Compensator Design Research Articles

An Anti‐Attack Neural Sliding Mode Framework Based on a Novel Non‐Fragile Observer

ABSTRACTThis article investigates anti‐attack stabilization with passivity problem of uncertain singular semi‐Markov jump systems (singular S‐MJSs) with exogenous disturbance and delay. An ingenious non‐fragile observer‐based neural sliding mode control (SMC) scheme is put forward to solve the problem. First, considering unmeasured states, a distinctive non‐fragile and decoupled observer, which does not contain the control input or any auxiliary sliding mode compensator design as in existing observer‐based SMC approaches, is established such that the disadvantages of sliding mode switching in observers in existing literature can be avoided. Then, “only one sliding surface” design and a new system analysis route are presented, and the derived sliding surface is accessibly designed. Next, a new version of stochastic admissibility and passivity sufficient condition is given, and a related algorithm via an optimization problem is proposed to determine the controller gain and the observer gain by linear matrix inequalities (LMIs). Further, a novel observer‐based anti‐attack neural SMC law, which utilizes a neural network‐based approach to approximate actuator attack, is proposed to stabilize the singular S‐MJSs against actuator attack. Finally, simulation and comparison results are presented, which demonstrate the effectiveness and superiority of our method.

Reconfiguration and compensation design method for single-DoF closed-chain leg mechanism

Compared with a wheeled robot propelled by a rotary drive, a legged robot equipped with multiple motors on a single leg possesses superior adaptability, while at the cost of high energy consumption and less velocity. Inspired by the California mite, the design method of reconfigurable closed-chain leg mechanism with single degree of freedom (DoF) is proposed for effective striding and smooth propelling. Furthermore, the lower-mobility closed-chain leg mechanism is more appropriate for obtaining high frequency and fast movement with the merits of simple control system and rotary drive. Firstly, a reconfigurable design is performed in the swing phase for a high-knee motion intermittently driven by a walking motor through dynamic coupling. Secondly, its fluctuations in vertical displacement and horizontal speed are compensated through the contact outline curve and variable speed input in the supporting phase. Finally, the simulated performance is analyzed and compared, and a prototype is fabricated for fluctuating and obstacle-crossing experiments.

Modeling and Simulation of Wide-Frequency Characteristics of Electromagnetic Standard Voltage Transformer

To achieve the broadband applicability of standard voltage transformers in “dual high” power systems, an equivalent circuit model of the standard voltage transformer is first established. Using the complex magnetic permeability method and utilizing existing core parameters, the excitation impedance values are obtained. Next, based on the equivalent circuit model, the no-load error function of the standard voltage transformer is analyzed, and through simulation, the no-load error response curve of the standard voltage transformer in the frequency range of 20 Hz to 3000 Hz is derived. The simulation results indicate that within the 20 Hz to 700 Hz range, both the no-load ratio error and the no-load angular error meet the accuracy requirements, with the ratio error within ±0.05% and the angular error within 2′. Additionally, the derivation of the error transfer function demonstrates the correlation between the no-load error values and the number of turns and cross-sectional area of the standard voltage transformer. Simulation results, obtained by increasing and decreasing the number of turns and cross-sectional area by 10%, provide valuable insights for the error compensation and structural design of standard voltage transformers.

New delay‐dependent finite‐time stabilization of Takagi–Sugeno fuzzy approaches for delayed nonlinear systems

AbstractIn this paper, the finite‐time stability and stabilization of nonlinear systems with delays is studied, via a Takagi–Sugeno approach. By using a novel Lyapunov–Krasovskii functional and introducing some fuzzy free‐weighting matrices, sufficient conditions are derived, for bounded and differentiable time‐varying delays in terms of an upper bound of the delay derivatives. Then, we achieve closed‐loop stabilization in finite time through an efficient parallel distributed compensation design. The sufficient conditions are formulated as linear matrix inequalities to achieve the desired performance. Finally, the proposed methodology is applied to various case studies, highlighting its significance.

