در این مقاله یک روش کنترل کنندهی غیرخطی مود لغزشی برای پایدارسازی سیستمهای آشوبناک مرتبهی کسری غیرخطی با وجود نامعینی مدل و اغتشاشات خارجی طراحی گردیدهاست. ویژگی اصلی این کنترل کننده به حداقل رساندن چترینگ و همچنین همگرایی سریع به نقطهی تعادل و مقاومت در برابر نامع More
در این مقاله یک روش کنترل کنندهی غیرخطی مود لغزشی برای پایدارسازی سیستمهای آشوبناک مرتبهی کسری غیرخطی با وجود نامعینی مدل و اغتشاشات خارجی طراحی گردیدهاست. ویژگی اصلی این کنترل کننده به حداقل رساندن چترینگ و همچنین همگرایی سریع به نقطهی تعادل و مقاومت در برابر نامعینیها میباشد. برای اثبات پایداری سیستم کنترلشده بر اساس روش مستقیم تئوری لیاپانف در حالت کسری از مدل فرکانس توزیعشده استفاده شدهاست. مثالهای کاربردی و شبیهسازیهای عددی برای نشان دادن کارایی روش پیشنهادی ارائه شدهاست.
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In this paper, a robust dynamic slip mode controller for an electrical robot manipulator is presented. The control law calculates the motor voltage based on the voltage control strategy. Uncertainties are estimated using the Fourier series expansion and the cutting erro More
In this paper, a robust dynamic slip mode controller for an electrical robot manipulator is presented. The control law calculates the motor voltage based on the voltage control strategy. Uncertainties are estimated using the Fourier series expansion and the cutting error is compensated. Fourier coefficients are adjusted based on stability analysis. Also in this paper is the design of a robust controller using a new adaptive Fourier series extension. Compared to previous related works based on the Fourier series expansion, the advantage of this paper is that it provides a matching law for the main frequency of the Fourier series expansion and thus eliminates the need for trial and error in its regulation. A case study of a Scara robot powered by DC magnet electric motors. The effect of uncertainty estimation based on the Fourier series expansion is studied instead of using the sign function. The proposed method is also compared with Legendre polynomials. The simulation results confirm the robust and satisfactory performance of the proposed controller.
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This paper proposes an integral sliding mode direct power control (ISM-DPC) strategy for brushless doubly fed induction generators. Two widely applied control strategies are available for this type of generators: hysteresis-based direct power control and vector control. More
This paper proposes an integral sliding mode direct power control (ISM-DPC) strategy for brushless doubly fed induction generators. Two widely applied control strategies are available for this type of generators: hysteresis-based direct power control and vector control. Direct power control suffers from high power ripples and current distortions produced by variable switching frequency. Moreover, the tuning issues of PI controller, which are highly reliant on machine parameters and operating conditions, and necessity of a phase-locked-loop for frame alignment are accounted as limitation of these methods. The proposed integral sliding mode strategy directly controls active and reactive power to provide fast dynamic response and zero steady-state error. This method is developed in the control winding reference frame to avoid the application of PLL. A large-scale brushless doubly fed induction generator (BDFIG) is simulated to validate the effectiveness and robustness of the proposed ISM-DPC method in comparison with widely applied methods, vector control and direct power control.
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Electro-hydraulic servo systems are one of the most important control systems used in many fields such as industrial automation, numerical control machines, the oil and gas industry. Due to the non-linear behavior of hydraulic system components and the presence of vario More
Electro-hydraulic servo systems are one of the most important control systems used in many fields such as industrial automation, numerical control machines, the oil and gas industry. Due to the non-linear behavior of hydraulic system components and the presence of various uncertainties in their operation, the modeling and control of these systems face problems. In this paper, a fuzzy adaptive controller based on sliding mode control is proposed to control the position of an electrohydraulic servo system and overcome the uncertainties. The proposed robust controller results in minimal dependence on the system model. The system's stability in the presence of uncertainties has been proved by applying the Lyapunov theory and considering the time-varying nature of the uncertainties. Besides, to approximate the maximum band and the range of uncertainties, an adaptation law has been proposed for its estimation. The simulation results show the reasonable and stable performance of the proposed adaptive fuzzy controller compared to other control methods.
