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The optimal design of a proportional-integral-derivative controller with two cascaded first-order low-pass filters (PID-FF) for non-ideal buck converters faces significant challenges, including effective disturbance rejection, robustness to parameter variations, and the mitigation of high-frequency signal noise, with existing approaches often struggling and leading to suboptimal performance in practical applications. This study addresses these challenges by introducing a constraint on the open-loop crossover frequency to mitigate high-frequency noise and ensuring the controller prioritizes maintaining constant output voltage and robust responsiveness to input voltage and load current variations. This study also introduces an innovative metaheuristic algorithm, the opposition-based snake optimizer with pattern search (OSOPS), designed to address these limitations. OSOPS enhances the Snake Optimizer (SO) by integrating opposition-based learning (OBL) and Pattern Search (PS), thereby improving its exploration and exploitation capabilities. The proposed algorithm design includes a crossover frequency constraint aimed at counteracting high-frequency noise and ensuring robust performance under diverse disturbances. The efficacy of the OSOPS algorithm is demonstrated through rigorous statistical box plot analysis and convergence response comparisons with the original SO algorithm. Additionally, we systematically compare the performance of the OSOPS-based PID-FF-controlled non-ideal buck converter system against systems utilizing the original SO algorithm and the classical pole placement (PP) method. This evaluation encompasses transient and frequency responses, disturbance rejection, and robustness analysis. The results reveal that the OSOPS-based system outperforms the SO- and PP-based systems with 14.21 % and 32.10 % faster rise times, along with 15.38 % and 84.95 % faster settling times, respectively. The OSOPS and SO systems also exhibit higher bandwidths, exceeding the PP-based system by 18.74 % and 17.03 %, respectively. By addressing the key challenges in PID-FF controller design for non-ideal buck converters, this study provides a substantial advancement in control strategy, promising enhanced performance in practical applications.

This paper presents a linear parameter varying (LPV) interpolation modeling method and modal-based pole placement (PP) control strategy for the ball screw drive (BSD) with varying dynamics. The BSD is modeled as a global LPV model with position-load dependence by selecting position and load as scheduling variables. The global LPV model is obtained from local subspace closed-loop identification and LPV interpolation modeling. A modal-based global LPV model is obtained through the similarity transformation. Based on this model, a modal-based LPV PP control strategy is proposed to achieve various modal control. Specifically, a state feedback control structure with an LPV state observer is designed to realize online state estimation and real-time state feedback control of modal state variables which cannot be measured directly. The steady-state error is minimized by introducing an error state space (SS) model with the integral effects. Moreover, the stability of the closed-loop system is analyzed according to the controllable decomposition and principle of separation. It is experimentally demonstrated that the proposed modal-based LPV PP control strategy can effectively achieve precise tracking and outstanding robustness meantime. • A global LPV model of the BSD is built by interpolation modeling. • A modal-based LPV pole placement control is proposed to achieve modal control. • The proposed modeling and control achieve precise tracking and excellent robustness. [ABSTRACT FROM AUTHOR]

This paper presents the design of an H∞-based Restricted Static Output Feedback (RSOF) controller with regional pole placement in Linear Matrix Inequality (LMI) framework for Load Frequency Control (LFC) of a 2-area Interconnected Power System (IPS). The motivation behind the RSOF controller is to develop a controller with a predefined structure for implementing centralized and decentralized control strategy as per need. In this work a new stabilization criterion is developed by choosing circle and strip LMI regions for pole-placement along with the use of Particle Swarm Optimization (PSO) technique to tune the scalar parameters for the feasibility of the developed LMI criterion. The designed controller (both centralized and decentralized structure) with the above modifications improves the transient response of the frequency output. The designed controller is tested on a 2-area LFC model incorporating both conventional and renewable energy sources. Simulation results validate the effectiveness of the designed controller in attenuating disturbance and also enhancing the transient response. Also, simulation studies are carried out to test the robustness against time delays and cyberattacks. A comparative analysis is presented for various controllers, highlighting their performance differences. [ABSTRACT FROM AUTHOR]

In this study, the semi-discretization technique is employed to establish a discrete representation of a modified Leslie-Gower prey-predator system that includes a Holling II type functional response. The dynamics of this model are then analyzed through the application of center manifold theory and bifurcation theory. We present comprehensive results for the local stability of the fixed points across the entire parameter space. Additionally, we provide sufficient conditions for the occurrence of flip bifurcation and Neimark-Sacker bifurcation. Besides, the system has experienced a flip bifurcation to chaos controlled using the method of chaos control, viz., state feedback method, pole placement technique, and hybrid control strategy. Furthermore, we provide specific conditions to ensure that bifurcation and chaos can be stabilized. Finally, numerical simulations are conducted to validate theoretical analysis and illustrate several new complex dynamical behaviors between two species. [ABSTRACT FROM AUTHOR]

