Analytical Design for Parallel Cascade Control of Multiple Degrees of Freedom

2010 ◽  
Vol 44-47 ◽  
pp. 1417-1421
Author(s):  
Cheng Qiang Yin ◽  
Jie Gao ◽  
Hong Tao Wang
Keyword(s):  
Disturbance Rejection ◽  
Degrees Of Freedom ◽  
Control Program ◽  
Smith Predictor ◽  
Cascade Control ◽  
Primary Loop ◽  
Set Point ◽  
Multiple Degrees Of Freedom ◽  
Point Tracking ◽  
Cascade Processes

A new parallel cascade control program of multiple degrees of freedom is proposed for chemical and industrial cascade processes. Firstly, the two degree of freedom IMC structure is adopted in the secondary control loop, and the set-point tracking and disturbance rejection are decoupled, therefore, the influence on performance of primary loop because of the coupling between the set-point tracking and disturbance rejection in the secondary loop is reduced. Then, based on a modified structure of the Smith predictor control, the primary loop realizes the decoupling control between set-point tracking and disturbance rejection, and simple and effective analytical method is adopted to devise the controllers. Finally, simulations example demonstrates the validity of the proposed control scheme.

scholarly journals Enhanced PID Controllers Design Based on Modified Smith Predictor Control for Unstable Process with Time Delay

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Chengqiang Yin ◽  
Jie Gao ◽  
Qun Sun
Keyword(s):  
Time Delay ◽  
Disturbance Rejection ◽  
Direct Synthesis ◽  
Synthesis Method ◽  
Engineering Application ◽  
Smith Predictor ◽  
Superior Performance ◽  
Set Point ◽  
Point Tracking ◽  
Modified Smith Predictor

A two-degree-of-freedom control structure is proposed for a class of unstable processes with time delay based on modified Smith predictor control; the superior performance of disturbance rejection and good robust stability are gained for the system. The set-point tracking controller is designed using the direct synthesis method; the IMC-PID controller for disturbance rejection is designed based on the internal mode control design principle. The controller for set-point response and the controller for disturbance rejection can be adjusted and optimized independently. Meanwhile, the two controllers are designed in the form of PID, which is convenient for engineering application. Finally, simulation examples demonstrate the validity of the proposed control scheme.

scholarly journals A Modified 2-DOF Control Framework and GA Based Intelligent Tuning of PID Controllers

Processes ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 423
Author(s):  
Gun-Baek So
Keyword(s):  
Disturbance Rejection ◽  
Pid Controller ◽  
Weighting Function ◽  
Pid Controllers ◽  
Set Point ◽  
Tuning Method ◽  
Point Tracking ◽  
Load Disturbance ◽  
Control Framework ◽  
Feedforward Controller

Although a controller is well-tuned for set-point tracking, it shows poor control results for load disturbance rejection and vice versa. In this paper, a modified two-degree-of-freedom (2-DOF) control framework to solve this problem is proposed, and an optimal tuning method for the pa-rameters of each proportional integral derivative (PID) controller is discussed. The unique feature of the proposed scheme is that a feedforward controller is embedded in the parallel control structure to improve set-point tracking performance. This feedforward controller and the standard PID con-troller are combined to create a new set-point weighted PID controller with a set-point weighting function. Therefore, in this study, two controllers are used: a set-point weighted PID controller for set-point tracking and a conventional PID controller for load disturbance rejection. The parameters included in the two controllers are tuned separately to improve set-point tracking and load dis-turbance rejection performances, respectively. Each controller is optimally tuned by genetic algo-rithm (GA) in terms of minimizing the IAE performance index, and what is special at this time is that it also tunes the set-point weighting parameter simultaneously. The simulation results performed on four virtual processes verify that the proposed method shows better performance in set-point tracking and load disturbance rejection than those of the other methods.

scholarly journals PID Controller Design for TITO Processes Based on IMC and Smith Predictor Configuration

