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Pourseiedrezaei, Mehdi, Mohammad Bozorg et Ali Delavar-Khalafi. « Application of Two Polynomial Optimization Methods for Computing Robust Stability and Robust Performance Margins ». IFAC Proceedings Volumes 44, no 1 (janvier 2011) : 7690–95. http://dx.doi.org/10.3182/20110828-6-it-1002.02974.
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Al-Shamali, Saleh A., Haniph A. Latchman, Baowei Ji et Oscar D. Crisalle. « A Margin for Robust Stability and Robust Performance ». IFAC Proceedings Volumes 36, no 11 (juin 2003) : 335–40. http://dx.doi.org/10.1016/s1474-6670(17)35686-0.
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Abdulsada, Abdullah, et Nasir Selman. « Robust digital voltage mode control of buck converter with enhanced tracking performance ». Al-Qadisiyah Journal for Engineering Sciences 17, no 2 (30 juin 2024) : 158–64. http://dx.doi.org/10.30772/qjes.2024.145861.1076.
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The digital voltage controller of power converters is used because it has many advantages over its analog counterparts. Thus, in this paper, a controller of digital voltage mode is designed and analyzed for a non-isolated DC-DC buck converter in continuous conduction mode (CCM). First, an analog controller is designed using a Bode plot to achieve the desired stability margins in the frequency domain. Next, the analog controller is discretized using bilinear transformation with the pre-warping method. The characteristics of the discretized compensator can be maintained close to the corresponding analog compensator as long as a proper sampling time is selected. The digital control scheme is simulated with a nonlinear DC-DC buck converter model in MATLAB/Simulink to investigate the controller performance. The simulation results demonstrated the validation of the proposed digital voltage-mode control design approach. The developed digital controller eliminates DC error by tracking the reference voltage, achieving a fast transient response, maintaining specified stability margins, and effectively rejecting large disturbances.
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Gopi, Pasala, Pinni Srinivasa Varma, Ch Naga Sai Kalyan, C. V. Ravikumar, Asadi Srinivasulu, Bhimsingh Bohara, A. Rajesh, Mohd Nadhir Bin Ab Wahab et K. Sathish. « Dynamic Behavior and Stability Analysis of Automatic Voltage Regulator with Parameter Uncertainty ». International Transactions on Electrical Energy Systems 2023 (25 janvier 2023) : 1–13. http://dx.doi.org/10.1155/2023/6662355.
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This research article describes a novel optimization technique called simulink design optimization (SDO) to compute the optimal PID coefficients for an automatic voltage regulator (AVR). The time-domain performance of the proposed controller was analyzed using MATLAB/Simulation, and its performance was compared with that of water cycle algorithm, genetic algorithm, and local unimodal sampling algorithm-based PID controllers. The robustness of the proposed controller was verified by applying the disturbances to the generator field voltage and the amplifier parameter uncertainty. The studies presented in literature were discussed the AVR loop stability using the Bode plot which will not give the minimum stability margins. This study proposes a novel stability analysis called disk-based stability analysis to authenticate the stability of the AVR loop which is obtained by the classical analysis. This stability was compared with the proposed stability analysis. The MATLAB results reveal that the SDO-PID controller regulates the terminal voltage of the generator precisely, is more robust to parameter uncertainty, and is more stable than the other controllers. The maximum allowable parameter uncertainty of the amplifier model was identified as 102% of its nominal parameters. The stability margins are recognized as DGM = 10.40 dB and DPM = 56.50° for the AVR stability.
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Hasanvand, Hamed, et Mohammad Reza Zamani. « Robust control of static Var compensator-based power oscillation dampers using polynomial control in power systems ». Transactions of the Institute of Measurement and Control 40, no 5 (24 janvier 2017) : 1395–406. http://dx.doi.org/10.1177/0142331216683774.
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A static Var compensator (SVC) installed in a power transmission network can be effectively exploited to enhance the damping of low frequency electromechanical oscillations. The application of robust control theory offers more reliable and robust damping controller to achieve desired damping level considering variations in the operating conditions of power system. This paper presents a new approach to design a robust proportional-integral (PI) controller for stabilizing power system oscillations. The variability in operating conditions is captured using an interval polynomial and then, Kharitonov’s theorem is used to design the desired damping controller. The proposed method is based on plotting the stability boundary locus in the ( kp-ki) plane and then computing the stabilizing values of the parameters of a PI controller. Besides stabilization, computation of stabilizing PI controllers that achieve user specified gain margin (Gm), phase margin (Pm) and bandwidth is studied simultaneously. This novel method enables designers to make the convenient trade-off between stability and performance by choosing the proper margins and bandwidth specifications. In addition, the most appropriate stabilizing input signal is selected using Hankel singular value (HSV) and right half plane-zeros (RHP-zeros) for the SVC-based supplementary damping controller. The effectiveness and robustness of the proposed controller are demonstrated using eigenvalue analysis and time-domain simulation for a 16 machine 68-bus test system. The simulations and analysis are implemented in matrix laboratory environment and power system analysis toolbox.
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Halbe, Omkar, Tim Mehling, Manfred Hajek et Milan Vrdoljak. « Synthesis and Piloted Evaluation of Advanced Rotorcraft Response Types Using Robust Sliding Mode Control ». Journal of the American Helicopter Society 66, no 3 (1 juillet 2021) : 1–20. http://dx.doi.org/10.4050/jahs.66.032008.
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Sliding mode control (SMC) is a promising technique for robust control synthesis with desirable properties. This paper describes the synthesis and piloted evaluation of advanced helicopter response types using the SMC technique. The required closed-loop response characteristics are specified as ideal, lower order, axial transfer functions that conform to predicted level 1 handling qualities. Two-loop, full-authority, output-tracking SMC laws are then synthesized to enforce the closed-loop performance and accurately track pilot commands. Analytical proofs for SMC gain tuning are given for the closed-loop performance to remain robust to unknown but bounded uncertainties in the input channels and the effects of rotor modes on closed-loop stability. The closed-loop eigenstructure is nearly identical to the specified closed-loop performance and has good modal decoupling. Furthermore, a frequency domain analysis with a nonlinear helicopter model shows good stability margins and disturbance rejection characteristics. Finally, the paper reports on simulation testing conducted with four experimental test pilots in a rotorcraft simulation environment. The simulation results indicate improved mission task performance and handling qualities ratings and a substantial reduction in pilot workload for the SMC-based advanced response types compared to the bare-airframe responses.
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Yeh, Syh-Shiuh, et Pau-Lo Hsu. « Theory and Applications of the Robust Cross-Coupled Control Design ». Journal of Dynamic Systems, Measurement, and Control 121, no 3 (1 septembre 1999) : 524–30. http://dx.doi.org/10.1115/1.2802506.
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The cross-coupled control (CCC) has been recognized as an efficient motion controller that reduces contouring errors, but theoretical analysis of it is lacking, and there is no systematic design approach for obtaining a CCC system with guaranteed control performance. Consequently, the compensators C in CCC are commonly implemented in a PID structure and their contouring accuracy is usually degraded in real applications under different operating conditions. In an attempt to overcome the CCC design limitations described above, this paper introduces a robust CCC design based on a novel formulation: the contouring error transfer function (CETF), leading to an equivalent formulation as in the feedback control design problem. Then, methods in robust control design can be readily employed to achieve robust CCC with specified stability margins and guaranteed contouring performance. Furthermore, the proposed design has been verified as being internally stable. All provided experimental results indicate that the proposed robust CCC design consistently renders satisfactory contouring accuracy under different operating conditions.
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S. Kumar, Supanna, C. Shreesha et N. K. Philip. « Robust PID controller design for rigid uncertain spacecraft using Kharitonov theorem and vectored particle swarm optimization ». International Journal of Engineering & ; Technology 7, no 2.21 (20 avril 2018) : 9. http://dx.doi.org/10.14419/ijet.v7i2.21.11825.
