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.

Multi-Rate Feedforward Tracking Control for Plants With Nonminimum Phase Discrete Time Models

1999 ◽  
Vol 123 (3) ◽  
pp. 556-560 ◽  
Author(s):  
Yuping Gu ◽  
Masayoshi Tomizuka
Keyword(s):  
Discrete Time ◽  
Tracking Control ◽  
Performance Enhancement ◽  
Feedforward Control ◽  
Phase Error ◽  
Sampling Rate ◽  
Time Model ◽  
Rate System ◽  
Control Scheme ◽  
Feedforward Controller

This paper is concerned with performance enhancement of tracking control systems by multi-rate control. The feedback controller is updated at the same rate as the sampling rate of the output measurements. The feedforward controller processes the desired output signal for high accuracy tracking, and its output is updated at a rate N-times faster than the sampling rate of the output measurements. The discrete time model of the controlled plant may possess unstable zeros, and the zero phase error tracking controller (ZPETC) is used as a feedforward controller. Inter-sample behavior of the plant is included in evaluating the tracking performance of the multi-rate system. Illustrative examples are given to show advantages of the proposed multi-rate feedback/feedforward control scheme.

Feedforward Input Generation Based on Neural Network Prediction in Multi-Joint Robots1

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Jonathan Asensio ◽  
Wenjie Chen ◽  
Masayoshi Tomizuka
Keyword(s):  
Neural Network ◽  
Feedforward Control ◽  
Industrial Robot ◽  
Tracking Error ◽  
Industrial Applications ◽  
Superior Performance ◽  
Control Scheme ◽  
Neural Network Prediction ◽  
Network Prediction ◽  
Learning Data

Learning feedforward control based on the available dynamic/kinematic system model and sensor information is generally effective for reducing the tracking error for a learned trajectory. For new trajectories, however, the system cannot benefit from previous learning data and it has to go through the learning process again to regain its performance. In industrial applications, this means production line has to stop for learning, and the overall productivity of the process is compromised. To solve this problem, this paper proposes a feedforward input generation scheme based on neural network (NN) prediction. Learning/training is performed for the NNs for a set of trajectories in advance. Then the feedforward torque input for any trajectory in the predefined workspace can be calculated according to the predicted error from multiple NNs managed with expert logic. Experimental study on a 6-DOF industrial robot has shown the superior performance of the proposed NN based feedforward control scheme in the position tracking as well as the residual vibration reduction, without any further learning or end-effector sensors during operation.

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.

Feedforward Control of Single-Link Flexible Manipulators by Discrete Model Inversion

1999 ◽  
Vol 121 (4) ◽  
pp. 713-721 ◽  
Author(s):  
V. Feliu ◽  
K. S. Rattan
Keyword(s):  
Transfer Function ◽  
Feedforward Control ◽  
Point Of View ◽  
Model Inversion ◽  
Single Link ◽  
Feedforward Controller ◽  
Tip Position ◽  
Flexible Arms ◽  
System Transfer Function ◽  
General Method

The design of feedforward controllers to control the position of single-link flexible arms is developed in this paper. The objective is to drive the tip position along a commanded trajectory without any oscillations at the tip. The method is based on the well-known dynamics model inversion technique. Since the controllers are implemented on a computer, the dynamic inversion of the single-link flexible arm is studied from a discrete point of view. A general method to obtain a feedforward controller is developed, even in the case when the system transfer function is of nonminimum phase. The method is general in the sense that it removes oscillation in the arm with any number of vibration modes. A method to modify the transfer function of these controllers to improve the robustness is also proposed in this paper. It is shown that the input preshaping scheme developed by Singer and Seering is a special case of this method. The design technique is illustrated with numerical examples and a comparison with the input preshaping method is carried out.

