Impact of anti-aliasing filters on optimal sampled-data PID control

Abstract

In the paper the role of anti-aliasing filters is investigated based on control quality assessment of optimal PID controllers when using a Butterworth antialiasing filter prior to sampling versus sampling without any analog filter. Numerical results show that contrary to common belief possible benefits gained from anti-aliasing devices are very restricted.

Sampled-Data PID Control and Anti-aliasing Filters

“…The best results in the latter case are obtained when the continuous-time output is passed through a continuoustime Kalman filter, which depends rather on disturbance and noise characteristics than the sampling period, before being sampled. Similar results were observed in PID control systems (Blachuta & Grygiel, 2009a;b;c)and (Blachuta & Grygiel, 2010) In this chapter we summarize these results and compare them with LQG minimum-variance benchmark control using simple, but representative examples.…”

Frequency stabilized lasers for space applications

“…The advantage of rolling off noise and resonant dynamics must be weighed against the added phase delay to the closed loop system and the loss in performance from this lag. Blachuta 36 shows that a Kalman filter provides better performance when compared with an anti-aliasing filter. One other comment is important -closed loop bandwidth for both the PDH and gas cell is respectively ~0.1% and ~0.01% of the control system Nyquist sample rate.…”

“…As is well known, any signal content above the Nyquist sampling rate become aliased. The standard approach of adding an analog anti-aliasing filter does not always improve performance 35,36 . The advantage of rolling off noise and resonant dynamics must be weighed against the added phase delay to the closed loop system and the loss in performance from this lag.…”