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This paper presents a robust Proportional Integral Derivative controller design methodology for three axis attitude control of a rigid spacecraft with parametric uncertainty using a combination of Kharitonov theorem and vectored particle swarm optimization based approaches. A controller is designed for each of the three axes using a systematic graphical approach. Here, a plot of the stability boundary loci in the integral gain versus proportional gain parameter plane, for the specified gain and phase margins for each of the Kharitonov interval plants is used to determine the region representing the set of all PID controllers that satisfy the desired performance and stability requirements. Vectored particle swarm optimization technique is used to determine the optimized proportional and integral gain values. The spacecraft attitude control system is simulated using Matlab-Simulink tool which shows that the designed controller provides stability, robustness, good reference pointing and disturbance rejection for perturbations within the specific bounds.
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Wang, Yuan-Jay. « A Robust FOPD Controller That Allows Faster Detection of Defects for Touch Panels ». Mathematical and Computational Applications 29, no 2 (16 avril 2024) : 29. http://dx.doi.org/10.3390/mca29020029.
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This study aims to synthesize and implement a robust fractional order PD (RFOPD) controller to increase the speed at which defects in automated touch panel inspection systems (ATPISs) are detected. A three-dimensional orthogonal stage (TDOS) driven by BLDC servo motors moves the inspection pen (IP) vertically and horizontally. The dynamic equation relating the BLDC servo motor input to the tip motion is established. A touch position identification (TPI) system is used to locate the touch point rapidly. An RFOPD controller is used to actuate the BLDC servo motors and move the TDOS rapidly and accurately in three dimensions. This method displaces the IP to any specified position and shows user-defined inspection trajectories on the touch screens. The gain-phase margin tester (GPMT) and stability equation methods are exploited to schedule the RFOPD controller gain settings and to maintain the specific safety margins for the controlled system. The simulation studies show that the proposed RFOPD controller exhibits better tracking and disturbance rejection responses than a conventional PID controller. The robustness of the RFOPD-controlled ATPIS, considering unmodeled uncertainties and friction-induced disturbances, is verified through simulation and experimental studies. Several user-defined inspection patterns are used to verify performance, and the experimental results show that the proposed RFOPD controller is effective.
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Sedraoui, M., T. Amieur, R. Bachir Bouiadjra et M. Sahnoune. « Robustified fractional-order controller based on adjustable fractional weights for a doubly fed induction generator ». Transactions of the Institute of Measurement and Control 39, no 5 (16 novembre 2016) : 660–74. http://dx.doi.org/10.1177/0142331215617236.
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In this paper, a robustification method of the primary fractional controller is proposed. This novel method uses the adjustable fractional weights on the H∞ mixed-sensitivity problem. It can achieve an enhancement in both nominal performance and robust stability margins for the uncertain plants while respecting the frequency-domain constraints, such as the tracking of the set-point references, load disturbance attenuation and measurement noise suppression. The proposed robustification holds two steps; in the first step, a primary fractional controller is designed from solving the H∞ mixed-sensitivity problem that uses fixed-integer weights. In the second step, the robustified fractional controller with adjustable fractional weights is designed in order to guarantee a good compromise between the nominal performance and the robust stability not only for the nominal plant, but also for all set of the neighbouring plants. The proposed robustified fractional controller is used to control the doubly fed induction generator. Its dynamic is modelled by the unstructured output-multiplicative uncertain plant. Simulation results given by both primary and robustified fractional controllers are compared in time and frequency domains with those given by the conventional integer H∞ controller in order to validate the effectiveness of the proposed method.
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Chen, Xi, et Gang Wang. « Walking Stability Analysis of Multi-Legged Crablike Robot over Slope ». Key Engineering Materials 572 (septembre 2013) : 636–39. http://dx.doi.org/10.4028/www.scientific.net/kem.572.636.
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This paper deals with the walking stability analysis of a multi-legged crablike robot over slope using normalized energy stability margin (NESM) method in order to develop a common stabilization description method and achieve robust locomotion for the robot over rough terrains. The robot is simplified with its static stability being described by NESM. The mathematical model of static stability margin is built so as to carry out the simulation of walking stability over slope for the crablike robot that walks in double tetrapod gait. As a consequence, the relationship between stability margin and the height of the robots centroid, as well as its inclination relative to the ground is calculated by the stability criterion. The success and performance of the stability criterion proposed is verified through MATLAB simulation and real-world experiments using multi-legged crablike robot.
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S S, Janani, Saanjhree R, B. Naga Bhavika et Dr Kiran Kumar M. « THE EFFECT OF INFLATION ON SBI BANK ». INTERANTIONAL JOURNAL OF SCIENTIFIC RESEARCH IN ENGINEERING AND MANAGEMENT 08, no 12 (4 décembre 2024) : 1–6. https://doi.org/10.55041/ijsrem39452.
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The relationship between inflation and the performance of major Indian banks, particularly the State Bank of India (SBI), reveals significant insights into macroeconomic stability and banking sector resilience. High inflation affects SBI's cost structures, loan demand, and non-performing asset (NPA) rates, with adverse impacts on profitability and asset quality. Elevated inflation rates often drive the Reserve Bank of India (RBI) to raise interest rates, indirectly impacting SBI’sloan growth and deposit mobilization.Higher interest rates increase loan costs for customers, suppressing credit demand and increasing default risks. SBI also faces higher operational costs and reduced profit margins under inflationary pressures. However, the bank’s large deposit base and robust capital position offer some resilience against inflationary shocks. Additionally, SBI's adoption of advanced risk management strategies and digitalization helps mitigate inflationary impacts, though prolonged inflationary phases can still strain its financial stability. Addressing these inflation-induced challenges requires active regulatory oversight, efficient risk management, and adaptive fiscal policies to ensure SBI’s sustained growth and stability. Keywords: Inflation, State Bank of India, non-performing assets, Reserve Bank of India, banking sector resilience,macroeconomic stability
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Osuský, Jakub, et Stanislav Števo. « Multimodel Robust Control for Hydraulic Turbine ». Advances in Electrical Engineering 2014 (25 août 2014) : 1–9. http://dx.doi.org/10.1155/2014/512628.
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The paper deals with the multimodel and robust control system design and their combination based on M-Δ structure. Controller design will be done in the frequency domain with nominal performance specified by phase margin. Hydraulic turbine model is analyzed as system with unstructured uncertainty, and robust stability condition is included in controller design. Multimodel and robust control approaches are presented in detail on hydraulic turbine model. Control design approaches are compared and used for derivation of new approaches which combine advantages of both.
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He, Weiyi, Lei Ma et Shaokun Cheng. « Ripple Voltage Suppression of Dual Active Bridge Converter in Electric Locomotive Using H∞ Loop Shaping Control Method ». Journal of Physics : Conference Series 2492, no 1 (1 mai 2023) : 012031. http://dx.doi.org/10.1088/1742-6596/2492/1/012031.
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Abstract The next-generation electric locomotive drive system has the problem of double grid frequency ripple voltage in the DC side of a single-phase PWM rectifier. In this paper, the intermediate stage dual-active-bridge DC-DC converter is studied, and an H∞ loop shaping ripple voltage suppression control strategy is proposed to restrain the harmonic voltage and optimize the dynamic and robust performance of the closed-loop system. Firstly, the mathematical model of the DAB closed-loop control system with fluctuating input voltage is established. Then, based on the H∞ loop shaping control theory, the dynamic performance, the ability of ripple voltage suppression, and the robust performance of the system are analyzed in the frequency domain. According to the results, a reasonable compensator is selected to reconstruct the magnitude frequency characteristic curve of the nominal system. After reconstruction, the solution of the robust stability margin of the corrected object is transformed into the H∞ robust control problem under the coprime factor uncertainty. The suboptimal H∞ robust controller is solved to obtain the best robustness boundary of the constructed system. Finally, the H∞ loop shaping ripple voltage suppression controller is obtained by combining the H∞ controller with the compensator. The experimental environment is set up in MATLAB-Simulink software. Compared with the traditional voltage loop control method and the input voltage feedforward control method, the dynamic performance of the proposed control strategy is slightly improved, and while within the allowable robust boundaries of the system, it has better ripple voltage suppression performance. When the system magnitude frequency curve is outside the tolerant robust stability margin, the ripple voltage suppression performance fails, but the harmonic content of output voltage is still far less than the other two control methods. The experiment results also prove the correctness of the theoretical analysis and that the proposed control method is effective and proper.
