Dynamic Terminal Sliding Mode Control Research Articles

Adaptive Optimal Terminal Sliding Mode Control for T-S Fuzzy-Based Nonlinear Systems

This study utilizes the Takagi–Sugeno fuzzy model to represent a subset of nonlinear systems and presents an innovative adaptive approach for optimal dynamic terminal sliding mode control (TSMC). The systems under consideration encompass bounded uncertainties in parameters and actuators, as well as susceptibility to external disturbances. Performance evaluation entails the design of an adaptive terminal sliding surface through a two-step process. Initially, a state feedback gain and controller are developed using Linear Matrix Inequality (LMI) techniques, grounded on H2-performance and partial eigenstructure assignment. Dynamic sliding gain is subsequently attained via convex optimization, leveraging the derived state feedback gain and the designed terminal sliding mode (TSM) controller. This approach diverges from conventional methods by incorporating control effort and estimating actuator uncertainty bounds, while also addressing sliding surface and TSM controller design intricacies. The TSM controller is redefined into a strict feedback form, rendering it suitable for addressing output-tracking challenges in nonlinear systems. Comparative simulations validate the effectiveness of the proposed TSM controller, emphasizing its practical applicability.

Adaptive backstepping dynamic sliding mode control for maglev turning motor spindle based on limited time preset performance

In the process of turning a maglev motorized spindle, there are problems such as system model time-varying, cross-coupling of control parameters, difficult measurement of system state variables, and nonlinear characteristics of active magnetic bearings, which lead to the inevitable cutting chatter phenomenon, difficult control algorithm design, and then the reduction of workpiece surface quality and accuracy, affecting machining efficiency and tool life. In this paper, the “multimodal-distributed parameter” model is extended to the “magnetic bearing-rotor-workpiece” variable mass turning process. An adaptive backstepping fast dynamic terminal sliding mode control is designed to address the model’s time-varying parameters and cross-coupling issues. In view of the difficulty in measuring the vibration displacement at the cutting point, the displacement field reconstruction method was introduced to reconstruct the vibration displacement field online and provide effective feedback for the previously designed control strategy. Finally, the proposed controller is applied to adjust and control the turning process of a maglev motorized spindle and compared with other advanced controllers. The simulation results show that the proposed control method has a better control effect than other control methods in the presence of unmodeled dynamics, uncertainties, and external disturbances.

Finite-Time Disturbance Observer of Active Power Filter With Dynamic Terminal Sliding Mode Controller

This article proposes an adaptive dynamic terminal sliding mode control (ADTSMC) based on a finite-time disturbance observer (FTDO) for a single-phase active power filter (APF). Aiming at the internal parameter fluctuations and external unknown disturbances in the APF system, an FTDO is designed to compensate for the unknown uncertainties. Then, the proposed dynamic terminal sliding mode control (DTSMC) method combines the dynamic sliding mode control and the terminal sliding mode control to achieve finite-time convergence and weaken system chattering. In order to ensure the organic combination of FTDO and DTSMC, a dual-hidden-layer recurrent neural network (DHLRNN) is used to estimate the gain of sliding mode switching term adaptively so that FTDO can achieve the maximum disturbance estimation. Hardware experiments verify that the designed ADTSMC method has satisfactory robustness and harmonic compensation property under different nonlinear loads.

Finite-Time Disturbance Observer of Nonlinear Systems

In practical applications, for highly nonlinear systems, how to implement control tasks for dynamic systems with uncertain parameters is still a hot research issue. Aiming at the internal parameter fluctuations and external unknown disturbances in nonlinear system, this paper proposes an adaptive dynamic terminal sliding mode control (ADTSMC) based on a finite-time disturbance observer (FTDO) for nonlinear systems. A finite-time disturbance observer is designed to compensate for the unknown uncertainties and a dynamic terminal sliding mode control (DTSMC) method is developed to achieve finite time convergence and weaken system chattering. Moreover, a dual hidden layer recurrent neural network (DHLRNN) estimator is proposed to approximate the sliding mode gain, so that the switching item gain is not overestimated and optimal value is obtained. Finally, simulation experiments of an active power filter model verify the designed ADTSMC method has better steady-state and dynamic-steady compensation effects with at least 1% THD reduction in the presence of nonlinear load and disturbances compared with the simple adaptive DTSMC law.

Experimental validation of adaptive RBFNN global fast dynamic terminal sliding mode control for twin rotor MIMO system against wind effects

In this paper, an Adaptive RBFNN global fast dynamic terminal sliding mode control (ARBFNNGFDTSMC) is designed to situate the main and tail angles of a twin rotor MIMO system (TRMS). The control objective is to stabilize the TRMS in a reference position or follow a predefined trajectory. An adaptive RBFNN has been used in order to identified unknown nonlinear dynamics of the TRMS. In addition, another adaptive control expressions has been added to diminish the wind gusts, external disturbance effects, and to compensate the estimation errors of the adaptive RBFNN. Moreover, the stability analysis in closed-loop is assured by using Lyapunov method. The developed controller is applied to the TRMS with cross coupling between tail and main subsystems without decoupling procedure. Experimental results prove the good control tracking performance in presence of wind gusts and external disturbances.

