t, i don't think we're in the realms of breaking physics. as a secondary, a typical arrow band o2 sensor is a closed loop system, it feeds back enough information to allow the engine to operate within parameters and try to keep a predefined air/fuel mix for the most efficient idle burn in terms of emissions output, it does not just indicate an error. this is what fuel trims are. some cars have closed loop all the way to WOT and will trim, as we advance ECU's and use faster cpu's we're moving away from archaic open loop systems with precomputed tables and trims, to directly using the sensors to determine correct fueling an advance etc, the whole engine moves away from being an open loop system to closed loop, the sensors can feed back enough info to do this properly, if a major fault appears that is something else, but to compare backlash to a loose steering wheel is another thing entirely, but i feel like this comparison may have run its course but we're in agreement of what an O2 sensor does i believe, and why its a good thing.
trims vs compensation for a failure, two different things. the ecu will say, hold on we're getting a tad crazy with these trims here and throw a warning code to the operate, backlash compensation to me is the same thing, agreed tolerances and where it can, and can't work, it does work in some scenarios, not in others, not having it means it can never work.
you seem to be looking from the point of view worst case, i'm looking at from the pov of best case, in where it is a useful feature, sure maybe thereis some thing i can learn that i can write gcode or cam up so that i no longer need it, but i'm not there yet, to me i'm still in the realms of i can draw a circle that turns out to be an oval, i can draw on oval that becomes a circle, which of course is a gross oversimplification of it, but thats my pondering over coffee and not being an experienced machinist. I do get that experienced machinists say remove all the mechanical slop and stop dreaming about backlash compensation, but that takes a while to achieve, i'm ok with working within the limitations as i improve the build and race towards 0.
roger, we're doing an incremental build, and are at stage 1 as it were, with 7.62µ of backlash at the moment. the idea is to keep improving the parts we're making with each incremental build of the machine, and improving it, the goal being not to need backlash compensation at all, but for now its extremely handy.
we could be the guys in the pits arguing about splitfires and monster cables, or the guys on track drifting around corners in a beater.