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Zhou, Hongbo, Aiping Pang, Jing Yang et Zhen He. « Structured H∞ Control of an Electric Power Steering System ». Complexity 2020 (25 juillet 2020) : 1–9. http://dx.doi.org/10.1155/2020/9371327.
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Electric power steering (EPS) systems are prone to oscillations because of a very small phase angle margin, so a stable controller is required to increase the stability margin. In addition, the EPS system has parameter disturbances in the gain of the torque map under different conditions, which requires a certain degree of robustness in the control design. This paper synthesizes the multidimensional performance requirements considering the stability margin, robustness, and bandwidth of the system to form an H∞ optimization matrix with multidimensional performance output in using the structured H∞ control design. The structured H∞ controller not only retains the characteristics of traditional H∞ controllers with excellent robust performance and high stability margin but also has a lower order, which can be better applied in practice. Based on the performance requirements of the system and practical implementation, the structured H∞ controllers with different orders were designed, and the feasibility of the structured controller was confirmed through comparison and theoretical analysis.
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Abboudi, Abdelaziz, Sofiane Bououden, Mohammed Chadli, Ilyes Boulkaibet et Bilel Neji. « Observer-Based Fault-Tolerant Predictive Control for LPV Systems with Sensor Faults : An Active Car Suspension Application ». Applied Sciences 12, no 2 (11 janvier 2022) : 684. http://dx.doi.org/10.3390/app12020684.
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In this paper, an observer-based robust fault-tolerant predictive control (ORFTPC) strategy is proposed for Linear Parameter-Varying (LPV) systems subject to input constraints and sensor failures. The main objective of this work is to establish a real observer based on a virtual observer to be used to estimate both states and sensor failures of the system. The proposed virtual observer is employed to improve the observation precision and reduce the impacts of the sensor faults and the external disturbances in the LPV systems. In addition, a real observer is proposed to overcome the virtual observer margins and to ensure that all states and sensor faults of the system are properly estimated, without the need for any fault isolation modules. The proposed solution demonstrates that, using both observers, a robust fault-tolerant predictive control is established via the Lyapunov function. Moreover, sufficient stability conditions are derived using the Lyapunov approach for the convergence of the proposed robust controller. Furthermore, the proposed approach simultaneously computes the gains of the real observer and the controller from a linear matrix inequality (LMI), which is deduced from the estimation errors. Finally, the performance of the proposed approach is investigated by a simulation example of a quarter-vehicle model, and the simulation results under a sensor fault illustrate the robustness and performance of the proposed method.
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Bucz, Štefan, Alena Kozáková et Vojtech Veselý. « Robust guaranteed performance PID controller design for non-minimum phase plants ». Journal of Electrical Engineering 69, no 2 (1 mars 2018) : 117–27. http://dx.doi.org/10.2478/jee-2018-0015.
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AbstractThe paper presents a new original robust PID design method for non-minimum phase plants to achieve closed-loop performance prescribed by the process technologist in terms of settling time and maximum overshoot, respectively. The proposed design procedure has two steps: first, the uncertain system is identified using external harmonic excitation signal with frequency, second, the controller of the nominal system is designed for specified gain margin. A couple of parameters is obtained from the time domain performance specification using quadratic regression curves, the so-called performance Bparabolas so, as to simultaneously satisfy robust closed-loop stability conditions. The main benefits of the proposed method are universal applicability for systems with both fast and slow dominant dynamics as well as performance specification using time domain criteria. The proposed PID design method has been verified on a set of benchmark systems.
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Singh, Navdeep, Bhanu Pratap et Akhilesh Swarup. « Robust control design of variable speed wind turbine using quantitative feedback theory ». Proceedings of the Institution of Mechanical Engineers, Part A : Journal of Power and Energy 232, no 6 (8 janvier 2018) : 691–705. http://dx.doi.org/10.1177/0957650917751463.
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A robust control design of a three blade, horizontal axis variable speed wind turbine is developed in this paper. The variable speed wind turbine model consists of higher order nonlinear dynamics where uncertainty has been considered in the plant parameters. Quantitative feedback theory is an effective and efficient, robust control technique through which the desired specifications over a specified range of parametric uncertainty can easily be achieved in the frequency domain. The proposed robust torque and pitch control in variable speed wind turbine using quantitative feedback theory satisfy prescribed gain and phase margin, degree of tracking for the robust performance, fast convergence, noise attenuation, and input and output disturbance rejection. The advantages of the proposed robust control design are the consideration of a wide range of performance specifications and achieving effective control over an increased operating frequency range. The simulation results demonstrate the satisfactory performance of proposed quantitative feedback theory-based controller and prefilter which fulfill the necessary conditions such as robust stability and robust tracking. Further, it has been shown that the performance of the quantitative feedback theory-based controller is better than the performance with a standard wind turbine controller and also from the performance by proportional-integral controller.
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Mystkowski, Arkadiusz. « Sensitivity and Stability Analysis of Mu-Synthesis AMB Flexible Rotor ». Solid State Phenomena 164 (juin 2010) : 313–18. http://dx.doi.org/10.4028/www.scientific.net/ssp.164.313.
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The paper presents the sensitivity and stability margin analyses of the flexible rotor supported by active magnetic bearings (AMBs) with the robust optimal vibrations control. The modal representation of the rotor finite element model (FEM) is investigated. Then, the open-loop system of the AMBs flexible rotor is established and critical speed analysis due to variation of bearing stiffness is performed. For the open-loop setup, the non-collocation effect of displacement sensors and magnetic actuators due to control stability problem is considered. The frequency mode analysis of the collocation and non-collocation system is presented. Next, the -synthesis control of 4-DOF AMBs rotor is investigated. The design process of -controllers, which cover uncertainty design and performance shape by chosen weighting function is shortly described. Then, the sensitivity function is calculated and used to evaluate the AMBs rotor stability margin for the -control and the PID control. The performance of the -controller are verified in experimental tests.
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Sharma, Neha, et Rajeevan Chandel. « Variation tolerant and stability simulation of low power SRAM cell analysis using FGMOS ». International Journal of Modeling, Simulation, and Scientific Computing 12, no 04 (9 mars 2021) : 2150029. http://dx.doi.org/10.1142/s179396232150029x.
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With technology scaling, stability, power dissipation, and device variability, the impact of process, voltage and temperature (PVT) variations has become dominant for static random access memory (SRAM) analysis for productivity and failure. In this paper, ten-transistors (10T) and low power eight-transistors SRAM cells are redesigned using floating-gate MOS transistors (FGMOS). Power centric parameters viz. read power, write power, hold power and delay are the performance analysis metrics. Further, the stochastic parameter variation to study the variability tolerance of the redesigned cell, PVT variations and Monte Carlo simulations have been carried out for 10T FGMOS SRAM cell. Stability has been illustrated with the conventional butterfly method giving read static noise margin (RSNM) and write static noise margin (WSNM) metrics for read stability and write ability, respectively. A comparative analysis with standard six-transistor SRAM cell is carried out. HSPICE simulative analysis has been carried out for 32[Formula: see text]nm technology node. The redesigned FGMOS SRAM cells provide improved performance. Also, these are robust and reliability efficient with comparable stability.
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Alsubaie, Muhammad A., Mubarak KH Alhajri, Tarek S. Altowaim et Salem H. Salamah. « Robust Conditions for Iterative Learning Control in State Feedback and Output Injection Paradigm ». Journal of Control Science and Engineering 2019 (20 janvier 2019) : 1–10. http://dx.doi.org/10.1155/2019/8023730.
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A robust Iterative Learning Control (ILC) design that uses state feedback and output injection for linear time-invariant systems is reintroduced. ILC is a control tool that is used to overcome periodic disturbances in repetitive systems acting on the system input. The design basically depends on the small gain theorem, which suggests isolating a modeled disturbance system and finding the overall transfer function around the delay model. This assures disturbance accommodation if stability conditions are achieved. The reported design has a lack in terms of the uncertainty issue. This study considered the robustness issue by investigating and setting conditions to improve the system performance in the ILC design against a system’s unmodeled dynamics. The simulation results obtained for two different systems showed an improvement in the stability margin in the case of system perturbation.
