scholarly journals Stabilization of Unstable Second-Order Delay Plants under PID Control: A Nyquist Curve Analysis

Actuators ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 227
Author(s):  
Li Sun ◽  
Dan Ma
Keyword(s):  
Control Systems ◽  
Pid Control ◽  
Time Delays ◽  
Closed Loop ◽  
Second Order ◽  
Control Algorithms ◽  
Special Cases ◽  
Communication Links ◽  
Nyquist Stability ◽  
Real Poles

Time delays arise in various components of control systems, including actuators, sensors, control algorithms, and communication links. If not properly taken into consideration, time delays will degrade the closed-loop performance and may even result in instability. This paper studies the stabilization problem of the second-order delay plants with two unstable real poles. Stabilization conditions under PD and PID control are derived using the Nyquist stability criterion. Algorithms for computing feasible PD and PID parameter regions are proposed. In some special cases, the maximal range of delay for stabilization under PD control is also given.

Analysis of Reset Control Systems Consisting of a FORE and Second-Order Loop1

2001 ◽  
Vol 123 (2) ◽  
pp. 279-283 ◽  
Author(s):  
Qian Chen ◽  
Yossi Chait ◽  
C. V. Hollot
Keyword(s):  
Control Systems ◽  
Closed Loop ◽  
Second Order ◽  
Step Response ◽  
Steady State Response ◽  
First Order ◽  
State Response ◽  
Loop Transfer Function ◽  
Performance Specifications ◽  
Reset Control

Reset controllers consist of two parts—a linear compensator and a reset element. The linear compensator is designed, in the usual ways, to meet all closed-loop performance specifications while relaxing the overshoot constraint. Then, the reset element is chosen to meet this remaining step-response specification. In this paper, we consider the case when such linear compensation results in a second-order (loop) transfer function and where a first-order reset element (FORE) is employed. We analyze the closed-loop reset control system addressing performance issues such as stability, steady-state response, and transient performance.

Two Degree of Freedom Model Driven PID Control for Unstable Process with Time Delays

2013 ◽  
Vol 339 ◽  
pp. 45-49
Author(s):  
Li Xiang Zhang
Keyword(s):  
Control System ◽  
Control Systems ◽  
Pid Control ◽  
Time Delays ◽  
Degree Of Freedom ◽  
Control Technology ◽  
Model Driven ◽  
Unstable Process ◽  
Unstable Processes ◽  
Two Degree Of Freedom

PID control systems are the most commonly used control technology in industries. However, there are issues on control performances for the unstable process with time delays. In order to improve the control performances of PID control systems, a new two degree of freedom model driven PID control system is introduced in this paper and it is used to the unstable processes with time delay. The model driven PID control is capable of stabilizing with unstable processes by using PD feedback, regulating quickly for disturbance and tracking quickly to the change of set point. With case studies comparing with conventional PID control systems was done.

STABILIZING NETWORKED PNEUMATIC CONTROL SYSTEMS WITH TIME DELAYS

2009 ◽  
Vol 08 (02) ◽  
pp. 209-223
Author(s):  
MING-WEI HONG ◽  
CHUN-LIANG LIN ◽  
BING-MIN SHIU ◽  
NABIL AOUF
Keyword(s):  
Control Systems ◽  
Time Delays ◽  
Closed Loop ◽  
Networked Control Systems ◽  
Phase Lag ◽  
Communication Delays ◽  
Robust Controller ◽  
Loop Control ◽  
Pneumatic Control ◽  
Pid Neural Network

It has been known that time delays may not only degrade the performance of the closed-loop control systems, but also induce instability due to the introduction of extra phase lag. The focus of this paper is to find out a way to design a robust controller for networked control systems (NCSs) with time-varying communication delays. To this aim, a mixed fuzzy-PID/neural network compensating scheme is proposed so as to alleviate the influence resulting from uncertain communication delays while maintaining system performance. A condition ensuring stability of the NCS is derived from the system's input–output viewpoint. The effectiveness and superiority of our proposed approach are fully verified in an experimentally networked pneumatic control system.

Enhanced Dynamic Set-point Weighting Design for Two-Input-Two-Output (TITO) Unstable Processes

2019 ◽  
Vol 15 (1) ◽  
Author(s):  
Purushottama Rao Dasari ◽  
A. Seshagiri Rao
Keyword(s):  
Pid Control ◽  
Time Delays ◽  
Closed Loop ◽  
Control Law ◽  
Unstable Systems ◽  
Set Point ◽  
Point Tracking ◽  
Unstable Processes ◽  
Tito Systems ◽  
Independent Loops

Abstract Control of unstable systems with time delays usually result in overshoots in the closed loop responses. The intricacy involved in multivariable unstable processes further makes the problem more challenging. In industry, set-point weighting is one of the recommended methods to minimize the overshoot. However, design of the set-point weighting parameters determines the percentage of minimization of the overshoot. In this paper, a method is proposed to design the set-point weighting parameters for unstable multivariable processes which is relatively simple and also reduces the overshoot. Weighting is considered for both proportional (β) and derivative (γ) terms in the PID control law. In the closed loop relation for set-point tracking, the coefficients of ‘s’ and ‘s3’ both in the numerator and denominator are made equal in order to find dynamically β and γ. The obtained expressions for β and γ are simple and dynamically depends on the controller parameters and are applied to TITO systems in present work. Decouplers are used in TITO systems mainly to reduce the interaction between the loops so that they can be viewed as independent loops. Decoupler design suggested by (Hazarika and Chidambaram [1] has been used in this work and two TITO unstable processes with time delays are illustrated here. Comparison with the reported methods available in literature verifies that the proposed method gives improved closed loop performance.

scholarly journals Development of a Sucker Rod Pumping Unit Simulation Model

2019 ◽  
Vol 9 (1) ◽  
pp. 4403-4409
Keyword(s):  
Simulation Model ◽  
Control Systems ◽  
Closed Loop ◽  
Control Algorithms ◽  
Oil Reservoir ◽  
Closed Loop System ◽  
Optimal Control Algorithms ◽  
Sucker Rod ◽  
Pumping Unit ◽  
And Control

In this paper a process of development of sucker rod pumping unit (SRPU) simulation model with “oil reservoir-well” and control systems is presented. In this paper is presented process of development of sucker rod pumping unit (SRPU) simulation model with “oil reservoir-well” and control systems. The developed model describes the SRPU blocks for oil production in detail, allows studying the system with various equipment and well parameters and provides the logic of the closed loop system. It becomes possible to develop optimal control algorithms based on obtained dependencies. The results of simulation of operation and sucker rod pump (SRP) faults are given.

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