Generalized hold devices for digital-to-analog conversion in electronically controlled systems

Resumen

> This thesis deals with hold devices other than the zero-order hold > (ZOH), and therefore belongs to the field of sampled-data control > systems. It proposes a new application field for the fractional-order > hold (FROH) and a new design of generalized sampled-data hold function > (GSHF). Plant dynamics are assumed to be linear, time-invariant and > scalar (single-input, single-output).>> Specifically, we propose to use the FROH not to improve the system > output performance, but the system input performance as measured by > the reduction of the integral of the square of the transient control > signal (ISU). When used together with lightly damped resonant systems, > software-based simulations show ISU reductions of over 50% in step > responses, with barely affecting the system output performance; see > [1]. We also present a new design of GSHF that merges the advantages > of the FROH (ZOH output under constant input) with those of > conventional GSHFs (as many free parameters as desired), which makes > it possible to arbitrarily place z-domain zeros (like conventional> GSHFs) while avoiding intersample ripple under constant input (like > the FROH); see [2].>> Finally we provide experimental, hardware-based evidence obtained on a > small-scale positioning servomechanism. For the FROH application, the > reductions in true energy consumption turn out to be comparable to the > reductions in ISU anticipated. For the GSHF design we have seen no > issue that would prevent its use beyond academic environments, > particularly that the hold functionality can be easily accommodated in > controller idle time; see [3].>> [1] http://dx.doi.org/10.1049/iet-cta.2013.0740> [2] http://dx.doi.org/10.1016/j.automatica.2012.03.004> [3] http://dx.doi.org/10.1016/j.conengprac.2014.01.006