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Ponce, Pedro, J. Antonio Rosales, Arturo Molina, Hiram Ponce et Brian MacCleery. « Designing a Robust Controller Using SMC and Fuzzy Artificial Organic Networks for Brushed DC Motors ». Energies 13, no 12 (15 juin 2020) : 3091. http://dx.doi.org/10.3390/en13123091.
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Electric direct-current (DC) drives based on DC motor are extremely important in the manufacturing process, so it must be crucial to increase their performance when they are working on load disturbances or the DC motor’s parameters change. Usually, several load torque suddenly appears when electric drives are operating in a speed closed-loop, so robust controllers are required to keep the speed high-performance. One of the most well-known robust strategies is the sliding mode controller (SMC), which works under discontinue operation. This controller can handle disturbances and variations in the plant’s parameters, so the controller has robust performance. Nevertheless, it has some disadvantages (chattering). Therefore, this paper proposed a fuzzy logic controller (FLC) that includes an artificial organic network for adjusting the command signal of the SMC. The proposed controller gives a smooth signal that decrements the chattering in the SMC. The stability condition that is based on Lyapunov of the DC motor is driven is evaluated; besides, the stability margins are calculated. The proposed controller is designed using co-simulation and a real testbed since co-simulation is an extremely useful tool in academia and industry allows to move from co-simulation to real implementation in short period of time. Moreover, there are several universities and industries that adopt co-simulation as the main step to design prototypes. Thus, engineering students and designers are able to achieve excellent results when they design rapid and functional prototypes. For instance, co-simulation based on Multisim leads to design directly printed circuit boards so engineering students or designers could swiftly get an experimental DC drive. The experimental results using this platform show excellent DC-drive performance when the load torque disturbances are suddenly applied to the system. As a result, the proposed controller based on fuzzy artificial organic and SMC allows for adjusting the command signal that improves the dynamic response in DC drives. The experimental response using the sliding-mode controller with fuzzy artificial organic networks is compared against an auto-tuning, Proportional-Integral-Derivative (PID), which is a conventional controller. The PID controller is the most implemented controller in several industries, so this proposal can contribute to improving manufacturing applications, such as micro-computer numerical control (CNC) machines. Moreover, the proposed robust controller achieves a superior-speed response under the whole tested scenarios. Finally, the presented design methodology based on co-simulation could be used by universities and industry for validating and implementing advanced control systems in DC drives.
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Dyer, Stephen W., Jianjun Shi, Jun Ni et Kwang-Keun Shin. « Robust Optimal Influence-Coefficient Control of Multiple-Plane Active Rotor Balancing Systems ». Journal of Dynamic Systems, Measurement, and Control 124, no 1 (17 septembre 2001) : 41–46. http://dx.doi.org/10.1115/1.1435622.
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Rotating mass imbalance causes harmful vibration of high-speed machine tools, turbomachinery, etc. Constant speed, steady-state influence coefficient control allows active balancing systems to suppress this vibration if the influence matrix is estimated accurately. An optimal strategy for multiple-plane active balancing control is presented here that improves control robustness to modeling and estimation errors. The vibration controller objectively trades off residual vibration, control effort, and control rate of change. Penalizing control effort and rate of change is shown to enhance control stability margin, with certain performance trade-offs. Experimental results illustrate the improvement in control robustness compared with traditional weighted least squares optimal control.
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Zhao, Wenshuai, Xi Wang, Yifu Long, Zhenhua Zhou et Linhang Tian. « Robust LQR Design Method for the Aero-Engine Integral Constant Pressure Drop Control Valve with High Precision ». Aerospace 10, no 5 (30 avril 2023) : 428. http://dx.doi.org/10.3390/aerospace10050428.
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The closed-loop constant pressure drop control valve is widely used in aero-engine fuel servo metering systems. However, the available constant pressure drop control valve cannot realize servo tracking without static error and, often, a high proportional gain is used to reduce the static error and improve the servo tracking performance, which reduces the stability margin. In this paper, an integral constant pressure drop control valve is designed, which consists of an integral controller and a stabilizing controller. Moreover, a robust LQR design method is proposed to complete the design task. Firstly, the controlled plant’s state–space model is derived, and the augmented model with tracking error is established based on the robust servo system design theory. Secondly, a servo controller with dual functions of integral control and stabilization control is constructed and decoupled, in which the stabilizing controller guarantees the asymptotic stability as well as the anti-disturbance performance, and the integral controller realizes the servo tracking without static error. Finally, based on the robust LQR design method, two key design parameters, including the integral control gain and the stabilization control gain, are designed to complete the design task. The simulation results indicate that, even when suffering 50 mm2 metered flow area step disturbance and 1 MPa inlet pressure step change, the designed integral constant pressure drop control valve can realize the function of servo tracking without static error. The static error is almost 0, the settling time is within 0.01 s, the overshoot is within 10%, and the phase margin is more than 55°.
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Shou, Ho Nien. « Discoid and Asymmetrical Micro-Satellite Propulsion Mode Attitude Control with Great Mass Change and without Angular Rate Sensor ». Applied Mechanics and Materials 479-480 (décembre 2013) : 753–57. http://dx.doi.org/10.4028/www.scientific.net/amm.479-480.753.
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The center of mass of the micro-satellite can offset due to fuel consumption in the course of propulsion, with the interference of external orbital environment such as gravity gradient torque and solar radiation torque. If the structural shape is discoid and asymmetrical, the attitude control may be difficult. The only solution is to design a robust controller, so that the attitude pointing of the satellite can meet the mission requirements with the interference of internal parameter perturbation and external disturbance. This study applied the robust control theory control law in the design of Formosat-3 propulsion mode attitude control, and carried out cross validation of the feasibility of the controller by time domain and frequency domain stability analyses. This study used controller as the experimental result. The time domain performance indexes (e.g., rise time, maximum overshoot and stabilization time) of the designed controller were consistent with the robust stability margin of stable performance index of frequency domain. Meanwhile, in order to reduce the weight and manufacturing cost of satellite, in the design of satellite attitude angular rate determination, the project used unscented kalman filter (UKF) algorithm, coarse sun sensor (CSS) and earth horizon sensor (EHS) as measurement components to obtain the satellite attitude without rate gyro. The research method and procedures in this study are applicable to any shaped and asymmetrical satellites with large mass variation and without angular rate sensor. The attitude sensors include three-axis magnetometer, horizon sensor, CSS as the analytic platform for stability of attitude control.
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Chen, Liuhongxu, Ping Du, Pengfei Zhan et Bo Xie. « Gait Learning for Hexapod Robot Facing Rough Terrain Based on Dueling-DQN Algorithm ». International Journal of Computer Science and Information Technology 2, no 1 (25 mars 2024) : 408–24. http://dx.doi.org/10.62051/ijcsit.v2n1.44.
Texte intégralRésumé :
In the handling of dangerous goods in explosive environments, robots are increasingly being used instead of human operators. Robots designed for operation in explosive environments are mostly equipped with tracked structures, which, due to their limited terrain adaptability, struggle to movement rugged landscapes. Hexapod robots, with their excellent maneuverability and adaptability, possess advantages in completing hazardous material handling tasks in such rugged terrains. One current challenge lies in enabling hexapod robots to autonomously adjust their gaits to cope with rugged terrain. This paper proposes a gait learning method based on the Dueling Deep Q-Network (Dueling-DQN) algorithm to address the gait adjustment problem of hexapod robots in sloped, terraced, and rugged terrain. The method combines lidar data and reinforcement learning to extract features from the lidar data to determine terrain types and foot coordinates. Finally, the Dueling-DQN algorithm and redundant phase strategy are employed to facilitate the motion of hexapod robots in these three types of rugged terrain. Simulation and prototype experiments are conducted to evaluate the Dueling-DQN algorithm's performance in terms of rewards and stability margins for the three types of terrain. During algorithm training on sloped, terraced, and rugged terrain, stable rewards and positive stability margins are achieved after approximately 490 iterations. The effectiveness and feasibility of the proposed method are further validated through Gazebo simulation and prototype experiments. In the context of movement in rugged terrain within explosive environments, the gait learning method based on the Dueling-DQN algorithm offers valuable insights into the control of hexapod robots.
