New simple controller tuning rules for integrating and stable or unstable first order plus dead-time processes (original) (raw)
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Archives of Control Sciences, 2021
The time delay element present in the PI controller brings dead-time compensation capability and shows improved performance for dead-time processes. However, design of robust time delayed PI controller needs much responsiveness for uncertainty in dead-time processes. Hence in this paper, robustness of time delayed PI controller has been analyzed for First Order plus Dead-Time (FOPDT) process model. The process having dead-time greater than three times of time constant is very sensitive to dead-time variation. A first order filter is introduced to ensure robustness. Furthermore, integral time constant of time delayed PI controller is modified to attain better regulatory performance for the lag-dominant processes. The FOPDT process models are classified into dead-time/lag dominated on the basis of dead-time to time constant ratio. A unified tuning method is developed for processes with a number of dead-time to time constant ratio. Several simulation examples and experimental evaluation are exhibited to show the efficiency of the proposed unified tuning technique. The applicability to the process models other than FOPDT such as high-order, integrating, right half plane zero systems are also demonstrated via simulation examples.
Simple Tuning Rules of PID Controllers for Integrator/Dead time Processes
In this paper, simple rules for tuning PID controllers for integrator/dead time processes are proposed. These rules are derived by the optimization of a discrete-time error integral criterion called the switch time weighted summation of squared error (SWSSE) criterion. In this criterion, the first M samples of the transient response are weighted by 1, while the remaining samples until the end of the response are heavily weighted by e.g. 10 4 . The instant, M, of applying the large weight affects the characteristics of the response. By choosing M that achieves the minimum possible settling time, it is found that the optimal controller for servo problem is PD, while for regulatory problem it is PID. To get a single set of rules, a two-degree of freedom (2DOF) controller is then proposed, in which the PID settings for load disturbance rejection is used in addition to a first-order set-point filter to improve the set-point response. The proposed rules achieve good settling time, nearly no overshoot, fast load disturbance rejection and fair control effort. The robustness of the proposed method is quite acceptable.
… Conference on Control …, 2003
In this paper, the use of the Pseudo-Derivative Feedback (PDF) structure in the control of integrating plus deadtime (IPDT) processes is investigated. Simple methods for tuning the PDF feedback controller are presented. The PDF control structure and the proposed tuning methods ensure smooth closed-loop response to set-point changes, fast regulatory control and sufficient robustness against parametric uncertainty. The proposed methods require small computation effort and they are particularly useful for on-line applications, since they require prior information that can easily be obtained using the relay autotuning method. Simulation results show that our methods are favorably compared to the already known PI/PID controller tuning methods for IPDT processes.
… IEEE Transactions on, 2006
The control of unstable first-order plus dead-time (UFOPDT) processes using proportional-integral (PI) and proportional-integral-differential (PID) type controllers is investigated in this brief. New tuning rules based on the exact satisfaction of gain and phase margin specifications are proposed. The tuning rules are given in the form of iterative algorithms, as well as in the form of accurate, analytical approximations. Moreover, several specific functions, related to the crossover frequencies of the Nyquist plot and to the feasible design specifications for a given process, are derived. These functions, which are particularly useful for the general design of PI-and PID-type controllers for UFOPDT processes are accurately approximated, in order to simplify the tuning procedure. With the proposed approximations, the tuning rules reported in this brief require relatively small computational effort and are particularly useful for online applications.
A simple method of tuning PID controller for Integrating First Order Plus time Delay Process
2016
A simple method is proposed to design a PID controller for Integrating First Order Plus Time Delay system. Design is simple compared to the other tuning methods. It has been proposed for the pneumatic control system based on the method of gain scheduling. The performance of the controller is measured by the simulation and it is compared with the other two tuning methods which is Skogested [1] and Shinskey [2]. Simulation results shows that the proposed method has lesser error ISE and IAE than the other two methods. Disturbance rejection is also good in the proposed method. INTRODUCTION PID controller design based on stability analysis, constant open loop transfer function, pole placement method, stable inverse of the model and direct synthesis method has been proposed. In all the above methods the design procedure is somewhat complicated. A simple method is proposed for First Order Plus Time Delay system by using the method of gain scheduling [3]. But PID controller for Integrating ...
IFAC-PapersOnLine, 2018
This paper proposes a method so that all PID controller tuning parameters, which are satisfying stability of any integrating time delay processes, can be calculated by forming the stability boundary loci. Processes having a higher order transfer function must first be modeled by an integrating plus first order plus dead time (IFOPDT) transfer function in order to apply the method. Later, IFOPDT process transfer function and the controller transfer function are converted to normalized forms to obtain the stability boundary locus in 2 , (/)
Closed-Loop PI/PID Controller Tuning for Stable and Integrating Process with Time Delay
The objective of this study is to develop a new online controller tuning method in closed-loop mode. The proposed closed-loop tuning method overcomes the shortcoming of the well-known Ziegler-Nichols (1942) continuous cycling method and it can be an alternative for the same. This is a simple method to obtain the PI/PID setting which gives the acceptable performance and robustness for a broad range of the processes. The method requires a closed-loop step set-point experiment using a proportional only controller with gain Kc0. On the basis of simulations for a range of first-order with time delay processes, simple correlations have been derived to give PI/PID controller settings. The controller gain (Kc/Kc0) is only a function of the overshoot observed in the set-point experiment. The controller integral and derivative time (τI and τD) is mainly a function of the time to reach the first peak (tp). The simulation has been conducted for a broad class of stable and integrating processes, and the results are compared with a recently published paper of Shamsuzzoha and Skogestad (2010).1 The proposed tuning method gives consistently better performance and robustness for a broad class of processes.
Tuning PID Controllers for Time-Delay Processes with Maximizing the Degree of Stability
In this paper, we propose a method of tuning PID controller parameters for first-order plus dead-time processes with the objective of maximizing the degree of stability. Since the presence of dead-time in a feedback loop gives rise to an infinite-dimensional closed-loop system, which has an infinite number of poles and thus the conventional Routh-Hurwitz algebraic criterion of stability cannot be applied to characterize the necessary conditions of the maximum degree of stability. To overcome this difficulty, we make use the theory of D-partition technique. Based on analytically characterizing the D-partition boundaries of the controller parameter space, necessary conditions of the maximum degree of stability are derived. With these derived conditions, the problem of maximizing the degree of stability is converted to a set of parametric optimization problems, whose solutions can be obtained by an existing method. For showing the applicability of the method, a tuning example with graphical illustrations is given.
International Journal of Automation and Control, 2019
This work proposes the coefficient diagram method (CDM)-based two degree of freedom proportional integral (CDM-PI) controller tuning rules for stable and unstable first order plus time delay (FOPTD) processes and pure integrating processes with time delay (PIPTD). To derive the tuning rules, a general first order plus time delay (FOPTD) model, the first order Taylor denominator (TD) approximation technique and the pole allocation strategy named CDM is used. The tuning rules derived here are novel and they relate the controller parameters to the process model parameters directly. The performance of the CDM-PI controller utilising the proposed tuning rules is tested with numerical examples of stable, unstable and pure integrating processes with time delay models. The test results indicate that the proposed tuning rules yield promising results over the other PI controllers. Performance measures confirm the effectiveness of the proposed tuning method.