Classical Sliding Mode Control Research Articles

Direct Torque Control of an Induction Motor Using Fractional-Order Sliding Mode Control Technique for Quick Response and Reduced Torque Ripple

The performance of electric drive propulsion systems is often degraded by the high torque and flux ripples of an electric drive. Traditional control methods, such as proportional plus integral (PI) controllers and classical sliding mode controllers (SMCs), have shown good response and reduced torque ripple, but even lower ripple content at low voltage levels is required for its effective use in electric vehicle (EV) applications. In this paper, a new direct torque control (DTC) technique with space vector pulse width modulation (SVPWM) using fractional-order sliding mode control (FOSMC) for a two-level inverter (2LI) at constant switching frequency is proposed. The effectiveness of this proposed controller is compared with a conventional proportional-integral controller and a conventional sliding mode controller (SMC). Simulink models are developed using MATLAB version R2018a to analyze the robustness of the proposed control strategy. Simulation results demonstrate the advantage of the proposed controller in reducing the torque ripples at steady state with less settling time during sudden load change conditions. The proposed control technique also demonstrates better utilization of the stator flux through flux trajectory waveforms.

Chattering suppression and hydrodynamic disturbance estimation of underwater manipulators using adaptive fuzzy sliding mode control

Robotic manipulators are nowadays widely used in various underwater scenarios, but their motion control remains a challenging task due to hydrodynamic effects. This article proposes a novel adaptive fuzzy sliding mode control (AFSMC) strategy for precise and robust control of underwater manipulators. To simulate the movement of the robotic manipulators in the underwater environment, the Unified Robot Description Format (URDF) file of a custom-designed electric underwater manipulator is imported into the Simscape Multibody and the hydrodynamic disturbance is modeled according to Morison’s equation. Furthermore, the proposed control strategy takes advantage of the universal approximation capability of fuzzy systems to avoid chattering and observe disturbances by adjusting the control gains of classical sliding mode control (CSMC). And adaptive laws are designed to update the parameters of the fuzzy systems. The strong friction caused by the seal is also compensated by actual test data. In the simulation experiments, a special environment of water flow and variable loads is considered. The results demonstrate that the AFSMC strategy can achieve high precision and strong robustness against disturbances for trajectory tracking. More importantly, the chattering caused by CSMC can be eliminated and the hydrodynamic disturbance can be estimated with high precision through the proposed control strategy.

Application of third-order sliding mode controller to improve the maximum power point for the photovoltaic system

In this research work, a third-order sliding mode control (TOSMC) is suggested to achieve the maximum power point (MPP) in a photovoltaic (PV) system application under variable weather conditions. Due to chattering phenomena, power losses increase when using the classical sliding mode control, and to reduce the steady-state error, ensure a good dynamic response, and achieve high power efficiency, a TOSMC strategy is applied to control the photovoltaic system. The studied system contains the PV panel, the DC–DC boost converter, the resistive load, and the proposed MPP tracking (MPPT) technique based on a TOSMC algorithm. This designed system is simulated using Matlab software, and the obtained simulation results show smaller steady-state error and good overall efficiency.

Tilting Control of Rotor Suspended by Complex Magnetic Bearings with Coupling Torques

For a novel Vernier-gimballing magnetically suspended flywheel (Vernier-gimballing MSFW) with conical magnetic bearing (MB) and Lorentz MB, the rotor’s dynamic model is constructed based on the characteristics of both coupling torque generated by conical MB and nonlinear titling torques generated by Lorentz MB. To make the high-speeding rotor tilt precisely and fast to output large moment, the Vernier-gimballing control method based on the extended state observer (ESO) combined with feedback linearization is presented originally considering torques’ complex nonlinearities, and the sliding mode control (SMC) with ESO is designed to improve the robustness of the closed-loop system. Simulations and experimental tests to verify the rightness and validity of SMC with ESO have been done and all research results indicate that the rotor can track the tilting signal faster and more accurately than classic SMC to output high precision moment.