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Zahra, Munazza, Meenu Baliyan, Jasmine Tan, Hooi Jin Tan, Xin Way Tan, Siti Nazatul Huda Binti Nordin et Daisy Mui Hung Kee. « Financial Performance Evaluation of Fast-Food Restaurant ». International Journal of Tourism and Hospitality in Asia Pasific 7, no 3 (19 octobre 2024) : 396–416. http://dx.doi.org/10.32535/ijthap.v7i3.3563.
Texte intégralRésumé :
This study examines McDonald's financial performance from 2019 to 2023, focusing on key financial metrics such as profitability, operational efficiency, liquidity, solvency, and cash flow. The objective is to assess McDonald's financial health and identify factors contributing to its sustained market leadership in the fast-food industry. Using descriptive statistics and regression analysis, the study evaluates McDonald's financial ratios, including operating profit margin, return on assets, inventory turnover, and current ratio, among others. The results reveal strong profitability and effective cost control, with a consistent operating profit margin and robust asset management. McDonald's liquidity is sufficient to meet short-term obligations, and its prudent debt management reflects financial stability. The company’s investment in digital transformation and operational improvements, such as streamlined inventory management and enhanced customer engagement, have further contributed to its financial resilience. In conclusion, McDonald's has demonstrated adaptability and resilience amidst external challenges, ensuring continued financial success. The study suggests that McDonald's should continue investing in digital platforms and menu innovation to meet evolving customer preferences. The implications of these findings are significant for the fast-food industry, highlighting the importance of strategic financial management in maintaining market leadership and long-term growth
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Zahra, Munazza, Meenu Baliyan, Jasmine Tan, Hooi Jin Tan, Xin Way Tan, Siti Nazatul Huda Binti Nordin et Daisy Mui Hung Kee. « Financial Performance Evaluation of Fast-Food Restaurant ». International Journal of Tourism and Hospitality in Asia Pasific 7, no 3 (20 octobre 2024) : 396–416. https://doi.org/10.32535/ijthap.v7i3.3610.
Texte intégralRésumé :
This study examines McDonald's financial performance from 2019 to 2023, focusing on key financial metrics such as profitability, operational efficiency, liquidity, solvency, and cash flow. The objective is to assess McDonald's financial health and identify factors contributing to its sustained market leadership in the fast-food industry. Using descriptive statistics and regression analysis, the study evaluates McDonald's financial ratios, including operating profit margin, return on assets, inventory turnover, and current ratio, among others. The results reveal strong profitability and effective cost control, with a consistent operating profit margin and robust asset management. McDonald's liquidity is sufficient to meet short-term obligations, and its prudent debt management reflects financial stability. The company’s investment in digital transformation and operational improvements, such as streamlined inventory management and enhanced customer engagement, have further contributed to its financial resilience. In conclusion, McDonald's has demonstrated adaptability and resilience amidst external challenges, ensuring continued financial success. The study suggests that McDonald's should continue investing in digital platforms and menu innovation to meet evolving customer preferences. The implications of these findings are significant for the fast-food industry, highlighting the importance of strategic financial management in maintaining market leadership and long-term growth
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Alyoussef, Fadi, Ibrahim Kaya et Ahmad Akrad. « Robust PI-PD Controller Design : Industrial Simulation Case Studies and a Real-Time Application ». Electronics 13, no 17 (24 août 2024) : 3362. http://dx.doi.org/10.3390/electronics13173362.
Texte intégralRésumé :
PI-PD controllers have superior performance compared to traditional PID controllers, especially for controlling unstable and integrating industrial processes with time delays. However, computing the four tuning parameters of this type of controller is not an easy task. Recently, there has been significant interest in determining the tuning rules for PI-PD controllers that utilize the stability region. Currently, most tuning rules for the PI-PD controller are presented graphically, which can be time-consuming and act as a barrier to their industrial application. There is a lack of analytical tuning guidelines in the literature to address this shortfall. However, the existing analytical tuning guidelines do not consider a rigorous design approach. This work proposes new robust analytical tuning criteria based on predefined gain and phase margin bounds, as well as the centroid of the stability region. The proposed method has been tested using various simulation studies related to a DC–DC buck converter, a DC motor, and a heat exchanger. The results indicate that the proposed tuning rules exhibit strong performance against parameter uncertainty with minimal overshoots. Furthermore, the suggested technique for simultaneous control of yaw and pitch angles has been tested in a real-time application using the twin rotor multi-input multi-output system (TRMS). Real-time results indicate that, compared to other methods under investigation, the suggested approach provides nearly minimal overshoots.
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Zadehbbagheri, Mahmoud, Rahim Ildarabadi et Tole Sutikno. « A unified power flow controller-based robust damping controller considering time delay in electrical power systems ». Indonesian Journal of Electrical Engineering and Computer Science 31, no 3 (1 septembre 2023) : 1295. http://dx.doi.org/10.11591/ijeecs.v31.i3.pp1295-1310.
Texte intégralRésumé :
Nowadays, different power systems are connected to each other due to technical and economic reasons and form a complex developed network. Such networks measure and send system data to decision-making centers for control and protection. This information transmission is accompanied by a delay and causes the performance of the system’s damping controllers to be affected. To improve power system dynamic stability, the supplementary controller in flexible alternating current transmission system (FACTS) devices is designed to account for information transmission delays. In these methods, to increase the controllability and observability of the inter-area mode, the remote signals extracted from the wide area measurement system (WAMS) are used as the input of the modulator. WAMS systems’ time delay reduces power system stability and even causes instability, so it’s crucial to find the maximum delay margin that ensures stability. Therefore, it is necessary to carefully study the role of FACTS tools in stabilizing the power system and damping interregional fluctuations, considering the delay. This research shows that supplementary controller design can dampen frequency and load angle fluctuations in multi-zone power systems despite information transmission delays. The method works in power system analysis toolbox (PSAT) simulation and MATLAB programming.
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Srivastava, Srikant, P. N. Dwivedi et D. M. Vinod Kumar. « 3 Loop Structure based Fuel Flow Controller Design for Robust Operation of Ducted Ramjet Rocket ». Defence Science Journal 71, no 4 (1 juillet 2021) : 571–77. http://dx.doi.org/10.14429/dsj.71.16397.
Texte intégralRésumé :
This paper is about the designing of 3-loop structure based fuel flow controller (FFC) for efficient operation of supersonic ramjet based propulsion system. The main objective of the control design is to vary appropriately the engine controllable parameters (throttle value area) such that commanded thrust is achieved by ramjet engine without endangering the engine stability and performance. Various factors such as combustion-intake interaction, atmospheric disturbance and other flight conditions have a significant impact on the air intake operation which lead to effect on engine performance. Due to above effect, intake un-start and buzzing phenomena can occur due to back pressure fluctuation and it disturb the intake pressure recovery and air mass flow rate. So, back pressure based extra loop introduce in 2-loop FFC design to have tight control on back pressure margin for smooth and efficient operation of air intake without need of extra hardware.
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Pham, Duc-Anh, et Seung-Hun Han. « Critically Leveraging Theory for Optimal Control of Quadrotor Unmanned Aircraft Systems ». Applied Sciences 14, no 6 (13 mars 2024) : 2414. http://dx.doi.org/10.3390/app14062414.