This article presents a novel control approach using a two‐degree‐of‐freedom (2‐DOF) Smith predictor structure for double integrating plus time delay plants. The PD and PID controllers, integral components of the Smith predictor scheme, serve distinct roles in the control process. The PD controller is responsible for set‐point tracking, while both PD and PID controllers contribute to the rejection of load disturbances. Each controller is designed using the pole placement technique, with an appropriate tuning parameter established to balance performance and robustness effectively. A low‐pass filter is incorporated to improve the response of the set‐point signal by attenuating high‐frequency noise. The proposed method's effectiveness is compared with Skogestad internal model control, a well‐known PID tuning method, to benchmark performance improvements and demonstrate the advantages of the 2‐DOF Smith predictor approach. Simulation and comparison analysis demonstrates that the proposed controller setting is suitable for industrial applications due to its quick set‐point tracking, effective load disturbance rejection, and smooth control signal. The study highlights the practical benefits of the 2‐DOF Smith predictor in enhancing industrial control system performance and suggests directions for future research, including experimental validation and robustness analysis under varying system parameters. [ABSTRACT FROM AUTHOR]

This paper presents a novel approach to model reference adaptive control inspired by the adaptive pole‐placement controller (APPC) of Elliot and based on retrospective cost optimization. Retrospective cost model reference adaptive control (RC‐MRAC) is applicable to nonminimum‐phase (NMP) systems assuming that the NMP zeros are known. Under this assumption, the advantage of RC‐MRAC is a reduced need for persistency. The present paper compares APPC and RC‐MRAC under various levels of persistency in the command for minimum‐phase and NMP systems. It is shown numerically that the model‐following performance of RC‐MRAC is less sensitive to the persistency of the command compared to APPC at the cost of knowledge of the NMP zeros. RC‐MRAC is also shown to be applicable for disturbance rejection under unknown harmonic disturbances. [ABSTRACT FROM AUTHOR]

Functional electrical stimulation (FES) has shown potential in rehabilitative exercises for patients recovering from spinal cord injuries. In recent developments, conventional open-loop FES control techniques have evolved into closed-loop systems that employ feedback controllers for automation. However, closed-loop FES systems often face challenges due to muscle nonlinear effects, such as fatigue, time delays, stiffness, and spasticity. Therefore, an accurate non-linear knee model is required during the design stage, and precise tuning of the feedback controller parameters is vital. A proportional– integral–derivative (PID) controller is commonly used as a feedback controller due to its simplicity and ease of implementation. However, most PID tuning methods are complex and time consuming. This paper investigates the viability of employing the pole placement technique for tuning a PID controller that regulates the non-linear knee extension model. The pole placement method aims to improve the control and adaptability of the PID controller in closed-loop FES systems, specifically by facilitating knee extension exercises. MATLAB Simulink was used to assess the effectiveness of this tuning approach. Results showed that the PID controller performed satisfactorily without non-linearities, but performance varied with the inclusion of specific non-linearities. The pole placement tuning method facilitated preliminary assessments of PID controller performance, preceding highly advanced optimization. [ABSTRACT FROM AUTHOR]

This research paper addresses the issue of frequency deviation in MG, which has emerged as a significant challenge in the context of power supply to loads, particularly in the context of unpredictable and random climate shifts. The system was evaluated under two distinct scenarios: one lacking any control methodologies, relying on conventional techniques to guarantee uninterrupted power supply to the load, and the other utilizing a PID controller calibrated through the Pole Placement method. The uncontrolled system exhibited considerable frequency fluctuations, exceeding ±1.5 Hz, which undermined its stability and rendered it unsuitable for supplying power to loads that require precise frequency levels. Conversely, the introduction of the controller resulted in substantial enhancements, reducing frequency distortion and facilitating more rapid stabilization, with the frequency remaining within ±0.5 Hz shortly after system startup. These outcomes underscore the viability of this approach in ensuring stable frequency regulation in MG environments.