Finite-Time Fast Dynamic Terminal Sliding Mode Maximum Power Point Tracking Control Paradigm for Permanent Magnet Synchronous Generator-Based Wind Energy Conversion System

Due to the intermittent nature of wind, there exists a major disparity between the power generation from the wind and the demand of electricity. Hence, a sophisticated maximum power point tracking (MPPT) control paradigm must be formulated for maximizing the power extraction from the wind. This research article focuses on the formulation of a nonlinear fast dynamic terminal sliding mode control (FDTSMC)-based MPPT strategy for optimizing the power extraction from a 3kW, variable speed, fixed-pitch wind energy conversion system equipped with a permanent magnet synchronous generator. The proposed MPPT strategy is compared with the benchmark fast terminal sliding mode control, conventional sliding mode control, feedback linearization control and proportional integral derivative control-based MPPT strategies under a stochastic wind speed profile. The proposed paradigm has been found superior in its tracking performance by converging the output tracking error to zero in a finite time, realizing a high precision performance, offering fast dynamic response, reducing the chattering to a minute level and guaranteeing global robustness. The superior performance and effectiveness of the proposed FDTSMC-based MPPT control paradigm is tested and validated through extensive MATLAB/Simulink simulations.

Designing dynamic fractional terminal sliding mode controller for a class of nonlinear system with uncertainties

In this paper, a novel terminal sliding manifold is introduced. Then, based on new sliding surface, we proposed two new fast converging robust controllers. The first controller is a fractional terminal sliding mode controller for a class of fractional order chaotic system in order to decrease singularity problem as well increasing fast convergence. Stability analysis of the system has been proved by Lyapunov stability theorem. The second one is the fractional dynamic terminal sliding mode controller for a class of fractional second order chaotic system so as to reduce chattering problem. For each, numerical simulations have been done to show the applicability and effectiveness of the proposals.

Observer-based Composite Adaptive Dynamic Terminal Sliding-mode Controller for Nonlinear Uncertain SISO Systems

In the present paper, the observer-based composite adaptive terminal sliding-mode control is investigated for the nonlinear uncertain system. First, an adaptive observer is designed to estimate the unavailable high-order derivative of the output. Then, a new dynamic terminal sliding surface is proposed with a state filter, which aims to develop the dynamic terminal sliding mode controller. By the composite adaptive control methods, a new adaptive law is designed, and the stability of the overall system is proofed based on the Lyapunov method. Finally, some numerical simulations are conducted to validate the effectiveness of the proposed algorithm.

Global fast dynamic terminal sliding mode control for a quadrotor UAV

A control method based on global fast dynamic terminal sliding mode control (TSMC) technique is proposed to design the flight controller for performing the finite-time position and attitude tracking control of a small quadrotor UAV. Firstly, the dynamic model of the quadrotor is divided into two subsystems, i.e., a fully actuated subsystem and an underactuated subsystem. Secondly, the dynamic flight controllers of the quadrotor are formulated based on global fast dynamic TSMC, which is able to guarantee that the position and velocity tracking errors of all system state variables converge to zero in finite-time. Moreover, the global fast dynamic TSMC is also able to eliminate the chattering phenomenon caused by the switching control action and realize the high precision performance. In addition, the stabilities of two subsystems are demonstrated by Lyapunov theory, respectively. Lastly, the simulation results are given to illustrate the effectiveness and robustness of the proposed control method in the presence of external disturbances.

Depth Control with Moving Weight for a Mini Underwater Vehicle

A new kind of depth control mechanism (DCM), which applies a moving weight (MW) to adjust its output torque, is designed for a mini underwater vehicle to overcome its problem of insufficient vertical thrust. Motion of the mechanism and underwater vehicle are analyzed. Dynamic terminal sliding mode controller is used to control the displacement of the MW and the depth. Simulations show that the proposed DCM and its controller are effective and the system can reach the predefined depth.

A novel dynamic terminal sliding mode control of uncertain nonlinear systems

A new dynamic terminal sliding mode control (DTSMC) technique is proposed for a class of single-input and single-output (SISO) uncertain nonlinear systems. The dynamic terminal sliding mode controller is formulated based on Lyapunov theory such that the existence of the sliding phase of the closed-loop control system can be guaranteed, chattering phenomenon caused by the switching control action can be eliminated, and high precision performance is realized. Moreover, by designing terminal equation, the output tracking error converges to zero in finite time, the reaching phase of DSMC is eliminated and global robustness is obtained. The simulation results for an inverted pendulum are given to demonstrate the properties of the proposed method.