Continuous Sliding Mode Control Research Articles

Output Feedback Based Adaptive Continuous Sliding Mode Control for Mechanical Systems With Actuator Faults

Output Feedback Based Adaptive Continuous Sliding Mode Control for Mechanical Systems With Actuator Faults

Continuous Sliding-Mode Control for a Class of Underactuated Systems Subject to Disturbances and Uncertainties

Continuous Sliding-Mode Control for a Class of Underactuated Systems Subject to Disturbances and Uncertainties

A novel generalized sliding mode controller for uncertain robot manipulators based on motion constraints

Abstract. To improve the trajectory tracking performance and robustness for uncertain robot manipulators, a generalized sliding mode controller (GSMC) including an ideal controller and a continuous sliding mode controller (SMC) is proposed from the standpoint of motion constraints. First, the trajectory tracking requirements are formulated as the motion constraints, based on which an ideal controller is proposed to satisfy the motion constraints for robot manipulators whose dynamics are precisely known. Second, an additional continuous SMC is presented to compensate for the effects of uncertainty, and the chattering phenomenon that commonly exists in the SMC can be avoided by the introduction of a smoothing function. Third, Lyapunov analysis is conducted to verify that the proposed GSMC enables the tracking error restricted to a small region around zero. Finally, the numerical simulation and experiment are performed to verify the effectiveness and superiority of the proposed GSMC.

Continuous and Periodic Event-Triggered Sliding-Mode Control for Path Following of Underactuated Surface Vehicles.

This article develops continuous and periodic event-triggered sliding-mode control (SMC) algorithms for path following of underactuated surface vehicles (USVs). Based on the SMC technology, a continuous path-following control law is designed. The upper bounds of quasi-sliding modes for path following of USVs are established for the first time. Subsequently, both continuous and periodic event-triggered mechanisms are considered and added into the proposed continuous SMC scheme. It is demonstrated that with appropriate selecting of control parameters, the use of hyperbolic tangent functions does not affect the boundary layer of quasi-sliding mode caused by event-triggered mechanisms. The proposed continuous and periodic event-triggered SMC strategies can make the sliding variables reach the quasi-sliding modes and stay in there. Moreover, energy consumption can be reduced. Stability analysis shows that the USV can follow a reference path by using the designed method. The simulation results show the effectiveness of the proposed control methods.

Optimal adaptive Lipschitz continuous sliding mode controller with APSO algorithm for an autonomous vehicle

Optimal adaptive Lipschitz continuous sliding mode controller with APSO algorithm for an autonomous vehicle

Optimal adaptive Lipschitz continuous sliding mode controller with APSO algorithm for an autonomous vehicle

Optimal adaptive Lipschitz continuous sliding mode controller with APSO algorithm for an autonomous vehicle

Implementation of Continuous HOSM Controllers in Reaction Wheel Pendulum

This paper presents a performance analysis for the reaction wheel pendulum (RWP) using continuous sliding mode controllers in the proportional integral derivative (PID-like) form. The fourth-order linearized model of the RWP is used for control design to obtain the simulations and the experimental results to verify the theoretical properties of this type of algorithm.

Sliding mode control design using generalized relative degree approach: Aerospace application

Relative degree (RD) approach is a powerful tool for obtaining system's input-output dynamics used for output tracking controller designs of minimum phase systems. Designs using the RD alone can fail due both to insufficient control authority in minimum phase systems, and instability of internal/zero dynamics attributed to nonminimum phase systems. A novel definition and a concept of Practical Generalized RD (PGRD) are proposed in this paper and are used in concert with Sliding Mode Control (SMC) to compensate for system perturbations in minimum phase systems. The use of known Generalized Relative Degree (GRD) in nonminimum phase systems allows for the elimination of internal dynamics. However, instability that emerges in the corresponding control dynamic extension is defeating any output tracking controller design. A novel methodology of using GRD for designing continuous SMC in nonminimum phase systems is presented. An algorithm for generating a bounded solution of the unstable dynamic extension is proposed and used in concert with SMC, allowing robust control design for nonminimum phase systems. The efficacy of the proposed GRD-based approaches is demonstrated on a minimum and nonminimum phase rocket attitude control problem both analytically and via simulation.

Robust sliding mode control for a class of nonlinear systems through dual-layer sliding mode scheme

This article investigates the topic of robust sliding mode control for a class of nonlinear systems in the presence of actuator faults and disturbances. By virtue of a novel integral sliding function combined with an auxiliary controller ‘ν(t)’, a dual-layer sliding mode control framework is established. For system responses, the first layer is an integral sliding mode generated by the actuator output, the second layer is a nonlinear sliding mode generated by ‘ν(t)’. Under the proposal, the nonlinear sliding mode is nested in the integral sliding mode. Compared with the state-of-the-art integral sliding mode control (ISMC) results, not only the inherent robustness is retained, but also the time derivative of integral sliding function can be resisted by ‘ν(t)’. Accordingly, the designed integral sliding mode controller provides more enhancive robustness. With the nested nonlinear sliding mode generated, the matched time derivative of integral sliding function in integral sliding motion dynamics is decoupled from the mismatched disturbances. This decoupling contributes to design a sliding mode controller for ensuring that the system states are uniformly bounded with time-varying performance boundaries. Further, by employing a class of vector-value functions, a novel continuous sliding mode controller is presented such that the sliding modes of the considered systems cannot be lost regardless of actuator faults and disturbances. At last, an illustrative example verifies the effectiveness of the theoretical findings.

