Application Of Sliding Mode Control Research Articles

An Application of Neural Network-based Sliding Mode Control for Multilevel Inverters

Multi-level 3-phase inverters using cascaded H-bridges are becoming prominent in the electric drive and renewable energy sectors due to their high capacity and ability to withstand high voltage shocks. Therefore, the modulation and control techniques used in these multilevel inverters have a crucial influence on the quality of the output voltage they produce. The significantly high common-mode voltage amplitude they generate is one of their disadvantages, causing leakage currents and harmonics. This article proposes a new technique using sliding mode control combined with neural networks to manage a three-phase multi-level inverter. The research objective of this innovative technique is to eliminate the need for current controllers and conventional modulation that relies on carrier signals, reducing hardware calculations and enhancing dynamic response. In addition, it demonstrates the ability to minimize harmonics, common mode voltage, and the number of switching counts, thereby limiting the inverter switching losses and increasing device performance. Simulation results performed on a 5-level 3-phase inverter using cascaded H-bridges have confirmed the effectiveness of the proposed method.

Novel Integral Sliding Mode Control Applied to High-Power DC Power Supplies

Novel Integral Sliding Mode Control Applied to High-Power DC Power Supplies

Application of Disturbance Observer-Based Fast Terminal Sliding Mode Control for Asynchronous Motors in Remote Electrical Conductivity Control of Fertigation Systems

In addressing the control of asynchronous motors in the remote conductivity of fertigation machines, this study proposes a joint control strategy based on the Fast Terminal Sliding Mode Control-Disturbance Observer (FTSMC-DO) system for asynchronous motors. The goal is to enhance the dynamic performance and disturbance resistance of asynchronous motors, particularly under low-speed operating conditions. The approach involves refining the two-degree-of-freedom internal model controller using fractional-order functions to explicitly separate the controller’s robustness and tracking capabilities. To mitigate the motor’s sensitivity to external disturbances during variable speed operations, a load disturbance observer is introduced, employing hyperbolic tangent and Fal functions for real-time monitoring and compensation, seamlessly integrated into the sliding mode controller. To address issues related to low-speed chattering typically associated with sliding mode controllers, this study introduces a revised non-singular fast terminal sliding mode surface. Additionally, guided by fuzzy control principles, the study enables real-time selection of sliding mode approaching law parameters. Experimental results from the asynchronous motor control platform demonstrate that FTSMC-DO control significantly reduces adjustment time and speed fluctuations during operation, minimizing the impact of load disturbances on the system. The system exhibits robust disturbance rejection, improved robustness, and enhanced control capability. Furthermore, field tests validate the effectiveness of the FTSMC-DO system in regulating remote electrical conductivity (EC) levels. The control time is observed to be less than 120 s, overshoot less than 16.1%, and EC regulation within 0.2 mS·cm−1 over a pipeline distance of 120 m. The FTSMC-DO control consistently achieves the desired EC levels with minimal fluctuation and overshoot, outperforming traditional PID and SMC methods. This high level of precision is crucial for ensuring optimal nutrient delivery and efficient water usage in agricultural irrigation systems, highlighting the system’s potential as a valuable tool in modern, sustainable farming practices.

Emulator of electrocardiographically biopotentials based on a sliding mode controlled buck power converter

The primary objective of this research is to present the design of an artificial signal generation system of electrocardiography continuous signals based on the application of a buck power converter. A first-order sliding mode control application for a buck direct current–direct current power converter induces the generation of continuous variations of a direct current voltage as the response of a power converter. The output voltage reproduces the required electrocardiography signals corresponding to the regular or pathological variants. The equivalent control method permits introducing a novel design of a kind of cascade-like sliding mode controller that can regulate both current and voltage operative loops simultaneously, which force the controlled tracking of the reference bioinspired voltages at the output of the buck power converter. For the developed control design, the current regulation is enforced as the primary outcome of the sliding mode controller. Consequently, the required voltage from the buck converter is produced, regulating the switching operation in the electrical power system. The suggested control operates robustly concerning the internal uncertainties and perturbations for both input and voltage signals. Furthermore, the variation of the needed gain for the designed sliding mode controller is developed by studying the online amplitude of the electrocardiography electrophysiological signals used as references and their time derivatives over time. Two reference signals were developed to validate the controllers with the same quality at the numerical simulation and using some experimental validations. The proposed signals used as references were successfully generated in both evaluated cases.

