scholarly journals A Novel Design of Fractional PI/PID Controllers for Two-Input-Two-Output Processes

2019 ◽  
Vol 9 (23) ◽  
pp. 5262 ◽  
Author(s):  
Chuong ◽  
Vu ◽  
Truong ◽  
Jung

In this paper, a new formulation of fractional order proportional integral (PI)/ proportional integral derivative (PID) controller is proposed. The proposed controller will be justified for some well-known two-input-two-output (TITO) processes. In order to deal with interactions between process variables in a multivariable system, as well as multiple delay times in process transfer functions, the simplified decoupling Smith predictor (SDSP) structure is also used. The issue of decoupling realizability is solved by the PSO algorithm and fractional order processes are also suggested for model reduction. The tuning rules of the controller are derived in analytical terms based on the internal model control (IMC) structure. The effectiveness and robust stability of the proposed approach are illustrated by comparing it with other methods. To have a fair comparison, the robustness criterion using the M-Δ structure with μ-synthesis is adopted and the μ value of the proposed method is always kept smaller than the value of the others.

Author(s):  
Kahina Titouche ◽  
Rachid Mansouri ◽  
Maamar Bettayeb ◽  
Ubaid M. Al-Saggaf

An analytical design for proportional integral derivative (PID) controller cascaded with a fractional-order filter is proposed for first-order unstable processes with time delay. The design algorithm is based on the internal model control (IMC) paradigm. A two degrees-of-freedom (2DOF) control structure is used to improve the performance of the closed-loop system. In the 2DOF control structure, an integer order controller is used to stabilize the inner-loop, and a fractional-order controller for the stabilized system is employed to improve the performance of the closed-loop system. The Walton–Marshall's method, which is applicable to quasi-polynomials, is then used to establish the internal stability condition of the closed-loop system (the fractional part of the controller in particular) and to seek the set of stabilizing proportional (P) or proportional-derivative (PD) controller parameters.


Author(s):  
Tassadit Chekari ◽  
Rachid Mansouri ◽  
Maamar Bettayeb

The coupled tanks process is a two input-two output system. It presents a nonlinear behavior and interactions characteristic. After the nonlinear model is obtained, it is linearized around an operating point. A fractional-order proportional–integral–derivative based on the internal model control paradigm (1DOF-IMC-PID-FO) multi-loop controller is determined without considering the interactions, and a fractional-order proportional–integral–derivative based on the 2-degree-of-freedom internal model control structure (2DOF-IMC-PID-FO) multi-loop controller is determined by considering the interactions. Thus, an interactions reduction effect controller is calculated. Both controllers are implemented on a real-time process using the Real Time Windows Target of MATLAB. The objective of the control is to maintain the water level in the lower tanks at desired values. In the experiment, setpoint tracking and disturbance rejection tests are carried out to assess the performance of both 1DOF and 2DOF-IMC-PID-FO multi-loop controllers.


Author(s):  
Yan Ti ◽  
Kangcheng Zheng ◽  
Wanzhong Zhao ◽  
Tinglun Song

To improve handling and stability for distributed drive electric vehicles (DDEV), the study on four wheel steering (4WS) systems can improve the vehicle driving performance through enhancing the tracking capability to desired vehicle state. Most previous controllers are either a large amount of calculation, or requires a lot of experimental data, these are relatively time-consuming and laborious. According to the front and rear wheel steering angle of DDEV can be distributed independently, a novel controller named internal model controller with fractional-order filter (IMC-FOF) for 4WS systems is proposed and studied in this paper. The IMC-FOF is designed using the internal model control theory and compared with IMC and PID controller. The influence of time constant and fractional-order parameters which is optimized using quantum genetic algorithms (QGA) on tracking ability of vehicle state are also analyzed. Using a production vehicle as an example, the simulation is performed combining Matlab/Simulink and CarSim. The comparison results indicated that the proposed controller presents performance to distribute the front and rear wheel steering angle for ensuring better tracking capability to desired vehicle state, meanwhile it possesses strong robustness.


Processes ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 190
Author(s):  
Sveinung Ohrem ◽  
Håvard Skjefstad ◽  
Milan Stanko ◽  
Christian Holden

To enable more efficient production of hydrocarbons on the seabed in waters where traditional separator equipment is infeasible, the offshore oil and gas industry is leaning towards more compact separation equipment. A novel multi-pipe separator concept, designed to meet the challenges of subsea separation, has been developed at the Department of Geoscience and Petroleum at the Norwegian University of Science and Technology. In this initial study, a control structure analysis for the novel separator concept, based on step-response experiments, is presented. Proportional-integral controllers and model reference adaptive controllers are designed for the different control loops. The proportional-integral controllers are tuned based on the well-established simple internal model control tuning rules. Both control methods are implemented and tested on a prototype of the separator concept. Different measurements are controlled, and results show that the performance of the separator under varying inlet conditions can be improved with proper selection of control inputs and measurements.


2014 ◽  
Vol 573 ◽  
pp. 279-284 ◽  
Author(s):  
Neenu Elizabeth Cherian ◽  
K. Sundaravadivu

This paper presents an analytical design method for fractional order proportional integral (FOPI) controller for the spherical tank which is modelled as a first order plus dead time (FOPDT) process. The design is based on the Bode’s ideal transfer function and fractional calculus. By using frequency domain, the proposed FOPI tuning rules are directly derived for a generalized first order plus dead time process and then applied to the transfer functions obtained at various operating points of the spherical tank. The performance of the designed FOPI controller is compared with the conventional integer order proportional integral derivative (IOPID) controller in simulation.


Author(s):  
Dazi Li ◽  
Xingyu He

Many processes in the industry can be modeled as fractional order, research on the fractional order become more and more popular. Usually, controllers such as fractional order PID (FOPID) or fractional active disturbance rejection control (FADRC) are used to control single-input-single-output (SISO) fractional order system. However, when it comes to fractional order two-input-two-output (TITO) processes, few research focus on this. In this paper, a new design method for fractional order control based on multivariable non-internal model control with inverted decoupling is proposed to handle non-integer order two-input-two-output system. The controller proposed in this paper just has two parameters to tune compared with the five parameters of the FOPID controller, and the controller structure can be achieved by internal model control (IMC) method which means it is easy to implement. The parameters tuning method used in this paper is based on frequency domain strategy. Compared with integer order situation, fractional order method is more complex, because the calculation of the frequency domain characteristics is difficult. The controller proposed in this paper is robust to process gain variations, what’s more, it provides ideal performance for both set point-tracking and disturbance rejection. Numerical results are given to show the performance of the proposed controller.


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