Dispersion compensation design of high-density stacking RFSS absorbers for wideband applications

Abstract A dispersion compensation design absorber realized by high-density stacking resistive frequency selective surface (RFSS) is proposed for wideband applications. Firstly, the quantitative relationship between the equivalent impedance of RFSS and the permittivity of the effective media is constructed with the help of the transmission matrix method. The dispersion regulation of permittivity is achieved by changing the pattern and the square resistance of RFSS. In terms of absorber design, a uniform absorber with dispersion manipulation is developed as a precursor absorber. The uniform absorber has an absorption performance better than −8.5 dB above 2 GHz at normal incidence. The loss mechanism is analyzed in detail by electric field distribution and surface power loss density distribution, indicating that the uniform design cannot achieve thickness saving when extending to low frequency. Therefore, a dispersion compensation design absorber is proposed to extend −10 dB bandwidth to 1.64–28.8 GHz. Experiment results agree well with the simulation results, validating the analytic methods and design principles.

Disturbance Compensator Design Based on Dilated LMI for Linear Parameter-Varying Systems

Disturbance Compensator Design Based on Dilated LMI for Linear Parameter-Varying Systems

A Comprehensive Review on Control Technique and Socio-Economic Analysis for Sustainable Dynamic Wireless Charging Applications

Dynamic wireless power transfer (DWPT) has garnered significant attention as a promising technology for electric vehicle (EV) charging, eliminating the need for physical connections between EVs and charging stations. However, the improvement in power transfer efficiency is a major challenge among the research community. Different techniques are investigated in the literature to maximize power transfer efficiency. The investigations include the power electronic circuit, magnetic coupler design, compensating capacitance and control technique. Also, the investigations are carried out based on the type of wireless charging system, which is either a static or dynamic scenario. There are a good number of review articles available on the power electronic circuit and compensator design aspects of WPT. However, studies on the controller design and tracking maximum efficiency are some of the important areas that need to be reviewed. This paper provides a comprehensive review of bibliometric analysis on the DWPT technology, design procedure, and control technique to increase the power transfer and socio-economic acceptance analysis. The manuscript also provides information on the challenges and future direction of research in the field of DWPT technology.

Integral global fast terminal sliding mode control for LLC converters

Abstract The complex characteristics of full-bridge LLC converters and PFM mode of operation result in a variety of operating modes and characteristic changes at different operating frequencies, thus increasing the difficulties in small signal characteristic analysis and good compensator design. In terms of control strategy, the traditional linear controller has limited response performance under various operating conditions such as input voltage ripple perturbation, input voltage mutation, and load mutation. To obtain greater transient response performance, stronger disturbance capability, and higher input stability of the system under different operating conditions, this paper proposes a new integral global sliding mode control law for LLC converters. In contrast to conventional control methods, the proposed control strategy exhibits enhanced dynamic response capabilities in the presence of load variations. It effectively mitigates jitter issues during steady-state operation, demonstrating a superior control performance.

A compensator design and stability margin monitor for digitally controlled DC-DC converters

ABSTRACT In this paper, an automatic direct digital design approach for compensators is presented to achieve a lookup table proportional – integral – derivative controller. Additionally, a correlation-based stability margin monitor with adaptive sliding window smoothing is proposed to increase the identifiable range for bandwidth detection. The proposed automatic compensator design approach meets the expected phase margin and crossover frequency and considers limit-cycle oscillation conditions throughout the design process. The digital controller with the direct digital design was implemented on a field programmable gate array to validate the approach and alternative design capabilities. Experimental results show that the direct digital design yields a higher crossover frequency than digital redesign. The best transient response performance can be obtained if a proper integral gain is designed. The digital controller with ASWS was fabricated using the TSMC 1P6M 0.18-μm standard CMOS process. Further experimental results show that the proposed ASWS provides a significantly more accurate identified frequency response by using narrow windows at low frequencies and expansive windows at high frequencies.

Phantoms for Quantitative Body MRI: a review and discussion of the phantom value.

In this paper, we review the value of phantoms for body MRI in the context of their uses for quantitative MRI methods research, clinical trials, and clinical imaging. Certain uses of phantoms are common throughout the body MRI community, including measuring bias, assessing reproducibility, and training. In addition to these uses, phantoms in body MRI methods research are used for novel methods development and the design of motion compensation and mitigation techniques. For clinical trials, phantoms are an essential part of quality management strategies, facilitating the conduct of ethically sound, reliable, and regulatorily compliant clinical research of both novel MRI methods and therapeutic agents. In the clinic, phantoms are used for development of protocols, mitigation of cost, quality control, and radiotherapy. We briefly review phantoms developed for quantitative body MRI, and finally, we review open questions regarding the most effective use of a phantom for body MRI.