Neural network-based sliding mode controllers applied to robot manipulators: A review

In recent years, numerous attempts have been made to integrate sliding mode control (SMC) and neural networks (NN) in order to leverage the advantages of both methods while mitigating their respective disadvantages. These endeavors have yielded significant achievements, leading to diverse applications in enhancing control performance for nonlinear objects, including robots. This paper primarily focuses on investigating critical technical research issues, potential applications, and future perspectives of SMC based on NNs when applied to robot manipulators. Firstly, a comprehensive examination is conducted to assess the advantages, disadvantages, and potential applications of SMC and its various variants. Secondly, recent advancements in control systems have introduced NNs as a promising innovation. NNs offer an alternative approach to adaptive learning and control, effectively addressing the technical challenges associated with SMCs. Finally, the assessment of these combined approaches' advantages and limitations is based on studies conducted over the last few decades, along with their future development directions.

Sliding mode control and its application in switched systems: A survey

According to the development and research of sliding mode variable structure control (SMVSC) in recent years. This paper mainly reviews the development and applications of some popular sliding mode control (SMC), such as adaptive SMC, discrete-time system SMC, fuzzy SMC, and neural network SMC. With the research and development of switched system (SS), the research scholars can deal with the complex and changeable system more effectively by combining the SMC with the SS, so as to improve the efficiency and stability of the system. The theoretical research and applications of SMC combined with fuzzy SS, predictive SS and uncertainty SS are also becoming more and more attractive. The purpose of this paper is to analyze and organize the current research status of the popular directions of SMC, and provide the readers with the latest research results on the application directions and new trends in the field of SMC. By considering these theoretical studies and numerous applications, the research and development of intelligent control techniques and switching systems based on sliding mode control are reviewed. Finally, some prospects for related research are presented.

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.

Investigation of SVPWM Based Sliding Mode Control Application on Dual-Star Induction Motor and Dual Open-End Winding Induction Motor

The present paper deals with a comparative study of the Sliding Mode Control (SMC) technique application on three-phase Dual Star Induction Motor (DSIM) topology and the Dual Open-End Winding Induction Motor (DOEWIM). Where, in these two topologies the Space Vector Pulse Width Modulation (SVPWM) has been used for the control of the two two-level inverters and the four two-level inverters, which have been used to power the two motors under application respectively. The main objective of this study is to demonstrate the higher performances of the DOEWIM under the application of SMC combined with SVPWWM, which aims to overcome the main drawbacks faced when using the conventional topology DSIM in industrial applications. Especially in terms of decreasing the harmonics content in the stator current, reducing the overall ripples of the developed electromagnetic torque, the elimination of the common mode voltage and increasing the robustness against the load torque variation and speed reverse. The obtained simulation results show clearly the main advantages of using the topology of DOEWIM compared to the DSIM topology which present a very promising application especially in heavy industrial requiring high power motors.

Robust Nonlinear Terminal Integral Sliding Mode Torque Control for Wind Turbines Considering Uncertainties

Power maximization and fatigue alleviation are essential for variable speed wind turbines operating in partial load zone. It is within this framework that the present paper gives a global state of art of the application of sliding mode control (SMC) for wind turbines and proposes a new application of Terminal Integral Sliding Mode Control (TISMC) for variable speed wind turbines, described as a mechatronic system, represented by uncertain lumped mass dynamics. In order to represent a relatively exhaustive study, a stability proof is also synthesized and verified using the Lyapunov criterion. In order to evaluate the proposed solution, a numerical validation has been done on Controls Advanced Research Turbine (CART 2) using the National Renewable Energy Laboratory (NREL) simulator Fatigue, Aerodynamics, Structures and Turbulence (FAST). For more accuracy 9 DOFs (Degrees of Freedom) were enabled with a realistic turbulent wind field. The obtained results shown the effectiveness of TISMC compared to some existing linear and nonlinear controllers in term of output power maximization and loads mitigation.

Design and Stability Analysis of a Robust-Adaptive Sliding Mode Control Applied on a Robot Arm with Flexible Links

Modelling errors and robust stabilization/tracking problems under parameter and model uncertainties complicate the control of the flexible underactuated systems. Chattering-free sliding-mode-based input-output control law realizes robustness against the structured and unstructured uncertainties in the system dynamics and avoids the excitation of unmodeled dynamics. The main purpose of this paper was to propose a robust adaptive solution for stabilizing and tracking direct-drive (DD) flexible robot arms under parameter and model uncertainties, as well as external disturbances. A lightweight robot arm subject to external and internal dynamic effects was taken into consideration. The challenges were compensating actuator dynamics with the inverter switching effects and torque ripples, stabilizing the zero dynamics under parameter/model uncertainties and disturbances while precisely tracking the predefined reference position. The precise control of this kind of system demands an accurate system model and knowledge of all sources that excite unmodeled dynamics. For this purpose, equations of motion for a flexible robot arm were derived and formulated for the large motion via Lagrange’s method. The goals were determined to achieve high-speed, precise position control, and satisfied accuracy by compensating the unwanted torque ripple and friction that degrades performance through an adaptive robust control approach. The actuator dynamics and their effect on the torque output were investigated due to the transmitted torque to the load side. The high-performance goals, precision and robustness issues, and stability concerns were satisfied by using robust-adaptive input-output linearization-based control law combining chattering-free sliding mode control (SMC) while avoiding the excitation of unmodeled dynamics. The following highlights are covered: A 2-DOF flexible robot arm considering actuator dynamics was modelled; the theoretical implication of the chattering-free sliding mode-adaptive linearizing algorithm, which ensures robust stabilization and precise tracking control, was designed based on the full system model including actuator dynamics with computer simulations. Stability analysis of the zero dynamics originated from the Lyapunov theorem was performed. The conceptual design necessity of nonlinear observers for the estimation of immeasurable variables and parameters required for the control algorithms was emphasized.