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In this paper, in order to reduce disturbance attenuation in the single-machine infinite-bus system a STATCOM by an improved robust back-stepping algorithm based on a particle swarm optimization approach is proposed. In the proposed approach, the adaptive back-stepping More
In this paper, in order to reduce disturbance attenuation in the single-machine infinite-bus system a STATCOM by an improved robust back-stepping algorithm based on a particle swarm optimization approach is proposed. In the proposed approach, the adaptive back-stepping method is used to construct the storage function to reduce internal and external disturbances. Also, a nonlinear controller with interference rejection feature and update of the nonlinear parameter substitution law are applied simultaneously. In this research, in order to maintain non-linearities feature, the real-time estimation of uncertain parameters, ensure robustness and insensitivity to large disturbances of the STATCOM system, the adaptive back-stepping sliding mode control method is applied in terms of error compensation design. It should be noted that the proposed controller has a large number of design parameters which affect its efficiency and performance. So, here the particle swarm optimization approach is used to determine the design parameters based on the cost function of the integral of the magnitude of the error. Finally, the simulation results are performed by MATLAB software, confirmed the better performance of the proposed optimal back-stepping sliding mode control method compared to traditional adaptive back-stepping in terms of the speed of adaptation and the response of the STATCOM system.
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This paper constructs a new complex hyper-chaotic system with attractive coexisting dynamic behaviors. We analyze the hyper-chaotic attractors, equilibrium points, Poincaré maps, Kaplan-York dimension, and Lyapunov exponent behaviors. The characteristics of hyper More
This paper constructs a new complex hyper-chaotic system with attractive coexisting dynamic behaviors. We analyze the hyper-chaotic attractors, equilibrium points, Poincaré maps, Kaplan-York dimension, and Lyapunov exponent behaviors. The characteristics of hyper-chaotic systems include higher complexity, higher parametric resistance and sensitivity to very small changes in initial conditions. We prove that the introduced hyper–chaotic system is much more complex than the similar hyper-chaotic systems, that can suitable for use in encryption and secure communication. Next, the work describes a fast terminal sliding mode controller scheme for the fast synchronization and stability of the new complex hyper–chaotic system. It is shown that by applying uncertainty to the system, both steps of the sliding mode control have finite-time convergence properties. Next, a comparison will be made between a newly designed controller and a similar. Finally, using the MATLAB simulation, the results are confirmed for the new system. The results shown that the new hyper-chaotic system with many adsorbents is much more complex than similar systems, and the proposed controller has a faster convergence response than the similar controller.
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In this paper, a new control approach for robust synchronization of chaotic systems with uncertainty, unknown parameters such as indefinite time delay and external disturbances is presented. Uncertain time delay as an important factor that increases the complexity of th More
In this paper, a new control approach for robust synchronization of chaotic systems with uncertainty, unknown parameters such as indefinite time delay and external disturbances is presented. Uncertain time delay as an important factor that increases the complexity of the control problem and overcoming it is stated in this article. By using the structure of nonlinear proportional-integral-derivative control­lers of fractional order, a sliding surface of fractional order has been introduced to design the control strategy of the said sliding mode. Then, using Lyapunov's theory, robust adaptive rules are designed in such a way that the estimation error of the unknown parameters of the fractional order system with an indefinite time delay tends to zero by the proposed control mechanism. Also, by using Lyapunov stability standard the stability analysis of the proposed robust control approach has been proved. Finally, the performance evaluation of the proposed mechanism, the synchronization of two Jerk chaotic systems with uncertainty along an indefinite time delay and disturbance, has been simulated by the presented control approach, the results of which show the robust and favorable performance of the simulation.