The problem of finding the arrangement of closed-loop control system poles that minimizes an objective function is considered. The system optimality criterion is the value of the H∞ norm of the frequency transfer function relative to the disturbance with constraints imposed on the system pole placement and the values of the H∞ norm of the sensitivity function and the transfer function from measurement noise to control. An optimization problem is formulated as follows: the vector of variables consists of the characteristic polynomial roots of the closed loop system with the admissible values restricted to a given pole placement region; in addition to the optimality criterion, the objective function includes penalty elements for other constraints. It is proposed to use a logarithmic scale for the moduli of the characteristic polynomial roots as elements of the vector of variables. The multi-extremality problem of the objective function is solved using the multiple start procedure. A coordinate descent modification with a pair of coordinates varied simultaneously is used for search. [ABSTRACT FROM AUTHOR]

In industrial processes, achieving an efficient flow is paramount as various loops are controlled through flow control. To optimize this flow, it is essential to monitor various influential components such as control valves, flow sensors, as well as input and output parameters to the valve. To maintain the desired flow rate at the outlet of the control valve, it's imperative that the valve's inflow remains higher than the desired output flow rate. In most applications, fluctuations in the inflow rate are typically not considered as a significant factor affecting changes in the output flow which is a key driving component leading to our research objective. This research paper's contribution is estimation of control valve's inlet flow rate without the need for physical sensors and validation of estimated flow rate. This estimator relies on an outflow measurement from an orifice flow meter and employs a first order process with dead time model to deduce the inflow to the control valve. The process model is formulated through data driven system identification, employing the input-output characteristics of the system. Furthermore, a pole-placementbased estimator is developed utilizing real-world data. The novelty of the approach is estimation of the flow rate at valve input which is overlooked by many researchers. To validate the performance of this estimator, it is deployed to compute the inflow in a real-life practical system. The results reveal a root mean square error of 0.029, signifying the accuracy and reliability of the designed estimator. The estimator performed better in terms of reduced root mean square error when compared to other methods. [ABSTRACT FROM AUTHOR]

Abstract This article presents a novel control approach using a two‐degree‐of‐freedom (2‐DOF) Smith predictor structure for double integrating plus time delay plants. The PD and PID controllers, integral components of the Smith predictor scheme, serve distinct roles in the control process. The PD controller is responsible for set‐point tracking, while both PD and PID controllers contribute to the rejection of load disturbances. Each controller is designed using the pole placement technique, with an appropriate tuning parameter established to balance performance and robustness effectively. A low‐pass filter is incorporated to improve the response of the set‐point signal by attenuating high‐frequency noise. The proposed method's effectiveness is compared with Skogestad internal model control, a well‐known PID tuning method, to benchmark performance improvements and demonstrate the advantages of the 2‐DOF Smith predictor approach. Simulation and comparison analysis demonstrates that the proposed controller setting is suitable for industrial applications due to its quick set‐point tracking, effective load disturbance rejection, and smooth control signal. The study highlights the practical benefits of the 2‐DOF Smith predictor in enhancing industrial control system performance and suggests directions for future research, including experimental validation and robustness analysis under varying system parameters.

The optimal design of a proportional-integral-derivative controller with two cascaded first-order low-pass filters (PID-FF) for non-ideal buck converters faces significant challenges, including effective disturbance rejection, robustness to parameter variations, and the mitigation of high-frequency signal noise, with existing approaches often struggling and leading to suboptimal performance in practical applications. This study addresses these challenges by introducing a constraint on the open-loop crossover frequency to mitigate high-frequency noise and ensuring the controller prioritizes maintaining constant output voltage and robust responsiveness to input voltage and load current variations. This study also introduces an innovative metaheuristic algorithm, the opposition-based snake optimizer with pattern search (OSOPS), designed to address these limitations. OSOPS enhances the Snake Optimizer (SO) by integrating opposition-based learning (OBL) and Pattern Search (PS), thereby improving its exploration and exploitation capabilities. The proposed algorithm design includes a crossover frequency constraint aimed at counteracting high-frequency noise and ensuring robust performance under diverse disturbances. The efficacy of the OSOPS algorithm is demonstrated through rigorous statistical box plot analysis and convergence response comparisons with the original SO algorithm. Additionally, we systematically compare the performance of the OSOPS-based PID–FF–controlled non-ideal buck converter system against systems utilizing the original SO algorithm and the classical pole placement (PP) method. This evaluation encompasses transient and frequency responses, disturbance rejection, and robustness analysis. The results reveal that the OSOPS-based system outperforms the SO- and PP-based systems with 14.21 % and 32.10 % faster rise times, along with 15.38 % and 84.95 % faster settling times, respectively. The OSOPS and SO systems also exhibit higher bandwidths, exceeding the PP-based system by 18.74 % and 17.03 %, respectively. By addressing the key challenges in PID-FF controller design for non-ideal buck converters, this study provides a substantial advancement in control strategy, promising enhanced performance in practical applications.