Predictor-based fractional disturbance rejection control for LTI fractional-order systems with input delay

2020 ◽  
Vol 42 (16) ◽  
pp. 3303-3319
Author(s):  
Sajad Pourali ◽  
Hamed Mojallali
Keyword(s):  
Transfer Function ◽  
Fractional Order ◽  
Disturbance Rejection ◽  
Closed Loop ◽  
Reference Model ◽  
Open Loop ◽  
Input Delay ◽  
Fractional Order Systems ◽  
Disturbance Rejection Control ◽  
Bode’S Ideal Transfer Function

In this paper, a predictor-based fractional disturbance rejection control (PFDRC) scheme is proposed for processes subject to input delay. The proposed scheme can be generally applied to open-loop stable, integrative, and unstable integer-order processes, but it can be particularly utilized for open-loop stable fractional-order systems. A closed-loop reference model is formulated based on Bode’s ideal transfer function. The primary control design objective is to enable the output of input-delay process to follow the closed-loop reference model. Towards this end, the closed-loop transfer function of the PFDRC must take the same structure as that of the reference model. Meanwhile, the adverse effects of the input delay must be mitigated. To meet the latter, a filtered Smith predictor (FSP) is employed to provide a prediction of delay-less output response. To address the former, process dynamics are treated as a common disturbance; then, a fractional-order extended state observer (FESO) is introduced to estimate the delay-less output response and also the total disturbance (i.e. external disturbance and system uncertainties). The PFDRC feedback controller is easily derived by the gain crossover frequency of Bode’s ideal transfer function which facilitates the tuning process. The convergence analysis of the FESO is carried out in terms of BIBO stability. The effectiveness of the proposed control scheme is verified through three illustrative examples from the literature.

Nonlinear Feedforward-Feedback Control of an Electric Clutch Actuator

2014 ◽  
Vol 1014 ◽  
pp. 339-343 ◽  
Author(s):  
Xin Li ◽  
Hui Zhou ◽  
Hao Li ◽  
Xue Song Li
Keyword(s):  
Feedback Control ◽  
Feedforward Control ◽  
Experimental Tests ◽  
Linear Feedback ◽  
Original Form ◽  
Model Errors ◽  
Nonlinear Characteristics ◽  
Control Scheme ◽  
Control Requirement ◽  
Feedforward Controller

For a novel electric clutch actuator, a nonlinear feedforward-feedback control scheme is proposed to improve the performance of the position tracking control. The feedforward control is designed based on flatness in consideration of the system nonlinearities, and the linear feedback control is given to accommodate the model errors and the disturbances. Lookup tables, which are used to represent nonlinear characteristics of the actuator systems, such as friction force, appear in their original form in the designed feedforward controller. The designed controller is evaluated through simulations and experimental tests, which show that the proposed controller satisfied the control requirement. Comparison with PID control is given as well.

scholarly journals Improved Position Control for an EGR Valve System with Low Control Frequency

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 457
Author(s):  
Hyeong-Jin Kim ◽  
Yung-Deug Son ◽  
Jang-Mok Kim
Keyword(s):  
Position Control ◽  
Feedforward Control ◽  
Fast Response ◽  
Control Frequency ◽  
Position Response ◽  
Control Scheme ◽  
Position Controller ◽  
Valve Position ◽  
Feedforward Controller ◽  
Gas Recirculation

An exhaust gas recirculation (EGR) valve position control system requires fast response without overshoot, but the low control frequency limits control bandwidth and results in poor position response. A novel EGR valve position control scheme is proposed to improve the position response at low control frequency. This is based on the feedforward controller, but the feedforward control loop is implemented without the position pattern generator or derivative. The proposed method estimates the acceleration command through the relationship between the position controller output, the speed command and the speed limiter, and compensates the cascaded proportional-proportional integral (P-PI) controller. In this method, many operations are not required and noise due to derivative is not generated. This method can improve the position response without much computation and derivative noise at the low control frequency. Experimental results are presented to verify the feasibility of the proposed position control algorithm.

scholarly journals Anti-Disturbance Compensation-Based Nonlinear Control for a Class of MIMO Uncertain Nonlinear Systems