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According to the critical role of gas turbines in the industry, monitoring the performance of gas turbines is an important issue since it can prevent unexpected shutdowns and the serious consequent financial harms. One of the most important parts of a gas turbine is the More
According to the critical role of gas turbines in the industry, monitoring the performance of gas turbines is an important issue since it can prevent unexpected shutdowns and the serious consequent financial harms. One of the most important parts of a gas turbine is the combustion chamber. Although the internal pressure and temperature of the combustion chamber can directly affect the performance and useful life of this part, however, it is not possible to measure it directly through sensors. Therefore, estimation of pressure variable is a good choice to achieve greater performance and more relative stability comparing with the methods in which there is no access to the internal pressure of the chamber. In this research, a suitable nonlinear dynamic model with produced power and exhausted gas temperature as its outputs is chosen. Thereafter, an adaptive surface sliding observer is designed in order to estimate the combustion pressure and temperature which are the state variables of the gas turbine. Afterward, utilizing a sliding mode controller and applying the estimated states, the produced power and exhaustion gas temperature of the gas turbine is controlled. In this paper, the stability of the closed-loop system in the presence of the state observer through the Lyapunov approach is guaranteed. Finally, simulation results are provided to verify the validity and efficiency of the proposed method.
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In this paper, we investigate a hybrid controller for wheeled mobile robots in the presence of external disturbances and parametric uncertainty. Robot models include kinematic and dynamic equations of motion. In this paper, in order to reach the final position, the whee More
In this paper, we investigate a hybrid controller for wheeled mobile robots in the presence of external disturbances and parametric uncertainty. Robot models include kinematic and dynamic equations of motion. In this paper, in order to reach the final position, the wheeled moving robot must be controlled in such a way that it can follow a reference path. Many studies often use a motion control strategy for the wheeled mobile robot. In this study, the proposed control strategy has two stages including cinematic control and dynamic control. In this regard, first after introducing the kinematic model of the robot, we design a predictive controller for this part and prove it. Then, based on the nonlinear dynamic dynamics of the robot, an adaptive sliding mode dynamic controller is introduced to estimate the disturbances online, automatically adjust the gain of the control and eliminate the umbrella phenomenon completely. Then, the proposed design is analyzed and proved using Lyapanov's theory of stability. According to the proposed adaptive control law, optimal convergence and tracking performance of all signals are guaranteed and tracking errors can converge arbitrarily in finite time to the source. Simulation results have been performed to show the effectiveness of the proposed design using Matlab software.
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In this paper, a sliding mode controller with an adjustable reactive power reference value is proposed. To improve the performance of the controller in a steady-state, an Integral Sliding Mode Control is designed and used. In addition, to improve the low-voltage ride-th More
In this paper, a sliding mode controller with an adjustable reactive power reference value is proposed. To improve the performance of the controller in a steady-state, an Integral Sliding Mode Control is designed and used. In addition, to improve the low-voltage ride-through capability in the fault condition, a reactive power controller with an adjustable reference value is proposed. The performance of this control system, during the power track, is compared with two other control systems that have a fixed reference for reactive power and are based on SMC and PI controllers in 9 different fault modes. These 9 different modes include one-phase, two-phase, and three-phase short circuit faults in the sub-synchronous, synchronous, and super-synchronous mode of operation for DFIG. The proposed method has been implemented in Simulink/MATLAB software. The simulation results confirm the capability and effectiveness of the proposed control system in comparison with two other aforementioned control systems.