In this paper, a novel approach for finite-time average consensus within a prescribed time is introduced and explored for a multi-agent system running ordinary nearest-neighbor protocols. Differently from the available approaches of finite-time consensus, it exploits the special motion of one agent properly tuned, through an appropriate algorithm based on past values of its own local data. The leader’s motion influence input is built upon a set of internal variables, and it is designed to achieve a finite-time transient behavior while keeping the initial consensus value unchanged. A preliminary procedure is set to retrieve the algorithm’s parameters from data collected in an initial experimental stage, so that the overall algorithm can be run in a fully data-driven fashion. Simulation results put in evidence the effectiveness of the approach, together with some features and drawbacks of the proposed algorithm, so they draw some important insights regarding its use and future research lines.

To enhance the stability of power system, a power system stabilizer (PSS) is one of the control mechanisms installed in the power plants. A suitable PSS parameters set can help in reducing the power swing. In general, the design of PSS parameters is performed based on a nominal operating condition of the power system. In this paper, a multi‐objective optimization algorithm based on pole placement technique is proposed to find a robust PSS parameters set. The proposed strategy searches for the optimal PSS parameters under multiple operating conditions of the generator. Preliminary simulation results on a single machine infinite bus (SMIB) model show that the proposed PSS parameters design method can further improve the robustness of the overall power systems performance under different types of disturbance. © 2023 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC. [ABSTRACT FROM AUTHOR]

This paper presents analytical and numerical studies on the active assignment of poles to a planetary gear system for vibration control in order to avoid resonance. This involves feeding back the displacement and velocity to add active stiffness and damping, respectively. A rotating frame of reference has been adopted in order to describe the dynamics over a broad range of rotational speed. As an illustration, the closed loop poles were assigned to the translational directions of the sun gear first and thereafter the carrier. This can be achieved by placing the actuators on the outer race of their bearings mounted onto their shafts. The controller was designed such that the closed loop poles can be assigned considering the rotational speed. In this way, it is possible to apply a robust pole-placement that is insensitive to the rotational speed. Numerical examples, where sensors and actuators were collocated, are presented to demonstrate the feasibility of the method when applied to a physical system. The results shows that the active control force and power required for the system, when rotating, can be determined using a rotating frame of reference and transformed for practical implementation. In addition, the same conjugate poles were assigned to the carrier and sun gear and the optimal place to apply control forces was discovered. This depends upon the control power required to shift the poles from one location to another. The results show that more control power will be required to shift the poles of the system when poles were assigned to the sun gear, where higher active bearing stiffness was required. Therefore, the optimal place to assign poles in this case is the carrier due to lower control power required to shift the system poles. [ABSTRACT FROM AUTHOR]

Switched mode DC-DC converters play an important role in today's renewable energy systems, electric Vehicles, consumer electrical appliances, and many more. While many researchers have designed controllers for DC-DC converters, achieving low implementation cost remains a significant hurdle. This paper proposes a cost-effective observer-based pole placement controller for a PWM voltage-controlled Buck converter with clear step by step design approach. The state space averaged model of the DC-DC power converter is used to design pole placement with integrator compensator and full state observer. Pole placement is employed to improve the transient and steady state behavior of Voltage reference tracking response and full state observer is applied to extract the inductor current with the aim of removing the actual current sensor. Design specifications are set to a settling time of less than 5 msec and an overshoot of less than 5 %. While designing Observer-Controller combination, the separation principle, designing the controller and observer independently, is utilized by placing the observer poles far to the left of the controller poles for the Observer to converge faster. The designed controller and observer is verified with simulation in MATLAB/SIMULINK software and design of developed controller and observer are realized using low-cost analog electronics circuit components The results shows that the proposed system's strength in tracking the reference output voltage even in the presence of input voltage disturbance and the mean value of inductor current is well extracted having only the output voltage and MOSFET gate signal.

In this paper, linear quadratic regulator (LQR) control is applied to a Cuk converter, and mathematical modeling of the converter is done using state space averaging (SSA) in continuous conduction mode (CCM). The primary focus is to design a controller for the converter and maintain output voltage within 1% of the prescribed value when there is a unit step disturbance in the input. The design done by using MATLAB improved control of the converter from that with a conventional controller when tested with disturbances. The controller did not influence the system's stability, when assessed from the Bode plot. Despite the existence of disturbances, the findings prove the efficacy of the suggested approach, and the proposed controller can track the desired output voltage in less than 14 ms. The LQR control was developed for various applications of the Cuk converter, such as in a photovoltaic system and a wind system.

The pole assignment method is commonly used in the design of three-loop autopilot, and the constraints for the key parameter that the open-loop crossover frequency was blurred. By concluding the analytical relationship between control gains, the close-loop poles and the open-loop crossover frequency, the control system design problem is transformed into a judicious choice of the open-loop crossover frequency. Combined with engineering experience of the Canard layout missile, the constraint criteria and modified methods for the selection of the open-loop crossover frequency of the rudder bandwidth, the fin rate, the close-loop zeros and the gain polarity are discussed. The applicability of the criteria is verified in typical conditions.

