Multi-loop PID Controller Research Articles

Tuning of Multiloop PID Controllers Based on Gain and Phase Margins Specifications

An analytical method of tuning multiloop PID controllers based on gain and phase margins specifications is presented in this paper. The proposed design method can tune the multiloop controllers on-line and in real-time to meet specified system robustness and performance. The design method can be easily combined with existing process identification techniques to implement self-tuning multiloop controllers.

Dynamic matrix control of diaphragm-type chlorine/caustic electrolysers

Abstract Dynamic matrix control (DMC) is now widely used in industrial control, and when properly applied results in significant savings due to improved efficiency and reduced off-spec product. The objective of this paper is to implement MIMO DMC on a simulated diaphragm-type chlorine/caustic electrolyser. A comparison between the MIMO DMC and traditional multi-loop SISO PID control strategy shows greatly improved controller performance and cell efficiency using DMC, which will result in reduced operating costs and increase cell diaphragm lifespan.

Multiple-loop PID controller tuning by the goal attainment trade-off method

An interactive multi-objective optimisation method has been introduced in this study for tuning multi-loop PID controllers. Several design specifications may be simultaneously considered in this optimisation problem. The multi-objective PID tuning, problem was then reformulated into the goal attainment framework. Minimisation of the attainment factor was used as a design index for checking the system whether it met the goals. A trade-off procedure should be performed to achieve the acceptable control effects if the goals were unsatisfied. The one-parameter tuning PID controller was introduced in this work so that the number of the tuning parameters of the multi-loop controllers was reduced. The interactive optimisation search was accordingly lightened. Two examples, a two-loop and a three-loop process, were given to illustrate the design concept.

Temperature Profile Control of a Rotary Dryer with Multivariable Model Predictive Control

This paper presents a control system for a rotary dryer having to cope with large load disturbances. In order to maintain the product moisture content and degree of oxidation at specified values. it is necessary to control the temperature profile of the material in the dryer. However, instead of controlling the entire temperature profile. the developed system requires only two measurements; One of these is the material temperature at the exit of the dryer. and the other is the temperature at which the drying mechanism changes from constant rate of drying to falling rate of drying, which is termed the critical point. A “soft sensor” was developed which can infer the position of the critical point from the material temperatures measured at three different points along the dryer. The developed 2x2 multivariable model predictive controller (MPC) when integrated with the “soft sensor” showed superior performance when compared to a conventional multi-loop PID control system