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This paper presents a new method for designing of power system stabilizer (PSS) based on sliding mode control (SMC) technique. The control objective is to enhance stability and improve the dynamic response of the multi-machine power system. The mathematical model of the More
This paper presents a new method for designing of power system stabilizer (PSS) based on sliding mode control (SMC) technique. The control objective is to enhance stability and improve the dynamic response of the multi-machine power system. The mathematical model of the synchronous generator is first transformed into a form that facilitates the design of nonlinear control schemes. Then, a sliding mode controller is proposed. In order to test effectiveness of the proposed scheme, simulation will be carried out to analyze the small signal stability characteristics of the system about the steady state operating condition following the change in the parameters of the system and to the disturbances. For comparison, simulation of a conventional control PSS (lead-lag compensation type) will be carried out. The main approach is to focus on the control performance which later is proven to have the degree of shorter reaching time and lower spike.
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Recently to eliminate the harmonics and improve the power factor of the power networks, much attention has been attracted to active filters. The advantages of these filters are lower volume and their better compensating characteristics than the passive filters. In conve More
Recently to eliminate the harmonics and improve the power factor of the power networks, much attention has been attracted to active filters. The advantages of these filters are lower volume and their better compensating characteristics than the passive filters. In conventional sliding mode controllers, the source current waveform is fluctuated in near to zero values. In this paper, using a new sliding technique, lower Total Harmonic Distortion (THD) in source current is obtained and the current waveform is improved. As well as, two novel control strategies for two types of active filters, VSI and CSI is proposed and then these two types of filters are compared to reduce THD value of source current.The proposed controlled strategies are simulated by MATLAB/Simulink. The Simulation results confirm that the proposed strategies reduce the THD of source current more than other strategies, and active filter based on CSI has a better performance than active filter based on VSI with a dead time area (for avoiding short circuit of the source) in high powers.
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This paper introduces and discusses a new control strategy for nonholonomic wheeled mobile robots (WMR). Robot models include kinematic and dynamic equations of motion. A barrier function adaptive terminal sliding mode control is used to control the movement of the robo More
This paper introduces and discusses a new control strategy for nonholonomic wheeled mobile robots (WMR). Robot models include kinematic and dynamic equations of motion. A barrier function adaptive terminal sliding mode control is used to control the movement of the robot. It considers sliding mode control (SMC) to deal with the dynamic model uncertainties of the chaos system, and uses a combination of SMC with an adaptive control approach to solve the upper boundaries problem of unknown model uncertainties and their estimation. Chattering is completely eliminated without over estimating the control gains by adopting an adaptive continuous barrier function in the dynamic switching function. Using the Lyapunov's stability theory, it was shown that the proposed scheme can guarantee the convergence of system states to the vicinity of the sliding surface in finite time. Additionally, the adoption of a sliding surface with a nonlinear and integral switching function resulted in removing the reaching phase of the sliding surface and yielding a controller that is robust to uncertainties from the start. The effectiveness of the proposed control method was assessed using three scenarios implemented to a Liu's uncertain chaotic system in MATLAB/Simulink environment. The obtained results confirmed the ability of the proposed approach to achieve continuous and smooth control rules for such chaotic systems. Among the main attributes of the proposed control method are its ability to completely eliminate chattering and yield a robust performance against model uncertainties and unknown external disturbances.
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The main cause of oscillation during the movement of the vehicle is the unevenness of the road. Therefore, in order to maintain the stability of the car in swing states, the suspension system plays an essential role. Therefore, the active suspension system is used to re More
The main cause of oscillation during the movement of the vehicle is the unevenness of the road. Therefore, in order to maintain the stability of the car in swing states, the suspension system plays an essential role. Therefore, the active suspension system is used to replace the conventional passive suspension system, to improve comfort and smoothness. To reduce the displacement of the spring mass in the active vehicle suspension system, a high-order sliding mode controller is proposed in this paper. Uncertainty of system parameters, nonlinear characteristic of damping and spring, load changes and unknown path disturbance are estimated by disturbance observer. The controller only needs the information of the spring mass state variables and therefore does not need separate sensors to measure the suspension mass state variables. Particle swarm optimization algorithm has been used to determine the control parameters. The efficiency of the proposed method has been shown using simulation in MATLAB software and the results have been compared with the passive suspension system.
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