Summary In this contribution, we propose a detailed study of interpolation‐based data‐driven methods that are of relevance in the model reduction and also in the systems and control communities. The data are given by samples of the transfer function of the underlying (unknown) model, that is, we analyze frequency‐response data. We also propose novel approaches that combine some of the main attributes of the established methods, for addressing particular issues. This includes placing poles and hence, enforcing stability of reduced‐order models, robustness to noisy or perturbed data, and switching from different rational function representations. We mention here the classical state‐space format and also various barycentric representations of the fitted rational interpolants. We show that the newly‐developed approaches yield, in some cases, superior numerical results, when comparing to the established methods. The numerical results include a thorough analysis of various aspects related to approximation errors, choice of interpolation points, or placing dominant poles, which are tested on some benchmark models and data‐sets. [ABSTRACT FROM AUTHOR]

In this paper, a novel active damping technique is proposed that can be applied in AC power converters with LCL filters. Active damping is performed in the discrete domain based on a single measurement of the output LCL filter current. The parameter tuning procedure, which is based on pole-placement, is applied in a new active damping structure. This simplifies the design of the cascaded control loop, which is superimposed onto the inner loop with the active damping, which results in improved controller dynamics and robustness. The proposed active damping method is applied with the cascaded-output current controller main loop of an AC power converter with a resonant LCL filter. The dynamic performance and robustness of the novel active damping method are analyzed through a series of simulation and experimental tests. Simulation and experimental results show that proposed active damping technique enables successful and effective decoupling of the local active damping and the main control loop design. [ABSTRACT FROM AUTHOR]

In this paper, linear quadratic regulator (LQR) control is applied to a Cuk converter, and mathematical modeling of the converter is done using state space averaging (SSA) in continuous conduction mode (CCM). The primary focus is to design a controller for the converter and maintain output voltage within 1% of the prescribed value when there is a unit step disturbance in the input. The design done by using MATLAB improved control of the converter from that with a conventional controller when tested with disturbances. The controller did not influence the system's stability, when assessed from the Bode plot. Despite the existence of disturbances, the findings prove the efficacy of the suggested approach, and the proposed controller can track the desired output voltage in less than 14 ms. The LQR control was developed for various applications of the Cuk converter, such as in a photovoltaic system and a wind system. [ABSTRACT FROM AUTHOR]

Tuning of PID/PIDD2 controllers are proposed in the paper for integrating processes with time delay via the state space pole placement method. The tuning formulas give the controller parameters in terms of a given maximum sensitivity. An observer-based PID structure is proposed to implement the ideal PID or PIDD2 controllers. The structure utilizes a model-independent observer to estimate the various order of the derivatives of the plant output, thus the sensitivity of the derivatives on the measurement noise can be reduced. Simulation results show that the tuning formulas can achieve good compromise among robustness, disturbance rejection, and noise attenuation for the integrating processes. • Tuning of PID/PIDD2 controller is proposed for integrating plants (IPTD, DIPTD, and IFOPTD) using based on state-space pole placement. • Tuning formulas ensure desired robustness by incorporating maximum sensitivity (M s) and plants parameters. • Ideal PID/PIDD2 controller is implemented with observer-based PID structure to reduce effect of measurement noise. [ABSTRACT FROM AUTHOR]

This work presents the comparative study among pole-placement (PP), optimal-control using output-feedback (OCOF), linear-quadratic regulator (LQR), and PID controllers for the twin rotor multi-input multi-output system (TRMS). The pitch and yaw are key attributes for stabilizing the TRMS MIMO system and control of flight. The main objective of this study is to use these classical controller techniques to monitor the pitch and yaw angles of TRMS and show the result of these techniques. Simulation results depicts the actual performance and reveals how PP outperforms the other techniques. [ABSTRACT FROM AUTHOR]

There exists a critical transition before dramatic deterioration of a complex dynamical system. Recently, a method to predict such shifts based on High‐Dimension Low‐Sample‐Size (HDLSS) data has been developed. Thus based on the prediction, it is important to make the system more stable by feedback control just before such critical transitions, which we call re‐stabilization. However, the re‐stabilization cannot be achieved by traditional stabilization methods such as pole placement method because the available HDLSS data is not enough to get a mathematical system model by system identification. In this article, a model‐free pole placement method for re‐stabilization is proposed to design the optimal input assignment and feedback gain for undirected network systems only with HDLSS data. The proposed method is validated by numerical simulations. [ABSTRACT FROM AUTHOR]