Texte intégralRésumé :
In the dynamic realm of Unmanned Aerial Vehicles (UAVs), and, more specifically, Quadrotor drones, this study heralds a ground-breaking integrated optimal control methodology that synergizes a distributed framework, predictive control, H-infinity control techniques, and the incorporation of a Kalman filter for enhanced noise reduction. This cutting-edge strategy is ingeniously formulated to bolster the precision of Quadrotor trajectory tracking and provide a robust countermeasure to disturbances. Our comprehensive engineering of the optimal control system places a premium on the accuracy of orbital navigation while steadfastly ensuring UAV stability and diminishing error margins. The integration of the Kalman filter is pivotal in refining the noise filtration process, thereby significantly enhancing the UAV’s performance under uncertain conditions. A meticulous examination has disclosed that, within miniature Quadrotors, intrinsic forces are trivial when set against the formidable influence of control signals, thus allowing for a streamlined system dynamic by judiciously minimizing non-holonomic behaviors without degrading system performance. The proposed control schema, accentuated by the Kalman filter’s presence, excels in dynamic efficiency and is ingeniously crafted to rectify any in-flight model discrepancies. Through exhaustive Matlab/Simulink simulations, our findings validate the exceptional efficiency and dependability of the advanced controller. This study advances Quadrotor UAV technology by leaps and bounds, signaling a pivotal evolution for applications that demand high-precision orbital tracking and enhanced noise mitigation through sophisticated nonlinear control mechanisms.
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Maity, Arnab, et Radhakant Padhi. « Robust control design of an air‐breathing engine for a supersonic vehicle using backstepping and UKF ». Asian Journal of Control 19, no 5 (6 mars 2017) : 1710–21. http://dx.doi.org/10.1002/asjc.1488.
Texte intégralRésumé :
AbstractThis paper presents an efficient robust control design approach for an air‐breathing engine for a supersonic vehicle using the Lyapunov stability theory based nonlinear backstepping control, augmented with unscented Kalman filter (UKF). The primary objective of the control design is to ensure that the thrust produced by the engine tracks the commanded thrust by regulating the fuel flow to the combustion chamber. Moreover, as the engine operates in a supersonic range, an important secondary objective is to manage the shock wave location in the intake for maximum pressure recovery with adequate safety margin by varying the throat area of the nozzle simultaneously. To estimate the states and parameters as well as to filter out the process and sensor noises, a UKF has been incorporated for robust output feedback control computation. Furthermore, independent control designs for the actuators have been carried out to assure satisfactory performance of the engine. Additionally, a guidance loop is designed to generate a typical flight trajectory of the representative vehicle using a nonlinear suboptimal input constrained model predictive static programming formulation for testing the performance of the engine. Simulation results clearly indicate quite successful robust performance of the engine during both climb and cruise phases.
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Vavilala, Sateesh K., et Vinopraba Thirumavalavan. « Analytical design of the fractional order controller and robustness verification ». IAES International Journal of Robotics and Automation (IJRA) 10, no 1 (1 mars 2021) : 10. http://dx.doi.org/10.11591/ijra.v10i1.pp10-23.
Texte intégralRésumé :
<div data-canvas-width="397.2227827050999">This paper proposes a fractional order controller (FOC) for the level control problem of the coupled tank system, using the desired time domain specifications. The coupled tank system is used in the chemical industries for the storage and mixing of liquids. The FOC is designed analytically using the direct synthesis method. In the direct synthesis method, the Bode's ideal loop transfer function is chosen as the desired transfer function. Bode's loop transfer function has the advantages like robustness to system gain variations, constant phase and very high gain margin. Performance of the proposed controller is compared with the state of the art literature. Simulation results showed that the proposed controller has the least peak overshoot. The robust performance of the proposed controller is also the best. Robust stability of the system with the proposed controller is verified, and the system is found to be robustly stable.</div>
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Cappo, Mike, Glenn De'ath, Steve Boyle, James Aumend, Roland Olbrich, Frank Hoedt, Colton Perna et Gregg Brunskill. « Development of a robust classifier of freshwater residence in barramundi (Lates calcarifer) life histories using elemental ratios in scales and boosted regression trees ». Marine and Freshwater Research 56, no 5 (2005) : 713. http://dx.doi.org/10.1071/mf04218.
Texte intégralRésumé :
Field and experimental studies showed that solution-based analysis of scales could be used to discriminate the long-term freshwater residents in the coastal fishery for catadromous barramundi. A new, robust classification technique was developed using boosted regression trees (MART) and its performance was compared with traditional linear discriminant analysis (LDA). The non-parametric MART had errors 33–81% less than LDA, and could account for non-linear relationships and interactions among elemental ratios. The best model used Sr : Ca, Ba : Ca, Fe : Ca and Mn : Ca in scales as predictors of salinity regime. Analysis of scales collected repeatedly from sub-adult fish of known environmental history showed the MART classifier could identify fish of freshwater origin until at least 10 months residence in seawater, and possibly several years, but scale growth rate could affect the temporal stability of the classifier after that time. The experiment indicated an approximate fourfold rise in Sr : Ba ratios in new scale margins, which were strongly classified by the MART as coming from saltwater fish, but inner scale sections of the same scales were still correctly classified as coming from freshwater fish. We conclude that solution-based elemental analyses of whole scales, and also annuli within scales, could offer a cost-effective, non-destructive technique to help understand the mechanisms causing enhanced year-class strength following high freshwater outflows.
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Zhou, Liufei, Xianjie Shao, Honggang Gu, Xu Chen, Haihong Wang et Zhuqing Xu. « P‐1.10 : Robust Amorphous IGZO Integrated Gate Driver Circuit for Ultra Large TFT‐LCD Applications ». SID Symposium Digest of Technical Papers 54, S1 (avril 2023) : 468–71. http://dx.doi.org/10.1002/sdtp.16334.
Texte intégralRésumé :
Recently, a‐IGZO TFTs have attracted considerable attention for ultra large‐sized and ultra high‐resolution display due to high mobility and good uniformity. The life‐time of integrated gate driver is mainly determined by the stability of low‐level maintaining and pull‐up TFTs, which always experience severe performance degradation after a long time operation. In this paper, a robust a‐IGZO integrated gate driver with dual lowlevel maintaining units is proposed and fabricated for ultra large‐sized and high resolution TFT‐LCD applications. The simulation and BTS measurement results demonstrate that proposed a‐IGZO gate driver has a large VTH shift margin, which contributes to extended life‐time of circuit operation.
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Verma, Vishwas, Gursharanjit Singh et AM Pradeep. « The effect of inlet distortion on low bypass ratio turbofan engines ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 234, no 8 (2 mars 2020) : 1395–413. http://dx.doi.org/10.1177/0954410020909190.
Texte intégralRésumé :
Inlet flow non-uniformity, commonly known as inflow distortion, has been a long-standing problem in the history of gas turbine engines. Distortion can be present in the form of total pressure, total temperature or inflow incidence or any combinations of these. The search for better and robust performance requires engines that can sustain a large amount of inlet distortion without considerable loss in the thrust. In the present paper, the effect of total pressure distortion on a single-stage compressor and low bypass ratio fans are studied. Distortion near hub and tip in the form of step radial total pressure profiles is imposed at far upstream of the rotor leading edge. A systematic approach to qualitatively predict the performance maps in the presence of these distortions is discussed. Further, two extents of total pressure distortion are explored for constant inlet distortion intensity. Hub distortion is found to increase the stability margin, whereas tip distortion reduces it. On extending the distortion extent, hub distortion drastically reduces the stability margin, whereas a comparatively lower reduction in stability margin with tip distortion is observed. The critical distortion limit is observed by varying the inlet distortion extent. Also, it is found that downstream ducts in the bypass axial fan do not interact with the upstream fan. This can be exploited to perform independent simulations of the core engine from low bypass ratio fans. Hub distortion is found to drastically affect the duct performance owing to the presence of thicker upstream inlet boundary layer.
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Ayodele, T. R. « Comparative Assessment of SVC and TCSC Controllers on the Small Signal Stability Margin of a Power System Incorporating Intermittent Wind Power Generation ». Journal of Wind Energy 2014 (11 décembre 2014) : 1–12. http://dx.doi.org/10.1155/2014/570234.
