Unified approach for weighted sensitivity design of PID Controllers with Smith Predictors
Date
2022-11-25Author
Alrishan, Abdulkarim
Watkins, John Michael
Emami, Tooran
Metadata
Show full item recordCitation
A. Alrishan, J. Watkins and T. Emami, "Unified Approach for Weighted Sensitivity Design of PID Controllers with Smith Predictors," 2022 Australian & New Zealand Control Conference (ANZCC), 2022, pp. 230-235, doi: 10.1109/ANZCC56036.2022.9966952.
Abstract
This paper combines a Smith Predictor with an
approach for graphically determining all ProportionalIntegral-Derivative (PID) controllers in either continuous-time
(CT) or discrete-time (DT) domains that meet performance
specifications expressed in a form of a weight on the sensitivity
transfer function using Hardy-Space (H∞) control. A Smith
Predictor (SP) is often used when designing a controller for a
system that exhibits a “relatively” large delay that may cause
the system’s relative stability and/or performance to
deteriorate. The PID controller gains, namely Proportional
gain Kp, Integral gain Ki and Derivative gain Kd, will be
determined graphically using only the frequency response of
the systems’ components, i.e., plant with delay and SP
structure. The inclusion of a SP along with a PID controller can
significantly improve stability margins and/or performance
when compared to relying solely on a PID controller. The
improvement can be observed even if there is a mismatch
between the actual process and its corresponding SP model. By
using the delta operator, the same procedure can be applied to
either continuous or discrete time systems, hence a unified
approach. The stability boundaries of the PID controller will be
determent graphically where within the boundaries, nominal
stability is guaranteed and weighted sensitivity requirements
are met.
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