Quad-rotor adaptive sliding mode control using only position and yaw sensors: Generalized relative degree approach

An output tracking controller design is proposed for perturbed Quad-Rotor Unmanned Aerial Vehicles (QR-UAV) using a generalized relative degree approach that allows employing only four measurements of the QR-UAV states, position (x,y,z) and yaw angle (ψ), instead of the traditional six variables. Adaptive Super-Twisting (ASTW) control is applied for controlling the yaw angle (ψ) in the presence of perturbations with bounded derivatives and unknown bounds. The relative degree approach allows the application of Adaptive Continuous High Order Sliding Mode (ACHOSM) control for controlling the position states (x,y,z), in a single loop, in the presence of smooth perturbations with bounded derivatives and unknown bounds. The proposed single loop ASTW and the ACHOSM controllers, with non-overestimated control gains, drive the position trajectory and yaw tracking errors to zero asymptotically in the absence of dynamics of actuators and sensors. Finite convergent time Filtering HOSM differentiators are used to facilitate the ACHOSM controllers in the presence of the noisy measurements. The proposed single loop sliding mode controllers have been validated via simulations.

Variable Gain Super Twisting Sliding Mode Control (VGSTW) application in longitudinal plane of Autonomous Underwater Glider (AUG)

This paper presents a robust control design using variable gain super twisting sliding mode control application in Autonomous Underwater Glider (AUG). AUGs are known as underactuated systems and very nonlinear in nature make difficult to control. The controller is designed for longitudinal plane of an AUG that tracks the pitching angle and net buoyancy of a ballast pump for nominal system, system in existence of external disturbance and parameter variations in hydrodynamic coefficients. The Lyapunov stability theorem has proved that the proposed control law is satisfied the stability sufficient condition. The simulation results have shown that the proposed controller has improved the transient response, reduced steady error and chattering effects in control input and sliding surface in all cases.

An extensive critique of sliding mode control and adaptive neuro‐fuzzy inference system for nonlinear system

AbstractNonlinear control hypothesis is the region of control hypothesis which manages frameworks that are nonlinear, time‐variant, or both. Nonlinear control structures have extended high prevalence fundamentally because of the wide use of hypothetical intends to deal with credible issues in different zones of engineering and medical aspects. Sliding mode control (SMC) is a nonlinear control strategy applied when the deterministic model of the nonlinear system is discrepant with actual plant in terms of plant parameters and undetermined external disturbances. SMC is a sort of nonlinear control that accentuates zero error convergence modeling error, demonstrating nonlinearities and outside aggravations. Adaptive neuro‐fuzzy inference system (ANFIS) captures neural associations and soft reason guidelines in a single framework. ANFIS causes fewer errors and is more obvious to the customer isolated from the ANN. The paper centers that neural organizations accept a critical capacity in controlling nonlinear frameworks. This review aims an overview of existing methods for nonlinear control and application of SMC for nonlinear system based on ANFIS.

Sliding Mode Control: Overview of Its Applications in Power Converters

In this article, we present an overview of sliding mode control (SMC) and its applications in power converters. Owing to the distinguished features such as fast dynamic response, robustness, order reduction, and implementation simplicity, SMC is widely studied in power converters. First, we briefly review SMC design. Then, we compare the classical current control and SMC methods for a grid-connected inverter application. Next, we summarize the advantages and disadvantages of SMC. Existing SMC applications in various power converters are presented and a block diagram for each converter topology is given. Finally, we discuss future challenges in SMC.

