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Feedback Control Design
Published in Jose A. Romagnoli, Ahmet Palazoglu, Introduction to Process Control, 2020
Jose A. Romagnoli, Ahmet Palazoglu
This method is based on the following premises: The controller design requires a process model and a desired closed-loop transfer function (one with desired dynamic characteristics).The desired closed-loop transfer function is usually specified for set-point changes, but responses to disturbances can also be utilized.Although these controllers do not always have a PID structure, the direct synthesis (DS) method does produce PI or PID controllers for common process models (e.g., FOPDT and SOPDT).
Controller Tuning
Published in Raghunathan Rengaswamy, Babji Srinivasan, Nirav Pravinbhai Bhatt, Process Control Fundamentals, 2020
Raghunathan Rengaswamy, Babji Srinivasan, Nirav Pravinbhai Bhatt
In contrast to Z-N tuning, where we started from stability considerations, in direct synthesis, we directly start with a closed-loop performance that we desire. We ensure stability by choosing a closed-loop transfer function that is stable. Now, the transfer function of the controller is directly synthesized based on the desired closed-loop transfer function. We will see that this seemingly simple idea is very powerful and can be used to understand several important control ideas. There is also another difference between Z-N and direct synthesis tuning. In Z-N approach, the tuning is for PID controllers. In contrast, in the D-S approach, we do not start with a structure and a controller TF is a result of the design procedure. In many cases, this TF turns out to be of the PID form with a filter.
Stability Tests
Published in William S. Levine, Control System Fundamentals, 2019
Robert H. Bishop, Richard C. Dorf, Charles E. Rohrs, Mohamed Mansour, Raymond T. Stefani
In terms of linear systems, we recognize that the stability requirement may be defined in terms of the location of the poles of the closed-loop transfer function. Consider a single-input, single-output closed-loop system transfer function given by () T(s)=p(s)q(s)=K∏i=1M(s+zi)∏k=1Q(s+σk)∏m=1R(s2+2αms+αm2+ωm2),
Robust Passive Fault Tolerant Control for Air Fuel Ratio Control of Internal Combustion Gasoline Engine for Sensor and Actuator Faults
Published in IETE Journal of Research, 2023
Arslan Ahmed Amin, Khalid Mahmood-ul-Hasan
The stability analysis of the proposed PFTCS has been carried out in MATLAB by determining the location of poles of the closed-loop system. Linear control analysis and pole-zero plot techniques of MATLAB, as described in [44,45] have been utilized for this purpose. According to Lyaponuv's first stability criterion for the linear systems, the poles of the closed-loop transfer function of a stable system must lie in the left half complex plane [46]. The pole-zero map of our PFTCS controller is shown in Figure 17.
Evaluation of nonlinear control performance of air handling units under variable operation conditions using root distribution approach
Published in Science and Technology for the Built Environment, 2022
Zufen Wang, Rodney Hurt, Choon Yik Tang, Li Song, Gang Wang
For a linear time-invariant (LTI) feedback control system, the Laplace transform of its output can be expressed as the product of the Laplace transform of its input, which can be either a reference input or a disturbance input, and its closed-loop transfer function. The closed-loop poles, defined as the roots of the characteristic equation of the closed-loop transfer function, can give valuable insight into the control performance, such as whether the system is stable, oscillatory, sluggish, and aggressive.
Wheelset curving guidance using H∞ control
Published in Vehicle System Dynamics, 2018
Alireza Qazizadeh, Sebastian Stichel, Hamid Reza Feyzmahdavian
In this study it is shown how to design a controller for wheelset steering in curves. The controller is designed based on closed-loop transfer function shaping and optimisation. The controller is designed for both nominal and uncertain plants and both stability and performance are checked.