Asymmetries in the Disturbance Compensation Methods for the Stable and Unstable First Order Plants

Huba, Mikuláš; Bisták, Pavol; Vrančić, Damir; Žáková, Katarı́na

doi:10.3390/sym12101595

Cited by 9 publications

(24 citation statements)

References 19 publications

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“…Use of output disturbances was typical for the internal model control (IMC). Since it lead to several problems in control of integrative and unstable plants (as unobservable output disturbances of integrative plants, see e.g., [21,41], or unbounded disturbances of unstable ones [42]), it is more appropriate to deal with input disturbances d, as in ADRC. There, all the plant-model discrepancies and external actions are merged into an eqwuivalent input disturbances.…”

Section: Extended State Observermentioning

confidence: 99%

A Set of Active Disturbance Rejection Controllers Based on Integrator Plus Dead-Time Models

et al. 2021

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The paper develops and investigates a novel set of constrained-output robust controllers with selectable response smoothing degree designed for an integrator-plus-dead-time (IPDT) plant model. The input-output response of the IPDT system is internally approximated by several time-delayed, possibly higher-order plant models of increasing complexity. Since they all contain a single integrator, the presented approach can be considered as a generalization of active disturbance rejection control (ADRC). Due to the input/output model used, the controller commissioning can be based on a simplified process modeling, similar to the one proposed by Ziegler and Nichols. This allows it to be compared with several alternative controllers commonly used in practice. Its main advantage is simplicity, since it uses only two identified process parameters, even when dealing with more complex systems with distributed parameters. The proposed set of controllers with increasing complexity includes the stabilizing proportional (P), proportional-derivative (PD), or proportional-derivative-acceleration (PDA) controllers. These controllers can be complemented by extended state observers (ESO) for the reconstruction of all required state variables and non-measurable input disturbances, which also cover imperfections of a simplified plant modeling. A holistic performance evaluation on a laboratory heat transfer plant shows interesting results from the point of view of the optimal least sensitive solution with smooth input and output.

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Section: Extended State Observermentioning

confidence: 99%

A Set of Active Disturbance Rejection Controllers Based on Integrator Plus Dead-Time Models

et al. 2021

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“…In order to generalize and modify SP (and other DTCs) for all types of processes (e.g., integrating and unstable), we first need to interpret it in a more concise way. For several decades now, SP modifications for integrating and unstable systems have not been explained sufficiently consistently (as, e.g., discussed in [18]). This can be one of the sources of distrust of DTCs expressed in [9,11], or in surveys on the importance of control structures for introductory control courses [28].…”

Section: Modelling and Controller Design For The Simplest Time-delayed Processesmentioning

confidence: 99%

“…Moreover, as Ziegler and Nichols [23] pointed out in their pioneering work, which was later followed by numerous other contributions in the area of Active Disturbance Rejection Control (ADRC, [24,25]) or Model Free Control (MFC, [26]), but they have already been noticed by authors from the field of PID control [12,27], the simple integrating models can also be attractive for the design of simplified DTCs on the simplest stable processes [18].…”

Section: Introductionmentioning

confidence: 99%

“…The stabilizing controller designed correctly for an unstable plant can first yield a stable circuit with known dominant dynamics, for which we then propose a disturbance observer in the usual way [17]. Alternatively, we may design the feedforward control and disturbance reconstruction and compensation separately, and use reference models to incorporate a stabilizing controller into the overall structure without nominally affecting the operation of the basic (lower-level) loops [18].…”

Section: Introductionmentioning

confidence: 99%

“…The second aim is to analyse in details all significant features of the discrete-time Smith predictor inspired solutions applied possibly also to unstable and integral plants [14,[16][17][18]21,22]. This, however, requires elimination of the unstable plant mode from the disturbance response and also elimination of the disturbance signal from the controller structure.…”

Section: Introductionmentioning

confidence: 99%

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Dead-Time Compensation for the First-Order Dead-Time Processes: Towards a Broader Overview

et al. 2021

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The article reviews the results of a number of recent papers dealing with the revision of the simplest approaches to the control of first-order time-delayed systems. The concise introductory review is extended by an analysis of two discrete-time approaches to dead-time compensation control of stable, integrating, and unstable first-order dead-time processes including simple diagnostics of the model used and focusing on the possibility of simplified but reliable plant modelling. The first approach, based on the first historically known dead-time compensator (DTC) with possible dead-beat performance, is based on the reconstruction of the actual process variables and the compensation of input disturbances by an extended state observer (ESO). Such solutions play an important role both in a disturbance observer (DOB) based control and in an active disturbance rejection control (ADRC). The second approach considered comes from the Smith predictor with two degrees of freedom, which combines feedforward control with output disturbance reconstruction and compensation by the parallel plant model. It is shown that these two approaches offer advantageous properties in the case of actuator limitations, in contrast to the commonly used PID controllers. However, when applied to integrating and unstable first-order systems, the unconstrained and possibly unobservable output disturbance signal of the second solution must be eliminated from the control loop, due to the hidden structural instability of the Smith predictor-like solutions. The modified solutions, usually referred to as filtered Smith predictor (FSP), then no longer provide a disturbance signal and thus no longer fully fit into the concept of Industry 4.0, which is focused on further optimization, predictive maintenance in dynamic systems, diagnosis, fault detection and fault identification of dynamic processes and forms the basis for the digitalization of smart production. Nevertheless, the detailed analysis of the elimination of the unstable disturbance response mode is also worth mentioning in terms of other possible solutions. The application of both approaches to the control of a thermal process shows almost equivalent quality, but with different dependencies on the tuning parameters used. It is confirmed that a more detailed identification of the controlled process and the resulting higher complexity of the control algorithms does not necessarily lead to an increase in the resulting quality of the transients, which underlines the importance of the simplified plant modelling for practice.

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Design of PI controller parameters of a CSI‐fed SCIM drive ensuring high damping ratio and maximum system stability

Tripathi¹,

Vaish

Pandey

2021

Adv Control Appl

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The control scheme for an electric motor drive is generally implemented by involving proportional‐integral (PI) controllers in current and speed feedback control loops. A good design of PI controller parameters has always been a challenging task for control system design engineers. This paper describes the D‐decomposition method for the design of the parameters of involved DC‐link current and speed PI controllers in closed‐loop scheme of a pulse width‐modulated, current source inverter (CSI)‐fed squirrel‐cage induction motor drive. The PI controllers ensure the stable operation of CSI‐fed induction motor in natural unstable operating region of its torque‐slip characteristic. In order to achieve smoother speed tracking performance with minimum overshoot/undershoot, the damping ratio has been pre‐specified while designing the PI controller parameters using the D‐decomposition method. Simulation results have been presented to confirm the design and have been compared with the results already published.

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Asymmetries in the Disturbance Compensation Methods for the Stable and Unstable First Order Plants

Cited by 9 publications

References 19 publications

A Set of Active Disturbance Rejection Controllers Based on Integrator Plus Dead-Time Models

A Set of Active Disturbance Rejection Controllers Based on Integrator Plus Dead-Time Models

Dead-Time Compensation for the First-Order Dead-Time Processes: Towards a Broader Overview

Design of PI controller parameters of a CSI‐fed SCIM drive ensuring high damping ratio and maximum system stability

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