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To tackle the trajectory tracking issue of nonlinear systems with unknown dynamics and input/output (I/O) constraints, a novel model‐free adaptive constrained control (MFACC) scheme is first proposed with improvement of tracking precision and reduction of computation cost. The system model is processed via the compact form dynamic linearization approach. Then, an event‐triggered observer‐based pseudo partial derivative (PPD) estimation algorithm is proposed to implement the data‐driven modeling information, which relieves the computation burden of modeling. Relying on the reconfigured data model, an improved prescribed performance control (PPC) approach with asymmetric predefined boundaries and the fractional order sliding mode control strategy are both exploited and integrated with MFACC for high‐precision and robustness assurance. Moreover, a novel prescribed‐boundary‐based event‐triggered mechanism is proposed to implement MFACC scheme so that the remarkable balance between tracking precision and computation cost can be maintained, and the I/O constraints can be handled via the proposed PPD‐based anti‐windup compensator and PPC technique. Finally, the stability analysis and contrast simulation are pursued which verifies the validity of proposed scheme. [ABSTRACT FROM AUTHOR]

To further improve the fast and stability of the control system of an indirect matrix converter (IMC) driven permanent magnet linear synchronous motor (PMLSM), a nonsingular fast terminal sliding mode control (NFTSMC) algorithm based on the disturbance observer of stochastic configuration networks (SCNs) is proposed. The NFTSMC algorithm is used to design the outer loop controller, which can reduce the influence of the IMC by the power supply voltage and high-frequency harmonics generated by switching. To further reduce the disturbance of IMC-PMLSM during operation, in this paper, a nonlinear disturbance observer based on SCNs is constructed, which solves the drawback that the traditional disturbance observer needs to adjust the parameters frequently under different working conditions. Finally, a simulation model is established on the MATLAB/Simulink platform to verify the effectiveness and advantages of the proposed control method. [ABSTRACT FROM AUTHOR]

Due to the lack of inertia and damping in the distributed power system with power electronic devices as interface, the stability of the power system will be adversely affected when the distributed power system is connected to the grid. In order to solve the problem of low inertia and improve stability, an adaptive terminal sliding mode control method based on the electromagnetic transient characteristics of virtual synchronous generators is proposed. During the design process, projection operators and parameter adaptive law control methods are introduced to compensate for parameter errors caused by environmental interference. Furthermore, by utilizing a prescribed performance function, the terminal sliding surface of the system will have the desired dynamic response, and variations of the system tracking error can be restricted. Simulation results show that the proposed controller has improved control accuracy and response speed, frequency stability, and power response. [ABSTRACT FROM AUTHOR]

This paper focuses on the problem of load frequency control and sensor fault-tolerant control in the multiarea power grid. To solve these problems, a sliding mode control strategy based on an interval observer is designed. First, an interval observer is designed to obtain the boundary estimation information of the system state online, which is used to reconstruct the load disturbance online. Based on the reconstructed values, an integral sliding mode controller is designed to keep the system frequency stable when the load is disturbed. Then, sensor fault is diagnosed by interval residual. An augmented observer is designed to estimate sensor fault online by equivalent transformation, and the sensor fault is compensated by the fault estimation to reduce the influence of fault on system performance and ensure the reliable and stable operation of the power system. The simulation results show the superiority of the proposed control strategy. [ABSTRACT FROM AUTHOR]

This paper puts forward a projection-based adaptive command filtered fuzzy nonsingular terminal sliding mode backstepping (PACFTB) control method for the speed control of the linear induction motor (LIM) with unknown end effects. Firstly, the technique of fuzzy logic systems (FLS) is investigated to approximate the nonlinear components of the LIM's mathematical model, which reduces the difficulty and cost of controller design. Then, a constrained command-filtered backstepping controller is designed with a filtering compensator compensating for the inherent error of constrained filter. Moreover, the nonsingular terminal sliding mode control method is combined in the controller design for its advantages of finite-time convergence of the system, and the projection-operator-based adaptive laws are established at the same time. Finally, the stability analysis proves that the boundedness and stability of all signals can be ensured with the proposed PACFTB controller, and the simulation results along with experiment results verify that the proposed control strategy has better control performance than the conventional command filter backstepping and PI controller. [ABSTRACT FROM AUTHOR]

This paper investigates an anti-disturbance sliding mode control strategy for a rigid satellite system with external disturbance under the prescribed performance constraints. An interval observer is firstly introduced to generate the interval estimation of the attitude angular velocity. Then a finite time identical disturbance reconstruction strategy is developed by using the interval estimation. Based on the novel performance function and error transformation constraints, the attitude tracking error is converted into a new error system that guarantees the desired transient and steady-state responses for the tracking error. Then, by introducing the reconstructed disturbance, a finite time anti-disturbance controller is constructed with the backstepping method. The stability of the strategy is guaranteed by the Lyapunov stability method. Finally, simulation results demonstrate the effectiveness of the proposed approach. • Proposed an interval observer for the rigid satellite attitude system. • Proposed an interval-estimation-based identical disturbance reconstruction method. • Proposed a finite time backstepping prescribed performance controller for the system. [ABSTRACT FROM AUTHOR]

This study investigates a finite‐time fault‐tolerant control scheme for a class of non‐affine nonlinear system with actuator faults and unknown disturbances. A global approximation method is applied to non‐affine nonlinear system to convert it into an affine‐like expression with accuracy. An adaptive terminal sliding mode disturbance observer is proposed to estimate unknown compound disturbances in finite time, including external disturbances and system uncertainties, which enhances system robustness. Controllers based on finite‐time Lyapunov theory are designed to force tracking errors to zero in finite time. Simulation results demonstrate the effectiveness of proposed method. [ABSTRACT FROM AUTHOR]