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1487
Author(s):  
Wameedh Riyadh Abdul-Adheem ◽  
Ahmed Alkhayyat ◽  
Ammar K. Al Mhdawi ◽  
Nik Bessis ◽  
Ibraheem Kasim Ibraheem ◽  
...  
Keyword(s):  
Decentralized Control ◽  
Disturbance Rejection ◽  
Mimo Systems ◽  
Mimo System ◽  
Industrial Applications ◽  
Active Disturbance Rejection Control ◽  
Disturbance Compensation ◽  
Active Disturbance Rejection ◽  
Disturbance Rejection Control ◽  
Control Scheme

Multi-Inputs-Multi-Outputs (MIMO) systems are recognized mainly in industrial applications with both input and state couplings, and uncertainties. The essential principle to deal with such difficulties is to eliminate the input couplings, then estimate the remaining issues in real-time, followed by an elimination process from the input channels. These difficulties are resolved in this research paper, where a decentralized control scheme is suggested using an Improved Active Disturbance Rejection Control (IADRC) configuration. A theoretical analysis using a state-space eigenvalue test followed by numerical simulations on a general uncertain nonlinear highly coupled MIMO system validated the effectiveness of the proposed control scheme in controlling such MIMO systems. Time-domain comparisons with the Conventional Active Disturbance Rejection Control (CADRC)-based decentralizing control scheme are also included.

Adaptive Feedforward Vibration Control of Flexible Structure With Discrete Sliding Mode Controller

2006 ◽  
Author(s):  
J. Fei
Keyword(s):  
Control System ◽  
Sliding Mode Control ◽  
Sliding Mode ◽  
Feedforward Control ◽  
Flexible Beam ◽  
Sliding Mode Controller ◽  
Control Scheme ◽  
Feedforward Controller ◽  
Adaptive Lms ◽  
Adaptive Feedforward

This paper presents an adaptive feedforward control scheme using the least mean square (LMS) algorithm combined with sliding mode control for a flexible beam using piezoceramic actuator. A finite element model of the dynamic response of flexible beam system with PZT patches is derived and analyzed. Implementation of an adaptive LMS feedforward controller has the advantages of inherent stability and simplicity in design. The proposed adaptive LMS feedforward control system maintains the basic structure of the adaptive feedforward controller, but incorporates reference model in the system. Discrete sliding mode controller is added in the feedback loop to enhance the robustness of control system subjected to the variation of system parameters and external disturbances. Simulation results from flexible beam model verify the effectiveness of the proposed adaptive LMS feedforward with sliding mode control scheme and good disturbance rejection properties.

scholarly journals Fuzzy PID Feedback Control of Piezoelectric Actuator with Feedforward Compensation

2014 ◽  
Vol 2014 ◽  
pp. 1-14 ◽  
Author(s):  
Ziqiang Chi ◽  
Minping Jia ◽  
Qingsong Xu
Keyword(s):  
Feedback Control ◽  
Piezoelectric Actuator ◽  
Pid Control ◽  
Feedforward Control ◽  
Comparative Investigation ◽  
Preisach Model ◽  
Fuzzy Pid ◽  
Fuzzy Pid Control ◽  
Control Scheme ◽  
Feedforward Controller

Piezoelectric actuator is widely used in the field of micro/nanopositioning. However, piezoelectric hysteresis introduces nonlinearity to the system, which is the major obstacle to achieve a precise positioning. In this paper, the Preisach model is employed to describe the hysteresis characteristic of piezoelectric actuator and an inverse Preisach model is developed to construct a feedforward controller. Considering that the analytical expression of inverse Preisach model is difficult to derive and not suitable for practical application, a digital inverse model is established based on the input and output data of a piezoelectric actuator. Moreover, to mitigate the compensation error of the feedforward control, a feedback control scheme is implemented using different types of control algorithms in terms of PID control, fuzzy control, and fuzzy PID control. Extensive simulation studies are carried out using the three kinds of control systems. Comparative investigation reveals that the fuzzy PID control system with feedforward compensation is capable of providing quicker response and better control accuracy than the other two ones. It provides a promising way of precision control for piezoelectric actuator.

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