PID Tuning Rules Research Articles

On-line relay identification, assessment and tuning of PID controller

Abstract In this paper, we present an approach using relay feedback for automatic identification of the PID configuration and parameters in existing and operational closed-loop systems. During the duration of the same experiment, the control performance may be evaluated, providing an assessment of whether the current control parameter set is adequate and if re-tuning is necessary. Systematic and on-line automatic PID tuning rules are further developed and provided for common configurations of PID control. Simulation examples and a real-time experiment are provided to illustrate the practical appeal of the proposed method.

Multiloop PID controllers tuning for desired closed loop responses

A tuning method of multiloop PID controllers is developed based on the generalized IMC PID tuning rule by Lee et al. (1998a). To extend the SISO PID tuning method to MIMO systems, a new tuning criterion is proposed. The criterion is based on the closed loop frequency response method to meet desired performance and robustness as close as possible. Examples for 2×2, 3×3 and 4×4 systems are used to illustrate the proposed method. The results show that the proposed method is superior to the conventional methods such as the BLT tuning method.

Time-domain based design and analysis of new PID tuning rules

The time domain PID analysis includes three types of first-order plus time delay (FOPTD) models: (a) zero or negligible time delay (b) low to medium long time delay and (c) very long time delay. The first part of the analysis proves that the optimum PID controller for plants having negligible time delay is a PI controller, and the corresponding PI terms based on the actuator's capacity and set-point overshoot are explicitly derived. For low to medium time delay problems, a new PID tuning scheme is then developed. The proposed tuning rule is capable of accommodating the actuator's saturation and therefore has the ability to select an optimum PID controller. By using a separate time response analysis, a new PI tuning scheme for large normalised time delay is then derived. Numerical studies are made for higher-order processes having monotonic open-loop characteristics. The performance is compared with other commonly available tuning rules. With new tuning rules, better performance is observed and the rules have the capability to cover time delays ranging from zero to any higher value.

PIDtuneTM: A Graphical Package for Integrated System Identification and PID Controller Design

This paper describes pIDtuneTM; a MATLAB-based package that integrates system identification and PID controller design. The program addresses the PID tuning needs commonly expressed by control engineers in the process industries. The package relies on ARX estimation and control-relevant model reduction to obtain models consistent with the Internal Model Control (IMC) PID tuning rules. Furthermore, the package allows the user to simulate closed-loop behavior and provides analysis tools for assessing the benefits of choosing particular tuning parameters for setpoint tracking and load disturbances, with or without uncertainty.

A General Approach to PID Optimal Design: Achievable Designs and Generation of Stabilizing Controllers

The use of optimization is an alternative to the automatic PID tuning rules based on the process reaction curve. However in order for the optimization problem to be well posed it must guarantee the stability of the resulting closed loop. A framework for PID parameter optimization with stability guarantees is what is to be proposed in this paper. The way to the solution is based on the characterization of the set of PID achievable designs and to stablish a condition that will ensure us to move on the appropriate subset of achievable stable PID designs.

Optimal-tuning PID controller design in the frequency domain with application to a rotary hydraulic system

In this paper a new PID controller design scheme that uses optimisation in the frequency domain is proposed for industrial process control. An optimal-tuning PID controller is designed to satisfy a set of frequency-domain performance requirements: gain margin, phase margin, crossover frequency and steady-state error. Using an estimated process frequency response, the method can provide optimal PID parameters even in cases where the process dynamics are time variant. This scheme is demonstrated through its application to a rotary hydraulic system and its performance is compared with six alternative PID tuning rules.

Robust PID tuning for Smith predictor in the presence of model uncertainty

Abstract This paper presents robust PID tuning for the Smith predictor in the presence of model uncertainty. The concept of the equivalent gain plus time delay (EGPTD) is introduced to incorporate robust stability in PID tuning of the Smith predictor. In particular, an application is developed for the robust tuning of the first order plus time delay (FOPTD) system and the second order plus time delay (SOPTD) system because the systems have been used extensively to describe chemical processes. The proposed tuning method can cope with simultaneous uncertainties in all parameters of the model in an efficient manner. Another important and attractive feature of the method is that it can utilize many currently available PID tuning rules. Simulation results are provided to demonstrate the availability of the method.

PID tuning based on loop-shaping H∞ control

Loop-shaping H∞ controllers are designed for both stable and integrating processes. H∞ controllers for typical industrial processes have a PID structure interpretation. Further, if the precompensator is carefully chosen, the design indicator will be independent of plant constants. This fact leads to the derivation of a direct relation between the controller parameters and the plant constants, and the results can be viewed as new PID tuning rules for stable and integrating processes. The main contribution of the tuning rules is that the PID parameters can be obtained using one design parameter which reflects the trade-off between stability robustness and time domain performance of the closed-loop system, thus making it convenient to choose PID parameters dependent on the uncertainties of the processes.

Analysis and Development of New PID Controller Tuning Rules For First-Order Processes

Abstract This paper provides the complete analysis of cascade PID controller for first-order processes. Plants with and without time delay are separately analyzed. The analysis proves the optimum selection for the plants without time delay is a PI controller with zero derivative action. New relationships are established to estimate the closed-loop ultimate gain and ultimate period for the plants with time delay. The novel PID tuning rules have been established for plants with time delay. The new criteria has the ability to select optimum gain parameters and avoid the integral windup problem. The selection of PI and PID controllers for those plants is also defined based on the actuator saturation. Simulation results revealed better performance of the proposed tuning rules compared to other commonly available tuning rules.

Tuning PID controllers for integrating processes

The paper extends the frequency domain PID controller design method, first proposed by the authors in an earlier paper, by presenting a comprehensive treatment of integrating processes. The general class of integrating processes is divided into two types, based on the sign of the second coefficient of the Taylor-series expansion applied to the stable part of the process transfer function. In both cases, the closed-loop performance is specified in terms of the desired control-signal trajectory scaled with respect to the magnitude of this coefficient. In addition, explicit PID tuning rules are given, for integrating plus delay processes along with their associated gain and phase margins and allowable time delay variations.

ASUtune: A Program for Integrated System Identification and PID Controller Design

This paper describes ASUtune , a MATLAB program for combined identification and PID controller design. By integrating identification with PID controller design, the method displays functionality that is often demanded by the practicing engineering community. The major steps in this integrated methodology are, experimental design and execution, high-order ARX estimation, and control-relevant model reduction leading to models that comply with the IMC-PID tuning rules. These PID tuning rules are compatible with the Honeywell TDC 3000 distributed control system.

Digital PID controller design using ARX estimation

This paper describes a comprehensive methodology to obtain reduced-order models that satisfy the Prett-Garcia digital PID tuning rules, using prefiltered AutoRegressive with eXternal input (ARX) estimation as a basis. The Prett-Garcia tuning rules possess the advantage that they systematically relate all the controller parameters to the plant model and a low-pass filter with a single adjustable parameter, which directly influences the closed-loop speed-of-response. Furthermore, these rules avoid the problems of intersample rippling, excessive overshoot and undershoot that are a consequence of sampling. The essential aspect of the estimation method is the selection of the prefilter, which allows the reduced model to retain those plant characteristics that have the most effect on closed-loop system behavior. The design of the prefilter is performed systematically using the engineer's desired control requirements and the setpoint/disturbance characteristics of the problem. The benefits of this method are shown for a variety of simulated plants, which include a fourth-order system, plants with time delay and integrators, and a plant with zeros outside the unit circle.