As a kind of special motors, linear induction motors (LIM) have been an important research field for researchers. However, it gives a great velocity control challenge due to the complex nonlinearity, high coupling, and unique end effects. In this article, an improved model-free adaptive sliding-mode-constrained control method is proposed to deal with this problem dispensing with internal parameters of the LIM. Firstly, an improved compact form dynamic linearization (CFDL) technique is used to simplify the LIM plant. Besides, an antiwindup compensator is applied to handle the problem of the actuator under saturations in case during the controller design. Furthermore, the stability of the closed system is proved by Lyapunov stability method theoretically. Finally, simulation results are given to demonstrate that the proposed controller has excellent dynamic performance and stronger robustness compared with traditional PID controller. [ABSTRACT FROM AUTHOR]

In this paper, a new model-free adaptive integral sliding-mode-constrained control scheme is presented for autonomous four-wheeled mobile vehicle (4WMV) parking systems. The proposed control strategy includes: 1) online identification for the object model based on a data-driven technique is presented for 4WMV and 2) an integral sliding-mode controller with control input constraints and stability analysis is provided. For online data-driven model identification, a compact-form dynamic linearization-based observer formulation is constructed for 4WMV. For integral sliding-mode controller design, a dynamic antiwindup compensator is introduced to solve integral saturation and actuator saturation problems in the autonomous 4WMV parking system. The designed control scheme only utilizes the body angle and steering angle of the vehicle under the condition that the precise mechanism model of the autonomous 4WMV parking system is not available to us. Finally, simulation comparisons between the model-free adaptive integral sliding-mode-constrained control scheme, PID control, and model-free adaptive control algorithms with coordinate compensation are given for two different vehicles. The simulation results show that a better control performance is achieved with the proposed new sliding-mode controller than the traditional control method when actuator or control input saturation exists in the autonomous 4WMV parking system. [ABSTRACT FROM PUBLISHER]

In this paper, a fault-tolerant control scheme based on a second-order dynamic terminal sliding mode is proposed for a near-space vehicle attitude dynamical system in the presence of actuator faults, model parameter uncertainties and external disturbances. The principle of the proposed dynamic terminal sliding mode scheme is firstly introduced. Then, a near-space vehicle attitude faulty model with parameter uncertainty is established. Furthermore, two dynamic terminal sliding mode controllers are designed for the inner and outer loops. It is shown that the proposed algorithm can reduce chattering phenomenon and guarantee system stability and asymptotic state tracking. Finally, simulation results are provided to demonstrate the performance of the proposed fault-tolerant control scheme. [ABSTRACT FROM PUBLISHER]

An observer-based sliding mode fault-tolerant controller is developed in this paper, which is applied to an interconnected power system with a hybrid energy storage system (HESS). The model of the interconnected power system with HESS is introduced first. An observer is then proposed to estimate the unknown but bounded load disturbances and the actuator fault. The sliding mode fault-tolerant controller is further designed based on the observer ensuring that the area control error of the interconnected power system asymptotically converges to zero. The stability and the convergence of the whole system are proven based on the Lyapunov stability theory. Finally, the effectiveness of the proposed fault-control scheme is demonstrated through simulations. [ABSTRACT FROM AUTHOR]

To address the issue of DC bus voltage fluctuation in an integrated power system aboard ships, this paper designs a prescribed-performance-based adaptive fractional-order sliding mode controller that ensures rapid convergence and maintains voltage stability, thereby enhancing the overall performance of the system. Firstly, a hybrid energy storage system is introduced into ship DC microgrid to meet the load demand in different scenarios. Then, taking into account the response time requirements of the ship's power grid, the prescribed performance function is set up to ensure that the tracking error of the DC bus voltage strictly converges at the specified speed and range. Meanwhile, fractional-order sliding mode surfaces are designed to reduce voltage chattering and achieve better tracking performance in conjunction with prescribed performance control. Considering the uncertainty of parameters in the model, the adaptive law based on the projection operator is used to estimate the unknown parameters in real time. The effectiveness of the proposed method has been verified through simulation and hardware-in-the-loop experimental results. • Hybrid energy storage system with batteries and supercapacitors integrated into ship DC microgrids, using a novel fractional order sliding mode backstepping controller to enhance robustness. • Prescribed performance control limits ship power system responses, reducing reliance on sliding mode surface selection, minimizing bus voltage chattering, and ensuring system responsiveness and steady-state error. • Algorithm uses adaptive law with projection operator to estimate parameters in real-time, mitigating aging or environmental changes' impact on ship microgrid control, enabling diverse applications. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of accurate speed tracking control of electric vehicles powered by permanent magnet synchronous motor (PMSM) under external load torque disturbance. Firstly, the dynamic model of PMSM is given, and the controller is designed based on backstepping control. Secondly, a second-order sliding mode differentiator is used to approximate the derivative of virtual control law and solve the problem of explosion of complexity. Considering the load disturbance of PMSM in the actual operation due to road roughness, a novel disturbance observer is proposed to the estimate the load disturbance. In addition, in order to achieve prescribed tracking error performance, the prescribed-performance control is proposed to guarantee the tracking error within a given prescribed boundary. Finally, the finite-time stability of the system is proved, the simulation and real-time implementation results verify the effectiveness of the designed controller. • The fuzzy logic systems are used to approximate the nonlinear function of the system. • The PPC is proposed to guarantee the tracking error within a prescribed boundary. • The novel DO is introduced to estimate the load disturbance in the actual operation. • The SOSMD is used to approximate the derivative of the virtual control law. [ABSTRACT FROM AUTHOR]