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The pole assignment method is commonly used in the design of three-loop autopilot, and the constraints for the key parameter that the open-loop crossover frequency was blurred. By concluding the analytical relationship between control gains, the close-loop poles and the open-loop crossover frequency, the control system design problem is transformed into a judicious choice of the open-loop crossover frequency. Combined with engineering experience of the Canard layout missile, the constraint criteria and modified methods for the selection of the open-loop crossover frequency of the rudder bandwidth, the fin rate, the close-loop zeros and the gain polarity are discussed. The applicability of the criteria is verified in typical conditions. [ABSTRACT FROM AUTHOR]

An improved technique for the design of decentralized dynamic decoupled proportional-integral (PI) controllers to control many variables of column flotation was developed and implemented in this paper. This work was motivated by challenges when working with multiple inputs and multiple outputs (MIMO) systems that are not controllable by conventional linear feedback controllers. Conventional feedback control design consists of various drawbacks when it comes to complex industrial processes. The introduction of decentralization, decoupling, and many advanced controls design methods overcomes these drawbacks. Hence, the design and implementation of control systems that mitigate stability for MIMO systems are important. The developed closed-loop model of the flotation process is implemented in a real-time platform using TwinCAT 3.1 automation software and CX5020 Beckhoff programmable logic controllers (PLC) through the model transformation technique. The reasons for using the CX5020 as an implementation environment were motivated by the reliability, and is built according to new industry standards, allowing transformation, which makes it more advantageous to be used more than any other PLCs. This is done to validate the effectiveness of the recommended technique and prove its usability for any multivariable system. Comparable numerical results are presented, and they imply that industrial usage of this method is highly recommended. [ABSTRACT FROM AUTHOR]

There is a critical transition before a high-dimensional network system completely deteriorates. The Dynamical Network Marker (DNM) theory has been developed for the early prediction of such critical transitions by only using High-Dimension Small-Sample-Size (HDSSS) data. This article presents a model-free dominant pole placement approach for restabilizing the high-dimensional network systems towards avoidance of critical transitions by early treatment. Instead of traditional model-based pole placement, we present a model-free exact dominant pole placement method with dominant eigenvectors of the system matrix, which can be estimated from HDSSS data of system states. We further introduce two approximations of exact dominant pole placement to reduce the complexity of implementing restabilization. The first one is to approximate the right dominant eigenvector-based pole placement by reducing the number of intervened nodes. The second one is to intervene only in the diagonal part of the system matrix. We conduct theoretical analysis and numerical simulations to investigate the performance of the proposed dominant pole placement method.

Active Disturbance Rejection Control (ADRC) is a very promising recent concept for the design of controllers to control systems with uncertainties. Based on an extended state observer, this control structure allows both external disturbances and modeling uncertainties to be actively rejected. The use of the active rejection control of disturbances is gaining more and more interest among the system control community. This is mainly due to its easy design, undemanding implementation and robustness. In this paper, three solutions using the ARDC structure to control fractional-order system are discussed. Two methods taken from the literature are briefly introduced, namely, the fractional-order dynamics rejection scheme (FODRS) and the fractional linear active disturbance rejection control (FLADRC). The basic ideas and technical formulations of these two are presented. A third method, based on the robustness performance introduced by fractional-order controllers, is also proposed in this paper. The proposed design method of the set-point tracking controller is based on the Bode’s ideal transfer function (Bode’s ITF). This will improve the robustness of the control scheme.

The pulse-with modulated (PWM) dc-dc buck-boost converter is a non-minimum phase system, which requires a proper control scheme to improve the transient response and provide constant output voltage during line and load variations. The pole placement technique has been proposed in the literature to control this type of power converter and achieve the desired response. However, the systematic design procedure of such control law using a low-cost electronic circuit has not been discussed. In this paper, the pole placement via state-feedback with an integral control scheme of inverting the PWM dc-dc buck-boost converter is introduced. The control law is developed based on the linearized power converter model in continuous conduction mode. A detailed design procedure is given to represent the control equation using a simple electronic circuit that is suitable for low-cost commercial applications. The mathematical model of the closed-loop power converter circuit is built and simulated using SIMULINK and Simscape Electrical in MATLAB. The closed-loop dc-dc buck-boost converter is tested under various operating conditions. It is confirmed that the proposed control scheme improves the power converter dynamics, tracks the reference signal, and maintains regulated output voltage during abrupt changes in input voltage and load current. The simulation results show that the line variation of 5 V and load variation of 2 A around the nominal operating point are rejected with a maximum percentage overshoot of 3.5% and a settling time of 5.5 ms. [ABSTRACT FROM AUTHOR]

