Explore the vast range of titles available.

This paper considers the finite-time and fixed-time synchronization of delayed complex-valued recurrent neural networks (CVRNNs) with discontinuous activation functions and nonidentical parameters via sliding mode control. Firstly, we design a sliding surface involving integral structure and a discontinuous control. Secondly, by constructing Lyapunov functional and using the differential inequality technique, some sufficient conditions are derived to guarantee the finite-time and fixed-time synchronization of delayed complex-valued recurrent neural networks with discontinuous activation functions and nonidentical parameters. Finally, two simulation examples are shown to illustrate the proposed methods.

In this paper, a novel discrete terminal integral sliding-mode backstepping control (DTISM-BSC) is proposed for the surface-mounted permanent magnet synchronous motor (SMPMSM) drive system, which improves the speed tracking performance and robustness of the system. In this control scheme, the discrete ultra-local model (ULM) of the SMPMSM drives, which employs the algebraic parameter identification technology to handle the unknown disturbance and parametric uncertainties, is first set up. Then, the terminal integral sliding-mode surface is proposed for its advantages of finite-time convergence to achieve speed rapid tracking, in which the control performance of backstepping control is improved. Thirdly, the equivalent control law is combined with the designed switching law to construct the speed controller based on the ULM. In this case, the bounded function is adopted to improve chattering problem. Meanwhile, the asymptotic stability and rapid convergence is verified. Finally, the experimental comparisons between the proposed method and the non-singular terminal sliding mode backstepping control (NTSM-BSC) are developed to validate the effectiveness of the proposed DTISM-BSC.

In this article, we focus on a suspension active magnetic bearing system that majorly experiences many disturbances. First, we construct a complete model of a suspension active magnetic bearing system composed of conventional proportional–integral–derivative controllers with two kinds of inputs and a robust control method, known as the sliding mode control method. On certain proportional–integral–derivative controllers, the sliding mode control method is used to control linear or nonlinear systems while a chattering phenomenon occurred in each time period. This chattering is due to the high-frequency characteristic of this control method, but it was represented a major disadvantage. Therefore, we propose these techniques for reducing much of this chattering, and then we also propose a fuzzy controller as the control model. In regard to the sliding mode, the fuzzy controller of input and output signals approximates the signals of the proportional–integral–derivative and sliding mode control controller outputs. We also replace the signum function from the saturation function and use the MATLAB Simulink programming environment in our design work. Finally, we compare the average and maximum tracking errors with those of a method proposed by Lin et al. and find that the results of our proposed control method tracks very well with the sinusoidal input signal and also much better than the other method.

This paper proposes a new dynamic PID sliding mode control technique for a class of uncertain nonlinear systems. The offered controller is formulated based on the Lyapunov stability theory and guarantees the existence of the sliding mode around the sliding surface in a finite time. Furthermore, this approach can eliminate the chattering phenomenon caused by the switching control action and can realize high-precision performance. Moreover, an adaptive parameter tuning method is proposed to estimate the unknown upper bounds of the disturbances. Simulation results for an inverted pendulum system demonstrate the efficiency and feasibility of the suggested technique.

The problem of sliding-mode control (SMC) with dissipativity for a class of time-delay Takagi–Sugeno fuzzy singular systems is investigated. The system is subject to uncertainties and input non-linearity. Based on an integral sliding surface, a delay-dependent criterion is developed in terms of linear matrix inequalities, which ensures the sliding mode dynamics to be robustly admissible and strictly (𝓆𝓈𝓇)-dissipative. Moreover, an SMC law is established such that the reachability of the specified sliding surface is guaranteed. Finally, the validity and applicability of the proposed approach are illuminated by two simulation examples.

This paper develops a sliding-mode control with an improved nonlinear extended state observer (SMC-INESO) for the rotation system of a hydraulic roofbolter with dead-zones, uncertain gain, and disturbances, with the purpose of improving tracking performance. Firstly, the rotation system is modeled to compensate for dead-zone nonlinearity. Then, we present an improved nonlinear extended state observer to estimate disturbances of the rotation system in real time. Moreover, a proportional-integral-differential sliding-mode surface is introduced and an improved sliding-mode reaching law is designed. Based on this, a sliding-mode control law is developed. In order to eliminate the influence of estimation error and uncertain gain, we design two adaptation laws based on the sliding-mode surface and the estimated states. Finally, the effectiveness of the proposed SMC-INESO is verified through comparative simulation studies.