Adaptive nonlinear robust lead compensator design for a class of uncertain nonlinear systems

Adaptive nonlinear robust lead compensator design for a class of uncertain nonlinear systems

Design of digital compensators for multi-output DC-DC converters with reduced cross-regulation

ABSTRACT In the recent times, a single multi-port DC-DC converter (MPC) is highly preferred over the multiple single output DC-DC converters. Single Input Dual Output (SIDO) Buck converter with Coupled Inductors (CI) are widely employed for the reduction of multiple outputs. In this paper, the prognostic procedures to monitor MPC operating with load dynamics are discussed. The occurrence of cross-regulation during the load dynamics is suppressed by an improved digital compensator, which was specifically designed to address the cross-regulation problem. The developed digital compensation circuit is employed in the CI-SIDO Buck converter with an input of 48 V and delivering outputs of 12 V/75Watts and 24 V/125 Watts. The occurrence of cross-regulation is controlled by decoupled dual loop digital PID controller with dynamical digital compensation. A meticulous Frequency Response Analysis (FRA) with bode plot is conducted exhaustively for the derived system transfer functions. The proposed design is verified in simulation and experiments, exhibiting an enhanced results with significant suppression in cross-regulation and stability.

Complexity of CEO compensation packages

This paper examines complexity in CEO compensation contracts. We develop a measure of compensation complexity and provide empirical evidence that complexity has increased substantially over time. We document that complexity results not only from factors reflecting efficient contracting, but also from external pressures from compensation consultants, institutional investors, proxy advisors, and attempts to benchmark to peers, with these external factors having greater impact in more recent years. Examining consequences of contract complexity, we find an association with lower future firm performance that is related to the influence of external factors on compensation design. We further find this relation is partially mitigated when a contract's performance metrics are more highly correlated, consistent with information processing costs hampering decision-making. Collectively, these findings confirm concerns raised by investors and the media regarding compensation complexity and can inform boards in their design of CEO pay packages.

Show Me the Money! Supply and Demand Misalignment for Tangible Rewards in Business*

ABSTRACTIn incentive contracts, supervisors often set targets for employee performance, while employees decide the effort they are willing to exert to meet the target and earn the incentive. Both supervisors and employees make judgments about the value of incentives in terms of effort required or expended. Recent research on incentive types investigates employee effort in response to tangible and cash rewards under the premise that they may be valued differently by employees. We extend this research by investigating whether supervisors and employees make different effort‐related decisions in response to tangible and cash rewards. Specifically, relying on construal‐level theory, we predict that supervisors will favor tangible rewards relative to cash more than employees will. We conduct a lab experiment where we ask participants to take the role of either supervisor or employee. We manipulate the reward type (tangible or cash) and measure how much work supervisors demand and employees are willing to provide to obtain the reward. As predicted, we find that the tangible rewards, relative to cash, increase supervisors' target setting significantly more than employee effort levels. Our results offer implications for real‐world incentive compensation design.

Antiwindup Compensation for Unstable Rigid-Body Systems with Quantized and Saturated Inputs

It is well known that actuator saturation can cause destabilization and degradation in performance; similar problems are encountered when actuation is quantized. This study proposes the design of an antiwindup compensator for systems with actuators that are limited to a finite number of quantization levels. This combination of discrete-level actuation and saturation poses a unique antiwindup problem that has not yet been solved. To surmount this combined issue, an antiwindup compensator is proposed, which provides ultimate boundedness of the system state within a prescribed region and guarantees that the state does not stray outside a larger compact set. The use of shifted ramp functions enables a less conservative bound on the control-signal error, which yields significantly lower L2 gain bounds compared to a standard sector-bound antiwindup design approach. A numerical simulation example illustrates the effectiveness on a rigid-body system, which inspired this study.

Conditional adaptive time series compensation and control design for multi-axial real-time hybrid simulation

