Sharif Digital Repository

In this paper, a robust sliding mode control for a flexible transmission system is presented. This system has two very oscillatory vibration modes subject to large load variation which makes the control of it be difficult. A set of design specification in time domain is to be met by a single controller on each of the three main plant models. Furthermore the tracking problem in the presence of disturbance and load variation is investigated. Results show good performance of the proposed controller. In this approach, in order to estimate the hidden states of the flexible transmission system, an observer based on sliding mode control is used. © 2004 IEEE  

The robust fuzzy multimodel control as a potential tool to control the complex systems is presented in this paper. The main idea in multimodel controllers is to identify the best model of system at any instant and apply the appropriate control input to it. Classical multimodel controller works based on switching and tuning, while fuzzy logic is used in construction of fuzzy multimodel controller. The basic control signal for each model is calculated using the sliding mode control and the final control input is inferred as the weighted average of the local control inputs. A new algorithm is proposed in order to use the fuzzy multimodel control for time variant linear systems. To show the... 

Three different controllers, i.e., active controller, nonlinear controller, and active sliding mode controller are designed and examined for the synchronization of pairs of three different chaotic systems, i.e., Chen, Lü, and Lorenz. The synchronizing methods are then compared from various point of views including synchronizing error variance, convergence time, control effort, maximum and minimum values of the control signal. Our results indicate that the nonlinear controller synchronizes pairs of the different chaotic systems generally better than two other controllers according to the defined criteria. © 2006 Elsevier B.V. All rights reserved  

In this paper, a new form of generalized nonsingular fast terminal sliding mode control approach is proposed to provide the finite time tracking in connected chain of double integrator nonlinear systems subjected to additive bounded unknown uncertainties, disturbances, and internal interactions. The proposed approach presents an adjustable finite time for achieving the tracking goal which is a summation of two separate tunable times including finite reaching time and finite settling time. Tuning of the total finite time is done by adjusting arbitrary parameters in the control inputs and sliding surfaces. The high frequency switching of the control method is removed by applying a second order... 

This paper focuses on the sliding mode control which incorporates a fuzzy tuning technique. In this scheme, first, a control input based on classical sliding mode control is designed. Then, for performance enhancement and chattering elimination, an additional fuzzy control term is used together with the control signal. Furthermore the Lyapunov stability method is used to prove the asymptotic convergence of control strategies. To illustrate the usefulness of the proposed approach, classical and fuzzy sliding mode control are both applied to a flexible transmission system. The results verify the validity of the proposed control scheme. © 2004 IEEE  

An adaptive fuzzy sliding mode control (AFSMC) for uncertain dynamic systems is presented in this paper. Chattering problem in classical sliding mode control (CSMC) is highly undesirable because it may excite unmodeled high frequency plant dynamics and leads to unforeseen instabilities. The proposed approach in this paper completely eliminates the chattering by using adaptive fuzzy system to calculate continuous control gain vector instead of discontinuous one in classical sliding mode control. Mathematical proof for the stability and the convergence of the system is also presented to show its validity theoretically. The proposed approach and the classical sliding mode control are both... 

Using the combination of fuzzy clustering estimation and sliding mode control, a technique for controlling the magnetic levitation (ML) systems is introduced. This technique is applied to an experimental setup of an ML system for investigating the method derived. The system considered, is a symmetric rotor supported by a cantilever load cell beam and excited by only one electromagnet of a 4-pole magnetic bearing setup. After demonstrating the experimental setup instruction and the specifications of its parts, the clustering, and the sliding mode control methods are explained briefly, then the quality of implementing the techniques to the setup is described step by step. Finally, the results... 

The problem of spacecraftformation control and reconfiguration for halo orbit around the second libration point (L2) of the Sun-Earth Three Body (TB) system is investigated. Station keeping, reconfigu-ration and precision formation control of spacecrafts on halo orbits are performed via the use of the nonlinear Integral Sliding Mode (ISM) method as well as the optimal closed loop Linear Quadratic Regulator(LQR) approach. In this regard the nonlinear relative dynamics of deputy-chief spacecrafts are derived within the concept of the three body problem. The behavior of the two controllers are compared for different tasks of the formation mission in order to determine the more preferred... 

In this paper a fuzzy control strategy of autonomous multiagent systems is presented. The main purpose is to obtain an improvement on the results of designed sliding mode controllers in previous articles using supervisory fuzzy controller. Similarly, a quasi-static swarm model in ndimensional space is introduced wherein the inter-individual interactions are based on artificial potential functions; and the motions of members are in direction with the negative gradient of the combined potentials which are the result of a balance between inter-individual interactions and the simultaneous interactions of the swarm members with their environment. Then a general model for vehicle dynamics of each... 

Fast finite time adaptive sliding mode control of a quadrotor in the presence of uncertainties and unbounded external disturbances is dealt in this paper. To this end, a fractional order sliding surface is first defined and then, an adaptive sliding mode controller is designed to guarantee finite time stability with fast convergence of quadrotor states to the desired trajectory. In this controller, it is assumed that the upper bound of the model uncertainties and external disturbances is a nonlinear function with unknown coefficients. These coefficients are estimated via stable adaptive laws. Finite time stability of the closed-loop system is analyzed using Lyapunov theorem. Simulation... 

