Yup!
It follows that, any system you can increase the order of, while maintaining control of the poles, can be improved in identical fashion. Take the voltage mode SMPS for example: it has a two pole output filter, plus one more for the controller (assuming a traditional dominant-pole or pole-zero controller). Downside, the filter pole depends on the attached load, so you can only adjust it to, say, a 3rd order Bessel or Butterworth or whatever, for a given load.
I forget if you can do that with higher order compensators (i.e., more than one integral term), or if the poles stack rather than split, so you have no control over them (integrators at least must, because you only have one degree of freedom per integrator -- its gain -- and the product of any number of integrators still only has one gain term).
It might be doable with a chain of error amps (i.e., one loop is the "plant" of the next loop, and so on), where pole splitting does occur; but it need not be straightforward what the trajectory of all those poles is, and if you can coax them onto a circle or ellipse for anything, as needed for a known filter type. Or if the result is any less sensitive to source/load conditions. (In other words: you can try playing with your piezo stack and compensating it in this way, but you're much more likely to be fruitful, using a more conventional method like cancelling the dominant resonance in the loop.
)
Tim
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