Continuous sliding mode control for uncertain linear time-invariant systems with matched and unmatched uncertainties using the Lyapunov-function integral sliding mode

In this paper, a novel integral sliding mode (ISM) design was used to deal with the problem of unmatched uncertainty rejection in uncertain linear time-invariant (ULTI) systems. First, a new type of Lyapunov-function integral sliding mode (LFISM) with the ability to suppress unmatched uncertainty and disturbance was introduced. Despite the unmatched uncertainty, the system is robustly stable in ideal sliding mode or ultimate uniform bounded (UUB) stable in non-ideal sliding mode on the proposed LFISM surface. Then, the corresponding sliding mode control (SMC) control was designed based on the augmented system with the added integrator to ensure the reachability of the proposed LFISM, which led to a continuous sliding mode control (CSMC). The proposed method was applied to an academic case and an aircraft attitude control plant, and the comparison simulation results showed that the LFISM has better performance and rejection ability to the unmatched uncertainties.

Robust Adaptive Control Strategy for a Bidirectional DC-DC Converter Based on Extremum Seeking and Sliding Mode Control

This paper presents a new control strategy that combines classical control and an optimization scheme to regulate the output voltage of the bidirectional converter under the presence of matched and mismatched disturbances. In detail, a control-oriented modeling method is presented first to capture the system dynamics in a common canonical form, allowing different disturbances to be considered. To estimate and compensate for unknown disturbances, an extended state observer (ESO)-based continuous sliding mode control is then proposed, which can guarantee high tracking precision, fast disturbance rejection, and chattering reduction. Next, an extremum seeking (ES)-based adaptive scheme is introduced to ensure system robustness as well as optimal control effort under different working scenarios. Finally, comparative simulations with classical proportional-integral-derivative (PID) control and constant switching gains are conducted to verify the effectiveness of the proposed adaptive control methodology through three case studies of load resistance variations, buck/boost mode switching, and input voltage variation.

Robust bipartite tracking consensus of multi-agent systems via neural network combined with extended high-gain observer

In this paper, the robust bipartite tracking consensus problem for second-order multi-agent systems has been addressed in the presence of lumped disturbances and unknown velocity information. The leader’s dynamics are modeled by uncertain fractional-order equality based on the neural network (NN), and the followers can only obtain the position information of the leader under the signed networks. A novel robust bipartite tracking consensus control scheme is developed by combining the NN approximators, the continuous sliding mode control (SMC) strategy, and the improved extended high-gain observer (EHGO). The improved EHGO is used to compensate for and estimate each agent’s lumped disturbances and unknown velocity information in the controller design process. Moreover, NN is constructed to approximate the velocity and acceleration of the uncertain leader’s dynamics for generating the feedforward signal of controllers, and the adaptive update laws of estimation parameters are generated online based on the Lyapunov function. Finally, the effectiveness of the proposed control strategy is verified by some numerical simulations.

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.

Continuous output feedback sliding mode control for underactuated flexible-joint robot

The tracking control based on output feedback for a category of flexible-joint robot (FJR) systems is investigated in this brief. Control performance of the systems is inevitably bearing the brunt of various unknown time-varying disturbances, which can be categorized to be matched and mismatched and generally cover internal parameter uncertainties, couplings, unmodelled dynamics, and external load or changing operating environments. To cope with these disturbances, the mismatched disturbances are first transferred to the matched ones by a flatness method, which eliminates the computational cost of estimating mismatched disturbances. Then, a generalized proportional integral observer (GPIO) is constructed to estimate the unavailable states and disturbances. By integrating the estimated disturbance and states provided by the GPIO, a novel dynamic sliding surface is constructed. Finally, a continuous sliding mode control (CSMC)-based output feedback control framework is further designed. The presented control strategy only requires link position information and is continuous, which can effectively reduce the chattering driven by the high-frequency switching item in the traditional SMC method. Asymptotic convergence of output tracking error is guaranteed by theoretical analysis under some mild conditions. Comparative tests on a two-link FJR verify the claimed control performance.

An arbitrary-order continuous sliding mode control technique for nonlinear PWR-type nuclear power plants

This paper presents an arbitrary order continuous-time sliding mode controller based on the super-twisting algorithm for a nonlinear pressurized water nuclear power plant. A proportional-derivative terminal sliding surface is designed to achieve the finite time convergence and to enhanced the tracking performance. The proposed controller is chattering free, which is always preferable in most of the practical applications and, it is robust against Lipschitz in time uncertainties. The implementation of the proposed controller requires only the information about the system output, and thus, it is most suitable for large scale complex systems, such as nuclear power plants. Superiority of the proposed controller over some conventional control techniques in the presence of uncertainties is shown with the help of simulation results in the MATLAB/Simulink environment.

