Dynamic Set-Point Weighted Fuzzy PID Controller

Abstract

A fuzzy PID controller with dynamic set-point weighting technique is proposed. Fuzzy PID controller is realized by combining the control actions produced by a fuzzy PI and fuzzy PD controllers with suitable output scaling factors. Input to the fuzzy controllers i.e., error and change of error are calculated from the dynamically weighted set-point for each sampling instant. The dynamic weighting factor is calculated online from a simple relation consisting of normalized change of error and normalized process dead time. The proposed dynamic set-point weighted fuzzy PID controller provides a significant amount of performance enhancement for higher order processes with dead time, verified through simulation as well as real time implementation. Unlike to the conventional fixed set-point weighting which offers only improved set-point response, our proposed dynamic set-point weighting is capable to provide simultaneous improvement during both the set-point tracking as well as load variation with considerable robustness in close-loop behavior.

Fuzzy rule-based set point weighting for fuzzy PID controller

“…Later, another effective weighting strategy known as dynamic set point weighting (DSW) for PID controllers is reported in [19,20] where the weighting factor is varied depending on the current process operating conditions and hence capable of providing an overall performance enhancement. To overcome the limitation of improper tuning for fuzzy controller which results undesired oscillations during closed-loop operation, dynamic set point weighting (DSW) mechanism [21][22][23] is incorporated while designing the FLC. DSW technique is capable of ensuring lesser oscillations while tracking new set value and faster load recovery.…”

An online dynamic set point weighting scheme for PID controller

“…So, to attain this desired goal set point weighting technique is an effective mechanism which can minimize the overshoot but at the cost of increased rise time. Hence, in literature we can find that various set point weighting schemes have been proposed by the researchers [6][7][8][9][10][11][12][13] to make the set point weighting more effective and easy to implement for single input single output (SISO) control loops. Fixed set point weighting (FSPW) [6] and variable set point weighting (VSPW) [7] are some of the well studied examples of it.…”

“…Continuously varying set point weighting technique is suggested for conventional PI and PID controllers in [10] and [11] respectively. Another set point weighting schemes are reported in [12,13] used in fuzzy PI/PID controller. Mostly the reported set point weighting schemes are targeted towards performance enhancement of the controlled variable during set point response, merely they provide any improvement during load rejection.…”