on the fly, and I just never came across it? I can see a situation where someone builds a number of different "tools" for an external axis that have such different CoGs, inertias, etc. that a single tuning of the axis might not work for all of them (or might be too slow).