Abstract:The problem of event-triggered fixed-time control (ETFTC) for state-constrained stochastic nonlinear systems is discussed in this article. Different from the Barrier Lyapunov Function (BLF)-based and Integral BLF (IBLF)-based schemes which rely on feasibility conditions (FCs), by introducing nonlinear statedependent functions (NSDFs), the asymmetric timevarying state constraints are handled without FCs . Combining with the fixed-time stable theory (FTST) and dynamic surface control (DSC) technique with fixedti… Show more
The aerial flexible-joint robot (AFJR) manipulation system has been widely used in recent years. To handle uncertainty, the input saturation and the output constraint existing in the system, a fixed-time observer-based adaptive control scheme, is proposed (FTOAC). First, to estimate the input saturation and disturbances from the internal force between the robot and the flight platform, a fixed-time observer is designed. Second, a tangent-barrier Lyapunov function is introduced to implement the output constraint. Third, adaptive neural networks are introduced for the online identification of nonlinear unknown dynamics in the system. In addition, a fixed-time compensator is designed in this paper to eliminate the adverse effects caused by filtering errors. The stability analysis shows that all the signals of the closed-loop system are bounded, and the system satisfies the condition of fixed-time convergence. Finally, the simulation results prove the superiority of the proposed control strategy by comparing it with the previous schemes.
The aerial flexible-joint robot (AFJR) manipulation system has been widely used in recent years. To handle uncertainty, the input saturation and the output constraint existing in the system, a fixed-time observer-based adaptive control scheme, is proposed (FTOAC). First, to estimate the input saturation and disturbances from the internal force between the robot and the flight platform, a fixed-time observer is designed. Second, a tangent-barrier Lyapunov function is introduced to implement the output constraint. Third, adaptive neural networks are introduced for the online identification of nonlinear unknown dynamics in the system. In addition, a fixed-time compensator is designed in this paper to eliminate the adverse effects caused by filtering errors. The stability analysis shows that all the signals of the closed-loop system are bounded, and the system satisfies the condition of fixed-time convergence. Finally, the simulation results prove the superiority of the proposed control strategy by comparing it with the previous schemes.
“…• Different from general researches considering stateconstrained for single physical systems [25,26], the states of the robots are constrained in a range for the IRSs in convergence process in this paper. The output state of each robotic does not exceed the upper bound or low bound.…”
This paper investigates the collaborative de-1 sign problem aiming to achieve state-constrained bipar-2 tite tracking of interconnected robotic systems (IRSs) 3 with prescribed performance. We propose a hierarchi-4 cal state-constrained estimator-based control frame to 5 reduce the complexity of algorithms and improve the 6 adaptation of the tracking control when the robotic-7 s are constrained to physical boundaries and external 8 environment. Without the pre-known tracking trajecto-9 ry, the estimator-based layer can estimate the tracking 10 trajectory at each time interval by the interconnected 11 topology. The position constraints are never violated 12 during the convergence process by designing of control 13 algorithms. The theoretical proof and simulation result-14 s are presented to validate the feasibility of the control 15 algorithms.
“…In light of this, accurate identification and modeling of nonlinear systems constitute the first key step for achieving robust analysis and optimization. The T-S fuzzy models provide a powerful tool for dealing with complex nonlinear models, enhancing the robustness and interpretability of the models, thus being widely applied in industrial control systems [21][22][23]. Fuzzy models leverage fuzzy rules to capture the subtle features of nonlinear relationships, enabling accurate modeling.…”
This study introduces an observer-based H∞ model predictive control strategy, designed for discrete-time nonlinear systems affected by bounded disturbances. Initially, an output-feedback control strategy is utilized to parameterize control actions over an infinite interval and to estimate the system state. This strategy is integrated into model predictive control (MPC) to achieve optimal control and state tracking within the closed-loop system. Subsequently, the Takagi-Sugeno (T-S) fuzzy logic model is employed to address the nonlinear terms of the system, and the H∞ performance index is used to mitigate the adverse effects of bounded disturbances on system output. With the assistance of Lyapunov stability theory and linear matrix inequalities (LMI) optimization method, sufficient conditions to ensure the system's asymptotic convergence are provided. To demonstrate the effectiveness of the proposed method, a numerical example and an engineering application example are presented.
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