Robust adaptive sliding mode control for path tracking of unmanned agricultural vehicles

In this paper, a novel adaptive sliding mode control (ASMC) for path tracking of unmanned agricultural vehicles is proposed. It is shown that the designed ASMC is capable of driving the closed-loop lateral position error dynamics to converge to zero asymptotically, where the sliding mode observer (SMO) is designed to estimate the system state so as to adaptively adjust the uncertain bounds of cornering stiffness. Compared with the classical sliding mode control technique, the proposed ASMC not only guarantees strong robustness with respect to parameter uncertainties, disturbance and varying road conditions, but also requires no prior knowledge of the road information. Simulation and experimental results from a typical agricultural wheeled vehicle are provided to verify the excellent performance of the proposed scheme.

Adaptive optimized fractional order control of doubly‐fed induction generator (DFIG) based wind turbine using disturbance observer

AbstractWind energy systems are pollution free and clean form of the renewable energy production. The dynamic model of a wind turbine system based on a doubly fed induction generator (DFIG) is exposed to external disturbances, uncertainties, and nonlinear dynamics. In this paper to ensure the system robustness against external disturbance and uncertainty in system parameters, a novel optimized fractional order robust adaptive sliding mode controller is proposed by utilizing a disturbance observer. The controller's main goal is to track the maximum power point of the wind turbine. In order to show the superiority of the proposed method, the results under normal conditions and in the presence of disturbance and uncertainty have been compared with the classical sliding mode control (SMC) and adaptive sliding mode control (ASMC). The parameters of all three controllers have been optimized by ant colony optimization (ACO) algorithm. The proposed method does not need the knowledge of the upper bounds of model uncertainty and disturbance. Also by using the fractional order operators in the control signal of the proposed method, its robustness against model uncertainty and disturbance is increased and it can extract the maximum power than the other compared methods.

A Robust Voltage Control of DAB Converter With Super-Twisting Sliding Mode Approach

This article presents a supertwisting sliding mode control (ST-SMC) for the isolated dc-dc bi-directional dual active bridge (DAB) power converter for enhanced output voltage regulation. The sliding mode control (SMC) is well-known for its robustness and improved dynamic performance for a nonlinear system. However, it includes the drawback of chattering and degradation of tracking performance. Here, the suggested ST-SMC scheme incorporates the advantages of a sliding mode controller and subsequently eliminates the problem of chattering. The average model of DAB under single phase-shift modulation is considered for controller design, which simplifies the design process. Thus, improved dc-link voltage stability and high robustness for accurate reference voltage tracking are obtained. Further, the proposed scheme provides a robust control for parameter uncertainties as well as the steady-state output voltage contains less ripple when compared to the classical SMC and proportional-integral controller. The experimental results for a 2 kW DAB converter are provided to validate the effectiveness and the robustness of the proposed strategy.

A survey on High-Order Sliding-Mode control design using Lyapunov functions

A survey of (some) recent Lyapunov-based methods to analyze and design High-Order Sliding-Mode (HOSM) controllers and observers is presented. This overview includes also some novel algorithms, taking advantage of a discontinuous integral action, to attain a High-Order Sliding-Mode using a continuous control signal. This account starts presenting the design based on Lyapunov functions of classical sliding-mode controllers using a discontinuous state feedback control law to impose a high-order sliding-mode of arbitrary order. In order to estimate in finite-time the required derivatives of the measured signals for the implementation of the controllers, a Lyapunov-based design of the well-known robust and exact differentiator is shown. As a mechanism to reduce the effect of the undesirable chattering effect a recent method for higher-order sliding-mode controllers has been developed, using a continuous state feedback in conjunction with a discontinuous integral action to enforce a sliding-mode by means of a continuous control signal. The analysis and design tool for this integral controller is also an explicit, strict and particularly tailored Lyapunov function. In order to make this recount accessible to a wide audience the presentation is restricted to the main results, without giving proofs or design details, and leaving aside the rigorous mathematical machinery. For this the main references are provided.