The structural performance of critical infrastructure during extreme events requires testing to understand the complex dynamics. Shake table testing of buildings to evaluate structural integrity is expensive and requires special facilities that can allow for the construction of large-scale test specimens. An attractive alternative is a cyber-physical testing technique known as Real-Time Hybrid Simulation (RTHS), where a large-scale structure is decomposed into physical and numerical substructures. A transfer system creates the interface between physical and numerical substructures. The challenge occurs when using multiple actuators connected with a coupler (i.e., transfer system) to create translation and rotation at the interface. Tracking control strategies aim to reduce time delay errors to create the desired displacements that account for the complex dynamics. This paper proposes two adaptive control methodologies for multi-axial real-time hybrid simulations that improve capabilities for a higher degree of coupling, boundary, complexity, and noise reduction. One control method integrates the feedback proportional derivative integrator (PID) control with a conditional adaptive time series (CATS) compensation and inverse decoupler. The second proposed control method is based on a coupled Model Predictive Control (MPC) with the CATS compensation. The performance of the proposed methods is evaluated using the virtual multi-axial benchmark control problem consisting of a steel frame as the experimental substructure. The transfer system consists of a coupler that connects two hydraulic actuators generating the translation and rotation acting at the joint. Through sensitivity analysis, parameters were tuned for the decoupler components, CATS compensation, and the control design for PID, LQG, and MPC. Comparative results among different control methods are evaluated based on performance criteria, including critical factors such as reduction in the time delay of bothactuators. The research findings in this paper improve the tracking control systems for the multi-axial RTHS of building structures subjected to earthquake loading. It provides insight into the robustness of the proposed tracking control methods in addressing uncertainty and improves the understanding of multiple output controllers that could be used in future cyber-physical testing of civil infrastructure subjected to natural hazards.

Towards optimizing canal system operations: Extremum-seeking controller design via a frequency-based control approach

This paper addresses strategies for enhancing the operational management of canal systems, aiming to reduce water losses resulting from overflows that arise due to inadequate water level control during canal operations. The study focuses on nonlinear modeling and system identification of a canal system, presenting a detailed analysis, design, and practical implementation of a frequency-based compensator. The mathematical model of the experimental canal system is derived through real-time experiments. The operational management of this experimental canal system is achieved using a compensator structure based on Bernstein polynomials. The proposed compensator parameters are refined using the extremum-seeking control algorithm, which is employed for optimizing a frequency-based cost function. The efficiency and performance of the proposed compensator compared to the cases where classical PI and two-degree-of-freedom PI with feed-forward controllers are used demonstrated through time domain and harmonic analysis plots related to the water level dynamics.

Coordination of Controllers to Development of Wide-Area Control System for Damping Low-Frequency Oscillations Incorporating Large Renewable and Communication Delay

The modern power systems incorporate high penetration of renewable is a large, composite, interconnected network with dynamic behavior. The small disturbances occurring in the system may induce low-frequency oscillations (LFOs) in the system. If the (LFOs) are not suppressed within a stipulated time, it may cause system islanding or even blackouts. Hence, it is essential to investigate the behavior of the system under various levels of disturbances and control action must be taken to damp these oscillations. The established approach to damping the LFOs is by installing power system stabilizers (PSS). PSS uses the local signals from generators to control the oscillations. The dominant source of inter-area oscillations in power systems is due to overloaded weak interconnected lines, converter-interfaced generation, and the action of the high gain exciter present in the system. Consequently, wide area control is needed to control the inter-area oscillations existent in the system. This paper developed a coordinated design of conventional PSS, static compensator, renewable converters, and wide area controller for damping the local and inter-area oscillations in renewable incorporated power systems. The performance of the developed controller is evaluated through the time domain analysis and eigenvalue analysis. A comparison of the introduced controller has been done with other standard conventional methods. The choice of input signals for the wide area controller from the wide-area measurement system is done based on the controllability index. Additionally, the location of the controller must be identified to dampen the inter-area oscillations in the system. In this paper, the controllability index is calculated to find out the highly affected wide area signals for considering it as the feedback signal to a developed controller. The location of the controller is recognized by computing the participation factor. The developed controller has experimented on renewable incorporated large study power systems when time delay and noise are present in wide area signals.

Cooperative Design of Asynchronous Controller and Dynamic Packet Dropouts Compensator for Strictly Dissipative T–S Fuzzy Markov Jump Systems

Cooperative Design of Asynchronous Controller and Dynamic Packet Dropouts Compensator for Strictly Dissipative T–S Fuzzy Markov Jump Systems

On observer compensator design for non-autonomous control semi-linear evolution equations

This paper investigates the Luenberger observer design problem for non-autonomous control semilinear evolution equations with disturbances in Banach spaces. Then, the practicalstabilization problem of the system is solved, yielding a compensator based on the Luenberger observer by using integral inequalities of the Gronwall type. Sufficient conditions of the controller and observer problem are satisfied, we show that the proposed controller with estimatedstate feedback from the proposed practical Luenberger observer will achieve global practical stabilization. We develop novel ideas and techniques, which present the further development of mathematical control theory. Furthermore, an example is given to show the applicability of our theoretical results.