Since the Cuk converter is a non-minimum phase system with an unstable internal dynamic, it is challenging to employ control methods such as input–output linearization to ensure the closed-loop system stability. This paper proposes an objective holographic feedback nonlinear control (OHFNC) method without static deviation to regulate fourth-order Cuk converters. A Cuk converter operating in the continuous conduction mode is adopted, and the input inductor current and output capacitor voltage of the system are selected as control target quantities. The OHFNC method aims to configure a nonlinear system with poles near the equilibrium point, and place them in desired positions. The target quantities are separately constrained by feedback coefficients, which forces them to converge to their corresponding reference trajectories. Accordingly, an integration link is introduced to compensate for the reference current error when the system is heavily loaded. Finally, simulation and experimental results show that the OHFNC method has a stronger robustness and a faster transient response than fractional-order PIλ dual-loop control. [ABSTRACT FROM AUTHOR]

Accurate modeling and efficient control of inverted pendulums have always been a challenge for researchers. So, the current research aims to achieve the following objectives: (I) proposing a comprehensive dynamic model for the inverted pendulums which accounts for the flexibility of the pendulum bar and (II) suggesting an appropriate supervisory fuzzy-pole placement control strategy for stabilizing the pendulum system. Using a Lagrangian formulation, the equations of motion are derived and linearized. Then, a state feedback controller with a reduced-order observer is designed to stabilize the system. Closed-loop simulations reveal that at least six modes shall be considered in the dynamic equations. To improve the quality of the transient response, a novel fuzzy system is developed for real-time assignment of the controller poles. Simulation results demonstrate that the control quality is significantly improved by adding a supervisory fuzzy system to the control loop. The developed approach for dynamic modeling of the system, and the idea of multi-level fuzzy-pole placement control architecture developed in this paper, may be successfully applied to improve the response specifications in other dynamic systems. [ABSTRACT FROM AUTHOR]

Active Disturbance Rejection Control (ADRC) is a very promising recent concept for the design of controllers to control systems with uncertainties. Based on an extended state observer, this control structure allows both external disturbances and modeling uncertainties to be actively rejected. The use of the active rejection control of disturbances is gaining more and more interest among the system control community. This is mainly due to its easy design, undemanding implementation and robustness. In this paper, three solutions using the ARDC structure to control fractional-order system are discussed. Two methods taken from the literature are briefly introduced, namely, the fractional-order dynamics rejection scheme (FODRS) and the fractional linear active disturbance rejection control (FLADRC). The basic ideas and technical formulations of these two are presented. A third method, based on the robustness performance introduced by fractional-order controllers, is also proposed in this paper. The proposed design method of the set-point tracking controller is based on the Bode's ideal transfer function (Bode's ITF). This will improve the robustness of the control scheme. [ABSTRACT FROM AUTHOR]

In the current age of globalization, the development of autopilots is superficial as the standard of living is improved through aerial surveillance, defense applications, and door- to-door transportation. To design the PID controller, a mathematical model is created to address the system identification for estimating longitudinal derivatives and to study the handling qualities of aircraft in order to improve piloting performance. This paper exhibits a comparative assessment between the classical closed-loop PID tuning methods like ZN, Modified ZN, Tyreus-luyben, Astrom- Hagglund and the modern control techniques like pole placement, LQR for the pitch controller design. The simulation results are displayed in the time-domain, which demonstrates the effectiveness of the approach used to design a robust controller.

Left ventricular assist devices (LVADs) technology requires developing and implementing intelligent control systems to optimize pump speed to achieve physiological metabolic demands for heart failure (HF) patients. This work aimed to design an advanced tracking control algorithm to drive an LVAD under different physiological conditions. The pole placement method, in conjunction with the sliding mode control approach (PP-SMC), was utilized to construct the proposed control method. In this design, the method was adopted to use neural networks to eliminate system uncertainties of disturbances. An elastance function was also developed and used as an input signal to mimic the physiological perfusion of HF patients. Two scenarios, ranging from rest to exercise, were introduced to evaluate the proposed technique. This technique used a lumped parameter model of the cardiovascular system (CVS) for this evaluation. The results demonstrated that the designed controller was robustly tracking the input signal in the presence of the system parameter variations of CVS. In both scenarios, the proposed method shows that the controller automatically drives the LVAD with a minimum flow of 1.7 L/min to prevent suction and 5.7 L/min to prevent over-perfusion.