This study proposes a novel hierarchical nonlinear proportional-integral fast terminal sliding mode (HNLPIFTSM) control for permanent magnet synchronous motor (PMSM) speed regulation system. A new type of sliding surface called HNLPIFTSM surface, which combines the benefits of a nonlinear proportional-integral (PI) sliding mode surface and a fast terminal sliding mode (FTSM) surface, is proposed to enhance the robustness and improved the dynamic response, whilst preserving the great property of the conventional hierarchical fast terminal sliding mode (HFTSM) control strategy. The proposed HNLPIFTSM surface uses the novel nonlinear PI sliding mode surface as its inner loop and uses the FTSM surface as its outer loop. Meanwhile, an extended state observer (ESO) is used to estimate the uncertain terms of the PMSM speed regulation system. Furthermore, the stability of the closed-loop control system under the ESO and the HNLPIFTSM control strategy is proved by the Lyapunov stability theorem. Finally, the simulations and experimental demonstrations verify the effectiveness and superiorities of our proposed HNLPIFTSM control strategy over the conventional HFTSM control strategy.

This paper presents a new nonsingular fast terminal sliding mode back-stepping control (BSC) for uncertain nonlinear systems subjected to unknown mismatched disturbance based on an adaptive super-twisting sliding mode nonlinear disturbance observer (ASTSM-NDO). The proposed algorithms utilize BSC technique to manage high-order uncertainty systems by compounding the dynamic surface control (DSC) architecture to get rid of ‘complexity explosion’. To cope with the unknown upper-bound mismatched disturbance, an adaption law is devised by finite time stability ASTSM-NDO designation. Besides, in the last step, the actual control scheme is designed by an integral nonsingular fast terminal sliding mode control algorithms combined with disturbance estimation and uncertainty adaption law to eliminate the influence of modeling error and mismatched interference on systems. Lya-punov stability theory is applied to prove that the tracking deviation of the whole system is uniformly and ultimately bounded. Finally, two examples are simulated by comparing the derived outcomes with existing method to verify the effectiveness and feasibility of the devised methodology.

This paper presents an approach of achieving high performance and robustness for matched uncertain multi-input multi-output linear systems with external disturbances and multiple state-delays, which are often encountered in practice and are frequently the sources of instability. This scheme is based on composite nonlinear feedback and integral sliding mode control methods. The selection of nonlinear function and the existence of sliding mode are two important issues, which have been addressed. The control law is designed to guarantee the existence of the sliding mode around the nonlinear surface, and the damping ratio of the closed-loop system is increased as the output approaches the set-point. Simulation results are presented to show the effectiveness of the proposed method as a promising way for controlling similar nonlinear systems.

Fuzzy logic control, due to its simple control structure, easy and cost-effective design, has been successfully employed to the application of guidance and control in robotic fields. This paper aims to review fuzzy-logic-based guidance and control in an important branch of robots—marine robotic vehicles. First, guidance and motion forms including the maneuvering, path following, trajectory tracking, and position stabilization are described. Subsequently, the application of three major classes of fuzzy logic control, including the conventional fuzzy control (Mamdani fuzzy control and Takagi–Sugeno–Kang fuzzy control), adaptive fuzzy control (self-tuning fuzzy control and direct/indirect adaptive fuzzy control), and hybrid fuzzy control (fuzzy PID control, fuzzy sliding mode control, and neuro-fuzzy control) are presented. In particular, we summarize the design and analysis process of direct/indirect adaptive fuzzy control and fuzzy PID control in marine robotic fields. In addition, two comparative results between hybrid fuzzy control and the corresponding single control are provided to illustrate the superiority of hybrid fuzzy control. Finally, trends of the fuzzy future in marine robotic vehicles are concluded based on its state of the art.