2019 ◽  
Vol 8 (6S4) ◽  
pp. 1522-1526
Keyword(s):  
Time Delay ◽  
Disturbance Rejection ◽  
Pid Controller ◽  
Controller Design ◽  
Control Design ◽  
Smith Predictor ◽  
Point Tracking ◽  
Pid Controller Design ◽  
Reduced Time

This paper describes the design of ProportionalIntegral-Derivative (PID) controller for two variable processes where the two variables need to control. Design of controllers for such a process is too difficult than single variable processes because of interrelations between the two variables present in the system. Hence, the design approach should include the interrelations of the variables to achieve better performance of the processes. In addition to this, the time delay of the processes is also considered and Smith Predictor (SP) configuration is used to reduce the delay in the processes. For the resultant reduced time delay processes, an IMC approach is used to design PID controller. The proposed control system improves both the servo (set point tracking) and regulatory (disturbance rejection) performance of the system. The proposed configuration is also validated using a case study. The simulation results are presented and compared with the other similar approaches to show the efficacy of the proposed method

Cascade control strategy for external carbon dosage in predenitrifying process

2002 ◽  
Vol 45 (4-5) ◽  
pp. 53-60 ◽  
Author(s):  
J.-H. Cho ◽  
S.W. Sung ◽  
I.-B. Lee
Keyword(s):  
Control Strategy ◽  
Disturbance Rejection ◽  
Nitrate Concentration ◽  
Cascade Control ◽  
Control Loop ◽  
Relay Feedback ◽  
Point Tracking ◽  
Pi Controllers ◽  
Good Set

We propose a cascade control strategy composed of two Proportional-Integral (PI) controllers to regulate the nitrate concentration in the predenitrifying process by manipulating the external carbon dosage. It controls the nitrate concentrations in the effluent as well as in the final anoxic reactor simultaneously to strictly satisfy the quality of the effluent as well as to remove the effects of disturbances more quickly. The design of two PI controllers in the cascade control loop can be completed with the Ziegler–Nichols (Z–N) tuning rule together with a simple relay feedback identification method. Results from the Benchmark simulation confirm that both good set point tracking and satisfactory disturbance rejection can be guaranteed due to the structural advantages of the proposed cascade control strategy. Also, compared with a previous work, the fluctuation of the nitrate concentration in the effluent has been decreased significantly.

Extended state observer based fractional order controller design for integer high order systems

2021 ◽  
pp. 095440622110621
Author(s):  
Rachid Mansouri ◽  
Maamar Bettayeb ◽  
Ubaid M Al-Saggaf ◽  
Abdulrahman U Alsaggaf ◽  
Muhammad Moinuddin
Keyword(s):  
Fractional Order ◽  
Disturbance Rejection ◽  
State Observer ◽  
Internal Model Control ◽  
Extended State Observer ◽  
Extended State ◽  
Set Point ◽  
Point Tracking ◽  
Model Control ◽  
Fractional Order Controller

In this paper, based on the extended state observer (ESO) and on a fractional order controller (FOC), composed of an integer order PID cascaded with a fractional order filter (FOF), a new control scheme for an n th order integer plant is proposed. The ESO is used to estimate and cancel the unknown internal dynamics and the external disturbance. Afterwards, an FOC is designed to resolve the set-point tracking problem. An analytical and systematic method is proposed to design the FOC. This method is based on the Internal Model Control (IMC) and the Bode’s Ideal Transfer Function (BITF). Therefore, the proposed control structure improves the robustness and performance of the traditional linear active disturbance rejection control (LADRC), especially for the open-loop gain variation. In addition, since the system be controlled is an n th order, a general form of the BITF is also proposed. Numerical simulations on a nonlinear model and experimental results on a cart-pendulum system design illustrate the effectiveness of the suggested ESO-PID-FOF scheme for the disturbance rejection, the set-point tracking and robustness. A comparison with the results obtained using the standard LADRC is also presented.

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