Stabilizing Sliding Mode Control Design and Application for a DC Motor: Speed Control

Stabilizing Sliding Mode Control Design and Application for a DC Motor: Speed Control

Rotor vibration control of hybrid pole bearingless switched reluctance motor with C-dump converter

Rotor vibration control during start up, acceleration and deceleration phases is one of the key problems besides stable levitation, in high-speed applications of bearingless switched reluctance motor (BSRM). In this paper, an effective intelligent sliding mode controller is proposed for suppressing the rotor vibration due to residual unbalance and external disturbance during levitation and motoring phases. The parameters of time-varying sliding surface for avoiding high control gains and chattering are adjusted integrating the sliding mode control (SMC) and features of fuzzy logic control. The experimental studies conducted on a prototype BSRM system confirm that the application of fuzzy SMC guarantees the robust performance with less chattering under model uncertainties and unknown external disturbances compared to classical sliding mode controller.

An Improved Sliding Mode Control via Discrete Time Optimal Control and its Application to Magnetic Suspension System

Sliding Mode Control (SMC) is a robust control strategy that is insensitive to system uncertainties and external disturbances. It is widely used in designing controllers, observers and differentiators. However, the inevitable chattering problem affects the SMC applications in real-life engineering. This paper presents an improved SMC algorithm based on discrete second-order time optimal control (TOC). The proposed algorithm adopts a simple method to calculate the distance from the state variable to the sliding surface, and it can adjust the linear or nonlinear control law according to the calculated distance. On the other hand, the control law deviation in the two-step reachable region is corrected. The improved control algorithm shortens the convergence time and reduces the chattering problem of the system. It is applied to the design of magnetic suspension controllers. This allows the system to achieve a fast, accurate and stable suspension target when the system has external disturbances and internal parameter perturbations.

Stochastic Sliding Mode Control for Parametric Uncertain Systems Using Functional Observer

This brief addresses the problem of sliding mode control (SMC) design using functional observer (FO) for discrete-time stochastic systems with norm-bounded parametric uncertainty in the system matrix. SMC is a most powerful, robust control technique to stabilize discrete-time systems. However, the application of SMC becomes difficult when the system states are not accessible for feedback. Hence the proposed method uses FO-based approach for estimating SMC design. To mitigate the side effect of the parameter uncertainty on the estimation error, a sufficient condition of stability is provided based on Gershgorin disc theorem. The feasibility and effectiveness of our derived results are illustrated through a simulation example.

Trends and Development of Sliding Mode Control Applications for Renewable Energy Systems

Based on the matured theoretical framework of sliding mode control for varied, nonlinear, and unpredictable systems, practical designs of sliding mode control have been developed to suit the purpose of controlling power converters under various operating conditions. These design guidelines are particularly valuable for emerging technologies with renewable energy sources. This paper presents a discussion on the recent development of sliding mode control applications for renewable energy systems, and further examines the current trends of achieving efficiency improvement of renewable energy systems and load protections against large overshoot/undershoot in transient states, by utilizing the fast-dynamic-tracking capability of the sliding mode control. Three comparative case studies between the sliding mode control and proportional-integral control involving, namely, a low-power wind energy conversion system, a series-series-compensated wireless power transfer system, and a multiple energy storage system in a direct current (DC) microgrid, are provided.

Efficient and Novel voltage control method using DC-DC Cuk Converter under Load Variation

A control system is a set of mechanical or electronic devices that regulates other devices or systems by way of control loops. Typically, control systems are computerized. The mode of operation in a Control System where controlling variables is a function of the system and the structure is changed knowingly according to set of rules, which are already declared: for example a sensor based system, is called as sliding control mode where the feedback control system response is limited and revolves around surface in the space to a point of equilibrium. 
 In this mode of schemes, a switching variable dictates which form of control is to be used at a given instant, depending on the position of the state from the surface. First a set of points for which the switching function is null is used called as sliding surface. Sliding Mode Control (SMC) is a very robust technique which can handle sudden and large changes in dynamics of the system which can be applied to many areas like controlling of motor, aircraft and spacecraft, process control and power systems. SMC is one of the best tool in the industry to design controllers for the systems which has variable values, and provides robust properties against matched uncertainties, However,this use of SMC can only be achieved after the occurrence of the sliding mode. Before the occurrence of the switching function as null i.e. during the reaching phase, the system is affected by even matched ones. Several first order SMC applications for linear and nonlinear systems can be found in the literature [1]. Hence to eliminate the reaching phase and to make sure the ruggedness of the system throughout the entire closed-loop system response Integral Sliding Modes are used. In this paper a design procedure for sliding mode controllers for better control of voltage is applied, and then the ideas implemented are extended to all integral sliding modes in order to ensure optimum operation of entire system response[2]. Necessary conditions for the existence of sliding modes are also given. The closed-loop system is also proved to be exponentially stable. Simulation and experimental tests using the prototype of controlled DC-DC CUK converter were performed to validate the proposed control approach.