Validation of a Classical Sliding Mode Control Applied to a Physical Robotic Arm with Six Degrees of Freedom

The control of robotic manipulators has become increasingly difficult over recent years due to their high accuracy, performance, speed, and reliability in a variety of applications, such as industry, medicine, research, etc. These serial manipulator systems are extremely complex because their dynamic models include perturbations, parametric variations, coupled nonlinear dynamics, and non-modular dynamics, all of which require robust control for trajectory tracking. This paper compares two control techniques: computational torque control (CTC) and sliding mode control (SMC). In this study, the latter was used for a physical robotic arm with six degrees of freedom (DOF) and online experiments were conducted, which have received little attention in the literature. As a result, the contribution of this work was based on the real-time application of this controller via a self-developing interface. The great resilience of sliding mode controllers to disturbances was also demonstrated in this study.

Robust finite-time adaptive control for high performance voice coil motor-actuated fast steering mirror.

Fast steering mirror (FSM) is an efficient and reliable mechanical device in aerial optical image systems for controlling the beam direction with high precision. With the advantages of compact size, high speed, simple structure, and long linear stroke, voice coil motors are ideal actuators for FSM systems. However, model uncertainty can lead to poor performance or even system divergence, especially in environments with temperature variations, electromagnetic environment changes, etc. This paper proposes a novel finite-time adaptive control (FAC) algorithm for an FSM system to obtain high performance, i.e., positioning accuracy, dynamic performance, and robustness. In addition, the finite-time convergence of the controller is analyzed. In the experiments, the controller is implemented in a DSP-based microprocessor. The step response results show that the proposed algorithm has a shorter setting time, smaller overshoot, and smaller steady-state error compared to classical sliding mode control (SMC). The sinusoidal signal tracking accuracy of FAC + SMC has been improved by 19.8%. In addition, as the model uncertainty increases 10%, the root mean square errors (RMSEs) are 1.73″ and 1.18″ for SMC and FAC + SMC, respectively. With 20% model uncertainty, the RMSEs increase to 2.56″ and 1.85″, respectively. Extensive experiments demonstrate the general effectiveness of the proposed algorithm.

Third‐order super‐twisting control of a double stator asynchronous generator integrated in a wind turbine system under single‐phase open fault

SummaryThis paper deals with the control approach enhancement of a wind power generation system (WPGS) based on a double stator asynchronous generator (DSAG) under single‐phase open fault (SPOF). This type of machine, which collects the qualities of the squirrel cage asynchronous machine and these of the multiphase machine, has attracted the attention of several researchers, especially in the field of the wind energy. Classical sliding mode control (SMC) has been widely developed for the design of control systems. However, the use of SMC has several inconveniences such as the high chattering effect, large transient state error, and less robustness, which limit its utilization in practical applications. In order to improve the performance of the DSAG‐based WPGS, a third‐order super‐twisting controller (TOSTC) with chattering‐free is proposed. Then, an SPOF test is performed to prove the ability of the DSAG to work under degraded circumstances and guarantees to provide appropriate electrical energy to the grid without notable effects. The proposed system and its control under such conditions are illustrated by numerical simulations. The obtained results demonstrate the superior performance of the proposed system.

Twisting Sliding Mode Control based Maximum Power Point Tracking

For a world where energy demand is increasing day by day, available resources are constantly decreasing. At this point, it is very important to be able to benefit from the sun, which is the main energy source, with minimum damage to the environment. It is possible to produce electricity directly from sunlight through PV panels. Due to the limited efficiency of these panels, MPPT algorithms are always required. In this study, Sliding Mode Control (SMC) based Twisting Sliding Mode Control (T-SMC) MPPT, known for its robust structure, was performed and the results were compared with the classical SMC. The proposed MPPT algorithm is simulated with MATLAB/Simulink. The efficiency of T-SMC based MPPT is obtained as nearly 99%.