A Lipschitz continuous sliding mode control for implicit systems

In this paper, implicit systems with uncertain input matrix subjected to matched Lipschitz disturbances are considered. For such kind of systems a Lipschitz continuous control, achieving admissible solutions for implicit systems is proposed. The developed methodology consists of two steps. In the first step a stable sliding surface is designed after transforming the original system into a regular like form. Then a first order sliding mode controller through an integrator is designed which will ensure finite-time convergence to the sliding manifold and the exponential convergence to the origin in spite of the presence of Lipschitz disturbances and uncertain input matrix.

Robust Cooperative Optimal Sliding-Mode Control for High-Order Nonlinear Systems: Directed Topologies.

This article is concerned with the robust cooperative optimal control of nonlinear multiagent systems (MASs) with external disturbances and modeling uncertainties. Using the super-twisting algorithm, a continuous sliding-mode control protocol is presented for high-order nonlinear MASs with multiple inputs. The sliding-mode dynamics is modeled by the Takagi-Sugeno fuzzy approach, and the nominal control protocol that guarantees the robust optimization of the cost function is designed. Directed topologies are allowed using the presented protocol, and many assumptions about topologies are removed. Finally, three numerical examples are reported to demonstrate the effectiveness and improved performance of the presented protocol.

Improved control scheme of a dual star induction generator integrated in a wind turbine system in normal and open-phase fault mode

A robust control scheme of a wind turbine system (WTS) based on a dual star induction generator (DSIG) in normal and open-phase fault (OPF) mode is presented in this paper. The strong point of this generator that recently attracted the attention of several researchers especially in wind energy field is that it combines the advantages of the squirrel cage induction machine and those of multiphase ones. This research is carried out to reach two main objectives. Firstly, in order to ensure a robust control of the DSIG-based WTS with a low effect of chattering phenomenon, an improved control scheme based on super-twisting continuous sliding mode controllers (STCSMC) is proposed. The second objective is to verify, by an OPF test, the ability of the DSIG to operate in degraded conditions. Finally, simulated results show that more robust control is achieved and that the DSIG-based WTS continues to provide suitable electrical energy to the grid without remarkable effects.

Adaptive Disturbance-Observer-Based Continuous Sliding Mode Control for Small Autonomous Underwater Vehicles in the Trans-Atlantic Geotraverse Hydrothermal Field with Trajectory Modeling Based on the Path

Considering intense hydrothermal activities and rugged topography in a near-bottom environment of the trans-Atlantic geotraverse (TAG) hydrothermal mound, a small autonomous underwater vehicle (S-AUV) will suffer from time-varying disturbances, model uncertainties, actuator faults, and input saturations. To handle these issues, a fault-tolerant adaptive robust sliding mode control method is presented in this paper. Firstly, unknown disturbances, model uncertainties, and actuator faults of the S-AUV are synthesized into a lumped uncertain vector. Without requiring the upper bound and gradient of the uncertainties, a continuous adaptive finite-time extended state observer is designed to estimate the lumped uncertain vector. Then, an auxiliary dynamic system composed of continuous functions is introduced to deal with input saturations, thereby contributing to achieving fixed-time trajectory tracking control of S-AUVs. Based on a designed continuous fixed-time nonsingular fast sliding mode surface, the proposed continuous adaptive controller is chattering free. Simulated topography is built according to topographic data of the TAG mound, and a smooth trajectory model is constructed by cubic spline interpolation. Comprehensive simulations performed on an actual S-AUV model are given to validate the effectiveness and superiority of the presented algorithm.

Modular modeling and coordination control scheme for an underwater cooperative transportation performed by two I-AUVs

Intervention Autonomous Underwater Vehicles (I-AUVs), also known as Underwater Vehicle Manipulator Systems (UVMSs), are an alternative for reducing costs and increasing safety in underwater operations which require dexterous manipulation. Beyond the well-posed and currently studied manipulation scenarios, the cooperative underwater transportation is a promising and challenging task, still not extensively explored. This paper aims to contribute to this latter problem by addressing the modeling and control system design of a cooperative underwater transportation performed by two planar I-AUVs, each of them composed by an AUV linked to a 2-Degrees of Freedom (DoFs) serial manipulator. A hierarchical approach for deriving the equations of motion through the Modular Modeling Methodology (MMM) is presented. Also, a complete coordination scheme composed of the Inverse Kinematics (IK) and motion control modules is proposed. A new IK control is formulated on the jerk level with the Super-Twisting Algorithm (STA) to prevent numerical drift and uncertainties while considering secondary objectives. The low-level motion control is synthesized within a continuous Sliding Mode Control (SMC) algorithm to compensate for the modeling errors and external disturbances. The coordination scheme is verified through numerical simulation considering a scenario in which an object is transported by the two I-AUVs over a predefined path. The analysis is made more realistic by considering the thrusters and motors dynamics along with sensors measurements, sampling effects and an optimal state estimator. Modeling errors and external disturbances are also considered in the analysis. The results reveal the suitability of the proposed modeling and coordination approaches for numerical simulation and control of the I-AUVs during underwater transportation.