Texte intégralRésumé :
Wind power is highly variable due to the stochastic behavior of wind speeds. This intermittent nature could excite the electromechanical modes resulting in the small signal instability of a power system. In this study, the performance of static VAR compensation (SVC) and thyristor controlled series capacitor (TCSC) controllers in the damping of electromechanical modes is analyzed and compared. The study employs probabilistic modal analysis method using Monte Carlo simulation and Latin hypercube sampling techniques. Various scenarios are created to get insight into the study. The results obtained from the modal analysis are verified by using the time-domain simulation. Some of the key results show that SVC is more robust in the damping of electromechanical modes compared to TCSC. The result also reveals that allocation of power system stabilizer (PSS) using probabilistic method is more effective and robust compared to deterministic approach.
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Bokam, Jagadish Kumar, Naresh Patnana, Tarun Varshney et Vinay Pratap Singh. « Sine Cosine Algorithm Assisted FOPID Controller Design for Interval Systems Using Reduced-Order Modeling Ensuring Stability ». Algorithms 13, no 12 (1 décembre 2020) : 317. http://dx.doi.org/10.3390/a13120317.
Texte intégralRésumé :
The focus of present research endeavor was to design a robust fractional-order proportional-integral-derivative (FOPID) controller with specified phase margin (PM) and gain cross over frequency (ωgc) through the reduced-order model for continuous interval systems. Currently, this investigation is two-fold: In the first part, a modified Routh approximation technique along with the matching Markov parameters (MPs) and time moments (TMs) are utilized to derive a stable reduced-order continuous interval plant (ROCIP) for a stable high-order continuous interval plant (HOCIP). Whereas in the second part, the FOPID controller is designed for ROCIP by considering PM and ωgc as the performance criteria. The FOPID controller parameters are tuned based on the frequency domain specifications using an advanced sine-cosine algorithm (SCA). SCA algorithm is used due to being simple in implementation and effective in performance. The proposed SCA-based FOPID controller is found to be robust and efficient. Thus, the designed FOPID controller is applied to HOCIP. The proposed controller design technique is elaborated by considering a single-input-single-output (SISO) test case. Validity and efficacy of the proposed technique is established based on the simulation results obtained. In addition, the designed FOPID controller retains the desired PM and ωgc when implemented on HOCIP. Further, the results proved the eminence of the proposed technique by showing that the designed controller is working effectively for ROCIP and HOCIP.
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Wei, Wei, Xiaofang Wei, Min Zuo, Tao Yu et Yan Li. « Seizure control in a neural mass model by an active disturbance rejection approach ». International Journal of Advanced Robotic Systems 16, no 6 (1 novembre 2019) : 172988141989015. http://dx.doi.org/10.1177/1729881419890152.
Texte intégralRésumé :
A closed-loop neuromodulation automatically adjusts stimuli according to brain response in real time. It is viewed as a promising way to control medically intractable epilepsy. A suitable closed-loop modulation strategy, which is robust enough to unknown nonlinearities, dynamics, and disturbances, is in great need in the clinic. For the specialization of epilepsy, the Jansen’s neural mass model is utilized to simulate the undesired high amplitudes epileptic activities, and active disturbance rejection control is designed to suppress the high amplitudes of epileptiform discharges. With the help of active disturbance rejection control, closed-loop roots of the system are far from the imaginary axis. Time domain response shows that active disturbance rejection control is able to control seizure no matter whether disturbances exist or not. At the same time, frequency domain response presents that enough stability margins and a broader range of tunable controller parameters can be obtained. Stable regions have also been presented to provide guidance to choose the parameters of active disturbance rejection control. Numerical results show that, compared with proportional-integral control, more accurate modulation with less energy can be achieved by active disturbance rejection control. It confirms that the active disturbance rejection control-based neuromodulation solution is able to achieve a desired performance. It is a promising closed-loop neuromodulation strategy in seizure control.
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Li, Yajie, et Wei Li. « Discrete Event-Triggered Robust Fault-Tolerant Control for Nonlinear Networked Control Systems withα-Safety Degree and Actuator Saturation ». Mathematical Problems in Engineering 2015 (2015) : 1–17. http://dx.doi.org/10.1155/2015/590598.
Texte intégralRésumé :
This paper deals with the discrete event-triggered robust fault-tolerant control problem for uncertain nonlinear networked control systems (NNCSs) withα-safety degree. A discrete event-triggered communication scheme (DETCS) is initially proposed, and a closed-loop fault model is subsequently established for NNCSs with actuator saturation under the DETCS. Based on an appropriately constructed delay-dependent Lyapunov–Krasovskii function, sufficient conditions are derived to guarantee the asymptotic stability of NNCSs under two different event-triggered conditions and are established as the contractively invariant sets of fault tolerance withα-safety degree. Furthermore, codesign methods between the robust fault-tolerant controller and event-triggered weight matrix are also proposed in terms of linear matrix inequality. The simulation shows that the resultant closed-loop fault NNCSs possesses a high safety margin, and an improved dynamic performance, as well as a reduced communication load. A comparative analysis of the two event-triggered conditions is discussed in the experiment section.
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Romero, Charlotte, Mark Anthony N. Polinar et Alexander Franco A. Delantar. « Financial Performance among Selected Liquified Petroleum Gas (LPG) Retail Stores in Talisay City, Cebu ». International Journal of Multidisciplinary : Applied Business and Education Research 5, no 9 (23 septembre 2024) : 3482–91. http://dx.doi.org/10.11594/ijmaber.05.09.07.
Texte intégralRésumé :
The Liquified Petroleum Gas (LPG) sector plays a noteworthy part in the local economy, supplying essential energy resources for residential and commercial use. The COVID-19 pandemic has brought massive distractions that significantly affect the financial performance of companies, regardless of the sector they belong to, and this sector is not exempted. This study examined the financial performance of these LPG retail stores in Talisay City, Cebu, to know if they recovered financially, particularly in recent economic downturns and market forces. After examining the financial data for the years 2022 and 2023 using the identified financial ratios, the authors found that all participating LPG retail stores showed a positive financial performance in terms of their net profit margin, current ratio, debt-to-equity, asset turnover, and cash flow to debt ratios. This implies that LPG retail stores operate efficiently, maintain robust profitability, manage financial obligations correctly, and ensure sufficient liquidity. Additionally, it can give owners a positive perspective on the growth and stability in Talisay City, Cebu.
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Zhu, Rusong, Guofu Yin, Gengsheng Tang, Hai Wang et Shuangxi Zhang. « Temperature trajectory control of cryogenic wind tunnel with robust L1 adaptive control ». Transactions of the Institute of Measurement and Control 40, no 13 (9 octobre 2017) : 3675–89. http://dx.doi.org/10.1177/0142331217728569.
Texte intégralRésumé :
Temperature control in a cryogenic wind tunnel is the key to realizing finely controlled Reynolds number close to true flight. This study deploys the L1 adaptive control methodology to ensure the total temperature profile of the cryogenic wind tunnel tracks a specified reference trajectory. After introducing a non-linear model of a cryogenic wind tunnel and a linear temperature model, a linear–quadratic–Gaussian (LQG) controller is implemented as the baseline controller. The L1 adaptive controller with piecewise constant adaptive law is used as an augmentation to the baseline controller to cancel the matched and unmatched uncertainties within the actuator’s bandwidth. By introducing two modifications to the standard L1 adaptive controller, which are the transportation delay modelling in the state predictor and the non-linear state dependent filter, the L1 adaptive controller improves the performance of the baseline controller in the presence of uncertainties in temperature control, guaranteeing proper stability and delay margin. The simulation results and analysis demonstrate the effectiveness of the proposed control architecture. The main contribution of this paper lies in the first applications of L1 adaptive control to the wind tunnel control problem and the non-linear state dependent filter in L1 adaptive control structure.
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Oni, Oluwafemi Emmanuel, Andrew G. Swanson et Rudiren Pillay Carpanen. « Impact of LCC–HVDC multiterminal on generator rotor angle stability ». International Journal of Electrical and Computer Engineering (IJECE) 10, no 1 (1 février 2020) : 22. http://dx.doi.org/10.11591/ijece.v10i1.pp22-34.