Adaptive Sliding Mode Control of a Perturbed Satellite in a Formation Antenna Array

Control of a perturbed satellite formation antenna array, with dual quaternion dynamics, is considered. The perturbations and their derivatives are assumed bounded with unknown bounds. The objective of this article is to employ continuous control algorithms which feature adaptive gain nonoverestimation. In this work, three novel dual quaternion-based adaptive continuous sliding mode control algorithms to control a perturbed satellite antenna array are assessed. These methods of adaptive sliding mode control are caspable of handling coupled perturbed systems, such as dual quaternion models. The efficacy of the proposed algorithms is verified via simulations and comparison to the available traditional PD Plus controller and classical sliding mode control methods.

Practical Tracking of Permanent Magnet Linear Motor Via Logarithmic Sliding Mode Control

This article focuses on the fast position tracking problem for the permanent magnet linear motor (PMLM) system under a chattering-reduced sliding mode control signal. To this end, a class of globally nonsingular sliding mode control (SMC) laws, called logarithmic sliding mode (LnSM) control, is proposed in this article. Using the natural logarithm function, a high gain is established at the equilibrium of the sliding mode reduced-order system, which leads to a higher tracking precision and a faster local convergence rate than those of some classical SMCs. In addition, a super-twisting algorithm-based LnSM (ST-LnSM) control is constructed to reduce the chattering typical for first-order SMC, while stabilizing the position tracking system rapidly. Since only a few parameters need to be adjusted, and the employed natural logarithm function is conventionally integrated into most PMLM drivers, the proposed control law is easy to implement in PMLM systems or other industrial servo systems.

Design of Integral Sliding Mode Control for Seismic Effect Regulation on Buildings with Unmatched Disturbance

In this work the robustness properties of Integral Sliding Mode Controller (ISMC) are studied for the problem structural vibration. Selecting the sliding manifold which takes into account the attenuation of the unmatched perturbation is studied as well. This study has two scenarios the first is comparing two types of sliding mode controllers which designed to control 3-story scaled structure supported by Magneto Rheological Damper (MRD). ISMC is compared to classical Sliding Mode Control (SMC) performance, the two controllers checked under effect of Mexico city earthquake. The second scenario compares the proposed controller with other controllers from literature under effect of time scaled El Centro 1940 earthquake. The results show that ISMC performance is better than SMC in scenario one and better than other controllers in scenario two. All the simulation results are obtained by MATLAB.

Dynamic modeling and fuzzy adaptive control strategy for space flexible robotic arm considering joint flexibility based on improved sliding mode controller

Space flexible robotic arms can be installed on space stations or spacecraft to perform on-orbit tasks such as capturing artificial satellites, removing space debris, and assisting astronauts in overhauling. The space flexible robotic arm is a nonlinear complex dynamic system with disturbance torque and nonlinear factors coupled with joint and load flexibility. Many nonlinear terms and disturbance torque in the dynamic equations constitute the uncertain part of the space flexible robotic arm. The space flexible robotic arm is affected by the uncertain part, which will cause trajectory tracking errors. In this paper, the improved sliding mode control strategy based on fuzzy compensation is proposed to compensate for the uncertain part to enhance the trajectory tracking accuracy. Firstly, the dynamics model of the space flexible robotic arm considering joint flexibility is established. Next, the control law of the control strategy is designed by the tanh function. Then, the adaptive law of fuzzy systems is designed by the Lyapunov stability theorem. Finally, numerical simulation analysis and prototype control experiments show that the control strategy can effectively reduce the speed fluctuation of the space flexible robotic arm. Compared with the classical sliding mode control strategy, the control strategy decreased the means of absolute error by 9.1425%, which reveals that the strategy can enhance the trajectory tracking accuracy of the space flexible robotic arm.

