[krisoft]

I think the reason these kind of simulations are fast enough is because they are very coarse and approximate. Don't think of asking how exactly the foam swirls around the individual longerons, more like a very rough estimation of which side of the tank the liquid is slumped to. Remember it doesn't have to be "exact" just close enough to be useful.

By their very nature model predictive controllers operate in a world where not everything is perfectly modelled. Engineers do their best and whatever is left is the "error" the controller is trying to deal with.

[Log_out_]

Or you compute variations ahead of time and do a situation based lookup, hoing through loops if a situation ressembles another one.

[keepamovin]

Maybe they don't need to model the fluid dynamics, they just need to detect the mass movement / acceleration forces caused by it, and use those sensor inputs to inform a picture that's fed into their correction thursting.

Sort of like how you can balance a few pitchers of beer on a tray in your hand by remaining aware of the weight, even when people remove one! hahaha :)

[m4rtink]

Still if there indeed is "free" mass moving about, you need to make sure your control inputs don't make it slosh harder, so you compensate for that, so it sloshes even harder, etc - basically avoiding oscilation. :)

[keepamovin]

Yeah..ah, control theory. Heh :)