Texte intégralRésumé :
<span>Multiterminal High Voltage Direct Current (HVDC) transmission utilizing Line Commutated Converter (LCC-HVDC) technology is on the increase in interconnecting a remote generating station to any urban centre via long distance DC lines. This Multiterminal-HVDC (MTDC) system offers a reduced right of way benefits, reduction in transmission losses, as well as robust power controllability with enhanced stability margin. However, utilizing the MTDC system in an AC network bring about a new area of associated fault analysis as well as the effect on the entire AC system during a transient fault condition. This paper analyses the fault current contribution of an MTDC system during transient fault to the rotor angle of a synchronous generator. The results show a high rotor angle swing during a transient fault and the effectiveness of fast power system stabilizer connected to the generator automatic voltage regulator in damping the system oscillations. The MTDC link improved the system performance by providing an alternative path of power transfer and quick system recovery during transient fault thus increasing the rate at which the system oscillations were damped out. This shows great improvement compared to when power was being transmitted via AC lines.</span>
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Yfoulis, Christos, Simira Papadopoulou et Spyridon Voutetakis. « Robust Linear Control of Boost and Buck-Boost DC-DC Converters in Micro-Grids with Constant Power Loads ». Energies 13, no 18 (15 septembre 2020) : 4829. http://dx.doi.org/10.3390/en13184829.
Texte intégralRésumé :
Power distribution systems nowadays are highly penetrated by renewable energy sources, and this explains the dominant role of power electronic converters in their operation. However, the presence of multiple power electronic conversion units gives rise to the so-called phenomenon of Constant Power Loads (CPLs), which poses a serious stability challenge in the overall operation of a DC micro-grid. This article addresses the problem of enhancing the stability margin of boost and buck-boost DC-DC converters employed in DC micro-grids under uncertain mixed load conditions. This is done with a recently proposed methodology that relies on a two-degree-of-freedom (2-DOF) controller, comprised by a voltage-mode Proportional Integral Derivative (PID) (Type-III) primary controller and a reference governor (RG) secondary controller. This complementary scheme adjusts the imposed voltage reference dynamically and is designed in an optimal fashion via the Model Predictive Control (MPC) methodology based on a specialized composite (current and power) estimator. The outcome is a robust linear MPC controller in an explicit form that is shown to possess interesting robustness properties in a wide operating range and under various disturbances and mixed load conditions. The robustness and performance of the proposed controller/observer pair under steady-state, line, and mixed load variations is validated through extensive Matlab/Simulink simulations.
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Saha, Debashis, Prodip Chandra Bishwas et Md Mustofa Ahmed Sumon. « Investigating the Market Interest Rate on Commercial Banks Financial Performance in Bangladesh ». Indian-Pacific Journal of Accounting and Finance 5, no 1 (1 janvier 2021) : 3–12. http://dx.doi.org/10.52962/ipjaf.2021.5.1.118.
Texte intégralRésumé :
The banking sector is the most vital partner of development for countries' economies. It has a remarkable contribution to the country's Gross Domestic Product. This study investigates the relationship between the market interest rate and commercial banks' financial performance. As Bangladesh's banking industry is growing, it is vital to maintain a more robust profitability level for its financial stability and soundness. Banks have some determinants that have a significant impact on their performance. The convenience sampling method is used to select the targeted sample. The study includes the time series data of eight years of fifteen commercial banks listed on the Dhaka Stock Exchange in Bangladesh. Multiple variable linear regression and correlation analysis are performed to examine the relationship of market interest rate with banks' profitability with statistical software, IBM SPSS version 25, and Microsoft excel. The study explored that the market interest rate has a significant positive impact on banks' profitability. It is also found that the lending rate and interest rate spread are significantly correlated with the banks' financial performance. The study recommended that banks make their investment to make a higher profit margin to enhance their management and financial soundness efficiency.
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Saavedra, Alvaro Christian Montaño, Walter Barra Junior, Renan Landau Paiva de Medeiros, Carlos Roozembergh Junior et Alan Sovano Gomes. « Experimental Evaluation of the Robust Controllers Applied on a Single Inductor Multiple Output DC-DC Buck Converter to Minimize Cross Regulation Considering Parametric Uncertainties and CPL Power Variations ». Energies 17, no 14 (9 juillet 2024) : 3359. http://dx.doi.org/10.3390/en17143359.
Texte intégralRésumé :
This paper presents two control design strategies for voltage regulation in a single inductor dual-output DC-DC buck converter system. Based on a nominal multiple input multiple output plant model and performance requirements, both a Linear Quadratic Regulator and a Decoupled PI control law are designed to control the power converter system under parametric uncertainties such as voltage source variation, constant power load variation, and load resistance variation. Therefore, the converter can cascade operation, which may cause the undesired effects of voltage oscillation and reduce the system’s stability margin. The control performance was assessed under both the uncertainties of resistive loading and the power variation in a constant power load. A single inductor dual-output DC-DC buck converter board was developed for experimental tests. The experimental results show that the Linear Quadratic Regulator strategy, compared to the PI strategy, presented a robust performance in the presence of parametric uncertainties in the resistive load-bearing; however, it was sensitive to uncertainties due to the presence of constant power loads.
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Abu-Seada, H. F., W. M. Mansor, F. M. Bendary, A. A. Emery et M. A. Moustafa Hassan. « Application of Particle Swarm Optimization in Design of PID Controller for AVR System ». International Journal of System Dynamics Applications 2, no 3 (juillet 2013) : 1–17. http://dx.doi.org/10.4018/ijsda.2013070101.
Texte intégralRésumé :
This paper presents a method to get the optimal tuning of Proportional Integral Derivative (PID) controller parameters for an AVR system of a synchronous generator using Particle Swarm Optimization (PSO) algorithm. The AVR is not initially robust to variations of the power system parameters. Therefore, it was necessary to use PID controller to increase the stability margin and to improve performance of the system. Fast tuning of optimum (PID) controller parameter yield high quality solution. New criteria for time domain performance evaluation was defined. Simulation for comparison between the proposed method and Ziegler-Nichols method is done. The proposed method was indeed more efficient also. The terminal voltage step response for AVR model will be discussed in different cases and the effect of adding rate feed back stabilizer to the model on the terminal voltage response. Then the rate feedback will be compared with the proposed PID controller based on use of (PSO) method to find its coefficients. Different simulation results are presented and discussed.
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Aleksandrov, A. G. « Stability margins and robust stability ». Journal of Computer and Systems Sciences International 49, no 6 (décembre 2010) : 862–71. http://dx.doi.org/10.1134/s1064230710060043.
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Verma, Vivek, Sachin Kumar et Apurva Anand. « Optimizing dynamic response and stability of pressure-controlled swash plate type axial piston pump ». Indonesian Journal of Electrical Engineering and Computer Science 37, no 2 (1 février 2025) : 771. http://dx.doi.org/10.11591/ijeecs.v37.i2.pp771-780.
Texte intégralRésumé :
The main objective of the paper is to explore the role of lead-lag compensators in improving the performance of control systems for variable delivery hydraulic axial piston pumps (VAPP). These compensators offer a range of benefits, including stability enhancement, transient response optimization, frequency response modification, disturbance rejection, and robustness improvement. A mathematical model of the hydro-mechanical system is developed, and the transfer function for the dynamic system is established. The simulation of the model with lead-lag compensator significantly enhanced the phase margin to 55.7<sup>0</sup> and gain margin to 12.3 dB ensuring robust control for pressure-controlled VAPP, whereas the uncompensated system is marginally stable. The compensated system exhibits better transient and steady-state response. The optimized lead-lag compensated system achieves a maximum percentage overshoot of 12.1% and a settling time of 1.95 sec. This is a substantial improvement compared to the uncompensated system with a maximum % overshoot of 20.5% and a settling time of 2.39 sec. The improved response tends to induce greater damping (ζ) in the compensated system from 0.015 to 0.108 and increases leakage coefficient (K) from 3.38×10<sup>-12</sup> m<sup>3</sup>/Pa.s to 24.34×10<sup>-12</sup> m<sup>3</sup>/Pa.s. Optimized lag-lead compensator ensures stability, responsiveness adapting effectively to dynamic operating conditions of VAPP for aerospace application.