Design of VRFT Based Feedback-feedforward Controllers for Enhancing Disturbance Rejection on Non-minimum Phase Systems

2020 ◽  
Vol 15 (2) ◽  
Author(s):  
Suresh Kumar Chiluka ◽  
A. Seshagiri Rao ◽  
Murali Mohan Seepana ◽  
G. Uday Bhaskar Babu
Keyword(s):  
Disturbance Rejection ◽  
Absolute Error ◽  
Open Loop ◽  
Minimum Phase ◽  
Performance Indices ◽  
Virtual Reference ◽  
Point Tracking ◽  
Controller Performance ◽  
Feedforward Controller ◽  
Phase Systems

AbstractIn this work, Virtual Reference Feedback Tuning (VRFT) based feedback-feedforward controllers are designed for non-minimum phase systems to enhance the disturbance rejection. In model based design methods the feedforward controller is inverse of the plant model reduces the controller performance in the presence of uncertainties. The novelty of the work lies in to design VRFT based controllers independently for the feedforward structure, which decouples set point tracking and disturbance rejection. The optimal filter selection and algorithms to design the controllers were proposed with non-measurable disturbance signal using open loop experimental data. These controllers are applied to discrete time non-minimum phase Flexible Transmission System (FTS) with no load, half load and full load conditions. The simulation study on FTS with feedback and feedback plus feedforward structures evaluates the effectiveness of proposed controllers. The performance indices like Integral Absolute Error (IAE), Integral Square Error (ISE), Total Variance (TV), VRFT Objective Function (JVR) and Fragility Index (FI) are used to compare the controller’s performance. The simulation results indicate that proposed feedback plus feedforward controller is superior to feedback controller.

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.

An enhanced feedback-feedforward control scheme for process industries

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Manish Yadav ◽  
Hirenkumar G. Patel
Keyword(s):  
Transfer Function ◽  
Disturbance Rejection ◽  
Dead Time ◽  
Feedforward Control ◽  
Absolute Error ◽  
Industrial Applications ◽  
Process Industries ◽  
Control Scheme ◽  
Feedforward Controller ◽  
Bode’S Ideal Transfer Function

Abstract In this article, a unified control scheme is proposed for dead-time compensation and disturbance rejection via feedback and feedforward controller. The objectives of this work are suggested in two folds, first tuning of fractional order feedback controller via delayed Bode’s ideal transfer function instead of conventional Bode’s ideal transfer function with the benefits of dead time compensator and second feedforward controller for disturbance rejection. An existing method is utilized for comparison with the proposed scheme. To examine the efficacy of the proposed method robustness test is also carried out via sensitivity analysis. For quantifiable evaluation of the proposed scheme Integral Absolute Error (IAE) and Integral Square Error (ISE) are utilized. For the usefulness of the proposed scheme, two practical problems are demonstrated in this paper. The limpidity and instinctive appeal of the proposed scheme make it beautiful for industrial applications.

Enhanced PID Controller for Non-Minimum Phase Second Order Plus Time Delay System

2019 ◽  
Vol 14 (3) ◽  
Author(s):  
Purushottam Patil ◽  
C. Sankar Rao
Keyword(s):  
Time Delay ◽  
Closed Loop ◽  
Linear Equations ◽  
Uncertain System ◽  
Absolute Error ◽  
Delay System ◽  
Second Order ◽  
Delay Systems ◽  
Minimum Phase ◽  
Point Tracking

Abstract A tuning method is developed for the stabilization of the non-minimum phase second order plus time delay systems. It is well known that the presence of positive zeros pose fundamental limitations on the achievable control performance. In the present method, the coefficients of corresponding powers of s, s2 and s3 in the numerator are equated to α, β and γ times those of the denominator of the closed-loop system. The method gives three simple linear equations to get the PID parameter. The optimal tuning parameters α, β and γ are estimated by minimizing the Integral Time weighted Absolute Error (ITAE) for servo problem using fminsearch MATLAB solver aimed at providing lower maximum sensitivity function and keeping in check with the stability. The performance under model uncertainty is also analysed considering perturbation in one model parameter at a time using Kharitonov’s theorem. The closed loop performance of the proposed method is compared with the methods reported in the literature. It is observed that the proposed method successfully stabilizes and improves the performance of the uncertain system under consideration. The simulation results of three case studies show that the proposed method provides enhanced performance for the set-point tracking and disturbance rejection with improved time domain specifications.

Sign in / Sign up

Export Citation Format

Share Document