PID control is widely applied in industry. However, it is classified as a classical control technique, in that transfer function method is used to represent the ideal and/or practical PID controller. Modern control concepts, such as state feedback, observer, are seldom found in PID research. This paper proposes a state-space PID structure to fill the gap. The classical ideal PID is first shown to be a state-feedback control structure with the plant output and its derivative and integral as the states, and then a model-independent observer is proposed to estimate the states, thus approximate the ideal PID as an observer-based state feedback control structure (state-space PID). Then it is shown that the proposed state-space PID structure is the dual of the linear active disturbance rejection control structure, and it is a general-purposed control structure in that any strictly-proper linear controller with integration can be implemented via the proposed structure. The design of the state-space PID can be done via the well-known pole placement algorithm in modern control. Simulation and experiment results show that state-space PID structure is a practical implementation of ideal PID, which naturally integrates the noise reduction that is separated from PID tuning, and it is a natural generalization of the classical PID to high-order cases.

Linear active disturbance rejection control (LADRC) is a powerful control structure thanks to its performance in uncertainties, internal and external disturbances estimation and cancelation. An extended state observer (ESO) based controller is the key to the LADRC method. In this article, the LADRC scheme combined with a fractional-order integral action (FOILADRC) is proposed to improve the robustness of the standard LADRC. Using the robust closed-loop Bode's ideal transfer function (BITF), an appropriate pole placement method is proposed to design the set-point tracking controller of the FOI-LADRC scheme. Numerical simulations and experimental results on a cart-pendulum system will illustrate the effectiveness of the proposed FOI-LADRC scheme for the disturbance rejection, the set-point tracking and the improved robustness. To illustrate the LADRC control schemes and to verify the performance of the proposed FOI-LADRC, compared to the standard LADRC and IOI-LADRC structures, two tests will be carried out. First, simulation tests on an academic example will be presented to show the effect of the different parameters of the control law on the performance of the closed-loop system. Then, these three control structures are implemented on an experimental test bench, the cart-pendulum system, to show their efficiency and to show the superiority of the proposed method compared to the two other structures. [ABSTRACT FROM AUTHOR]

In this paper, a new method of soft variable structure control for Fractional-Order System (FOS) is proposed to achieve faster response while the control signal is continuous and satisfies actuators' constraints. Our proposed method, by describing a desired commensurate FOS, with the help of a pole placement algorithm and applying an optimization routine, in the form of a procedure, leads the system to the desired character. The routine is done by solving an optimization problem subject to a control signal constraint qua we obtain the fastest response possible in the sense of stability region. The sufficient condition of stability of the control system is developed based on the stability theory of Fractional Order (FO) linear differential equations, and attributes of the Mittag-Leffler function. Finally, an example and corresponding numerical simulations are presented to show the efficiency of the proposed method. In the proposed method, a new control strategy for the FOS is presented, a complex problem is solved in a simple way, and it can exploit the benefits of using FOS in the modeling and control of complex physical phenomena. • A new soft variable structure control for fractional-order systems is generalized called FFFPP. • By a generalized pole placement and an optimization routine, the FFFPP vary controllers' parameters to a faster response. • It achieves a faster response while the control signal is soft, continuous, and satisfying actuators constraints. • The stable controller parameters change during the regulation period; we can use most capabilities of the control system. • A complex problem is solved in a simple way, and it can exploit the benefits of using fractional-order physical systems. [ABSTRACT FROM AUTHOR]

In this paper, we present a new digital resonant current controller that can be applied in single-phase and three-phase alternating current (AC) power converters, based on voltage source inverters (VSI) with pulse width modulation (PWM). Since power converters based on PWM introduce fractional time delays regarding the sampling period (T s), because of the current sampling and PWM command updating techniques that are employed, there is a need to develop analytical tools for precise modelling of these types of delays. To achieve this, the advanced Z-transform is applied in order to model the AC controllers in VSIs with PWM for the general case of a fractional time delay, including power converters with current sampling within a PWM period at any chosen time instance. This new approach to power converter modelling and current sampling allowed us to develop a modified resonant AC current controller for a VSI with RL load, based on the pole-placement parameter tuning method. It includes fractional time delays, which are conventionally employed in the power converter design, in the controller parameter derivations, and introduces the minimal order resonant controller that enables strict placement of all closed-loop control system poles. Simulations and experimental tests are carried out to show the improvements introduced by novel solution in this paper compared with conventional resonant current controllers. In the analysis of dynamic performance and robustness, in this paper conventional indices are applied to compare the proposed controller with a conventional design. • The introduction of the Advanced Z-Transform enables analytical modelling of the plant that includes a fractional time delay. • Novel pole-placement based parameter tuning procedure is presented, which places all closed-loop system poles at required positions. • New controller is compared with existing solution by test runs and conventional dynamic performance and robustness indices. [ABSTRACT FROM AUTHOR]