FUZZY SLIDING MODE CONTROLLER FOR SEIR MODEL OF EPIDEMIC DISEASE

This paper proposes a vaccination approach based on robust control for the SEIR (susceptible plus exposed plus infectious plus recovered populations) model of epidemic diseases. First, a classic sliding mode controller is investigated based on the SEIR model. Next, fuzzy logic is utilized to better approximate the uncertainties in the SEIR system using the sliding mode controller. Therefore, the proposed controller is a fuzzy sliding mode controller, which, compared to the sliding mode controller, provides an appropriate estimation of systems' actual parameters and removes the chattering phenomenon from the control signal. The stability of the controlled system is guaranteed using the Lyapunov theory simulations in which the classical sliding mode and the proposed controllers are compared, Using data from previous articles. Simulation results show that the proposed controller eliminates the susceptible subpopulation, incubated disease, and infectious diseases, eradicating the disease. Comparison with other methods reveals the better efficiency of the proposed method.

A tracking control design for linear motor using robust sliding mode learning control

<div id="i4c-draggable-container" style="position: fixed; z-index: 1499; width: 0px; height: 0px;"><div class="resolved" style="all: initial;" data-reactroot=""> </div></div><p>In this paper, a tracking robust sliding mode learning control (SMLC) is proposed for a linear motor (LM) system. The proposed controller approach, SMLC, can guarantee a zero tracking error in the absence and presence of system uncertainties of the LM system. Unlike other classical sliding mode control (CSMC), the proposed control system is designed without any prior knowledge of the system perturbation which would facilitate control design and simplify its practical applications. To this end, a recursive learning technique is used which simultaneously adapted based on the previous information of the closed loop system stability. The system stability and convergence analysis are rigorously proved in the sense of the Lybenouve criteria. Finally, simulations results are presented to demonstrate the validity and effectiveness of the SMLC over the CSMC in terms of tracking performance and chattering alleviation.</p>

Forced sliding mode control for chaotic systems synchronization

Synchronization of chaotic systems is considered to be a common engineering problem. However, the proposed laws of synchronization control do not always provide robustness toward the parametric perturbations. The purpose of this article is to show the use of synergy-cybernetic approach for the construction of robust law for Arneodo chaotic systems synchronization. As the main method of design of robust control, the method of design of control with forced sliding mode of the synergetic control theory is considered. To illustrate the effectiveness of the proposed law, in this article it is compared with the classical sliding mode control and adaptive backstepping. The distinctive features of suggested robust control law are the more good compensation of parametric perturbations (better performance indexes—the root-mean-square error (RMSE), average absolute value (AVG) of error) without designing perturbation observers, the ability to exclude the chattering effect, less energy consuming and a simpler analysis of the stability of a closed-loop system. The study of the proposed control law and the change of its parameters and the place of parametric perturbation’s application is carried out. It is possible to significantly reduce the synchronization error and RMSE, as well as AVG of error by reducing some parameters, but that leads to an increase in control signal amplitude. The place of application of parametric disturbances (slave or master system) has no effect on the RMSE and AVG of error. Offered approach will allow a new consideration for the design of robust control laws for chaotic systems, taking into account the ideas of directed self-organization and robust control. It can be used for synchronization other chaotic systems.

Modified grey wolf optimised adaptive super-twisting sliding mode control of rotary inverted pendulum system

This paper proposes a modified grey wolf optimiser-based adaptive super-twisting sliding mode control algorithm for the trajectory tracking and balancing of the rotary inverted pendulum system. The super-twisting sliding mode algorithm severely alleviates the chattering present in the classical sliding mode control. It provides robustness against model uncertainties and external disturbances with the knowledge of the upper bounds of the uncertainties and disturbances. The gains of the super-twisting sliding mode algorithm are selected through adaptive law. Parameters of the adaption law are tuned using a modified grey wolf optimisation algorithm, a meta-heuristic optimisation technique. Lyapunov stability analysis is carried out to analyse the overall control system stability. The performance of the proposed control algorithm is compared with two other sliding mode control strategies present in the literature, therein showing better performance of the proposed control scheme.