In this letter, it is verified that the main result of the above article [1] on converging the voltage tracking error of a buck converter controlled by a fractional-order sliding mode controller cannot be logically justified. The root cause of this inconsistency, which is an improper use of an inequality, is discussed. © 2004-2012 IEEE  

In this study, a 3-DOF dynamic model is developed for the lower limb in the cycling activity using Lagrangian mechanics. An exponential reaching law sliding mode controller is then applied to the system in order to imitate the joints' real motion. The kinematic data of the joints are obtained through conducting experiments with an ergometer bike. Results show acceptable tracking performance for the control system. The study's outcome can be used by rehabilitation experts in their work. It is also useful for the engineers in designing rehabilitation devices or developing muscular models. © 2022 IEEE  

In this paper, we propose a controller based on active sliding mode theory to synchronize chaotic fractional-order systems in master-slave structure. Master and slave systems may be identical or different. Based on stability theorems in the fractional calculus, analysis of stability is performed for the proposed method. Finally, three numerical simulations (synchronizing fractional-order Lü-Lü systems, synchronizing fractional order Chen-Chen systems and synchronizing fractional-order Lü-Chen systems) are presented to show the effectiveness of the proposed controller. The simulations are implemented using two different numerical methods to solve the fractional differential equations. © 2007... 

In this paper, sliding-mode control (SMC) is applied to a z-source converter to control output dc voltage of impedance network. The converter is assumed working in continuous conduction mode (CCM). First a comprehensive review of the literature for z-source inverter (ZSI) and use of sliding mode control in switched converters are performed. The procedure of SMC design used in ZSI is presented. The simulations for the application of SMC in z-source inverter are made and the results are illustrated. The results verify the effectiveness and robustness of the controller. © 2008 IEEE  

The taping mode Atomic Force Microscopic (T-AFM) can be assumed as a cantilever beam which its base is excited by a sinusoidal force and nonlinear potential interaction with sample. Thus the cantilever may cause chaotic behavior which decreases the performance of the sample topography. In order to modeling, using the galerkin method, the PDE equation is reduced to a single ODE equation which properly describing the continuous beam. In this paper a nonlinear delayed feedback control.is proposed to control.chaos in T-AFM system. Assuming model parameters uncertainties, the first order Unstable Periodic Orbits (UPOs) of the system is stabilized using the sliding nonlinear delayed feedback... 

It is aimed to obtain global finite time stabilization of a class of uncertain multi-input-multi-output (MIMO) nonlinear systems in the presence of bounded disturbances by applying nonsingular terminal sliding mode controllers. The considered nonlinear systems consist of double integrator subsystems which interact with each other. In the proposed methods, new terminal sliding surfaces are introduced along with design of proper control inputs. The terminal sliding surfaces are defined such that the global finite time stability of sliding mode dynamic is attained. The control inputs are designed to steer the states into sliding motion within finite time and retain them on the terminal sliding... 

In this paper, an indirect adaptive fuzzy sliding mode controller for a 3-dimensional inverted pendulum as a fully actuated MIMO system is developed. This inverted pendulum, has four degrees of freedom and equations of the system are nonlinear and non-minimum phase. Thus, control of this system is a challenging issue. Accordingly, in this work, general basis of sliding mode control method with reaching rules is expressed for this system, then the fuzzy control theory is combined, and modeling uncertainties of the system are estimated by universal fuzzy approximation theory. Controller parameters are updated by a defined adaptation law to decrease the tracking error of the inverted pendulum.... 

A dynamic model of a remotely operated vehicle (ROV) is developed. The hydrodynamic damping coefficients are estimated using a semi-predictive approach and computational fluid dynamic software ANSYS-CFX™ and WAMIT™. A sliding-mode controller (SMC) is then designed for the ROV model. The controller is subsequently robustified against modeling uncertainties, disturbances, and measurement errors. It is shown that when the system is subjected to bounded uncertainties, the SMC will preserve stability and tracking response. The paper ends with simulation results for a variety of conditions such as disturbances and parametric uncertainties. © 2018, Harbin Engineering University and Springer-Verlag... 

This paper addresses a simple chattering-free and finite-time convergent robust synchronization scheme for a general class of disturbed master and slave chaotic systems. Unlike traditional variable structure control schemes, the proposed controller does not directly include a switching function, and chattering is avoided. The term including switching function is the input of a low-pass filter where the filtered output is used in the controller. Also, numerical differentiation of master and slave state trajectories is not required to implement the controller. Stability of the proposed controller is established using a Lyapunov stability analysis and the finite-time convergence theories.... 

A dynamic model of a remotely operated vehicle (ROV) is developed. The hydrodynamic damping coefficients are estimated using a semi-predictive approach and computational fluid dynamic software ANSYS-CFX™ and WAMIT™. A sliding-mode controller (SMC) is then designed for the ROV model. The controller is subsequently robustified against modeling uncertainties, disturbances, and measurement errors. It is shown that when the system is subjected to bounded uncertainties, the SMC will preserve stability and tracking response. The paper ends with simulation results for a variety of conditions such as disturbances and parametric uncertainties. © 2018, Harbin Engineering University and Springer-Verlag...