Generalized sampled-data hold functions with asymptotic zero-order hold behavior and polynomic reconstruction

We present a generalized sampled-data hold function that combines arbitrary zz-domain zero-placement ability with zero-order hold behavior under constant input, thus exhibiting minimal intersample ripple by design. Our hold can be regarded as a generalization of the fractional-order hold, with a polynomial instead of a simple linear pattern, and therefore with as many tuning parameters as desired. Moreover, the polynomial approach turns out to provide a simple mechanism of control energy minimization. Among other benefits, all these features help to achieve qualitatively better perfect model referencing, because problematic sampling zz-zeros or the intersample issues of the conventional generalized holds need no longer be endured.