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In this paper, the finite time tracking control issue of the TCP/AQM system with input saturation and non-response flows such as UDP is studied. A novel AQM control algorithm is proposed by combining finite time control, prescribed performance control and fuzzy logic system. In order to obtain better disturbance suppression performance, the fuzzy logic system is adopted to deal with the external disturbance and the error disturbance generated by approximate input saturation function. The controller is designed to ensure that the queue tracking error converges to a specific region and achieve the practical finite time stability of all signals in the closed-loop system. The simulation results demonstrate the feasibility and superiority of the proposed method. [ABSTRACT FROM AUTHOR]

The problem of finite-time attitude-tracking control (ATC) for a rigid spacecraft subject to inertial uncertainties, external disturbances, actuator saturations and faults is addressed. First, a fast nonsingular terminal sliding mode (FNTSM) manifold is constructed to improve robustness. Second, the fuzzy logic system (FLS) is integrated into the manifold derivative to deal with the lumped unknown function. The specific assumptions about uncertainties in most of the existing achievements are no longer needed. Combining the FNTSM and fuzzy approximation techniques, an enhanced fault-tolerant control scheme is developed. Compared to almost all finite-time ATC results based on FLS or neural network, a new Proof line is proposed to prove that the approximation errors are finite-time stable instead of asymptotically stable. Therefore, the attitude controller presented herein guarantees the real finite-time stability in a complete sense. Finally, numerical experiments are conducted to verify the effectiveness of the solution, and comparisons with related works are displayed. • Assumptions on uncertainties in the existing achievements are abolished. • Finite-time stability of fuzzy approximation errors is proved via a new Proof line. • Norm approximation is exploited to reduce the parameters to be estimated online. • The attitude controller guarantees the finite-time stability in a complete sense. [ABSTRACT FROM AUTHOR]

For the nonlinear TCP/AWM network congestion control system with external disturbances, under the framework of backstepping control method, an adaptive network congestion control strategy based on event-triggered mechanism is proposed. This strategy reduces the waste of network resources by introducing an event-triggered mechanism and uses RBF neural network to deal with external disturbances. The Lyapunov theory is used to prove that all signals in the closed-loop system are bounded. Finally, the proposed method is verified by simulation and is compared with PID, which further verifies the effectiveness of the proposed control method. [ABSTRACT FROM AUTHOR]

This article investigates the adaptive fuzzy prescribed time H ∞ congestion control problem for a class of high speed transmission control protocol/active queue management (HSTCP/AQM) systems subject to asymmetric input saturation and external disturbance. Firstly, a saturation-based finite-time performance function (SFTPF) is constructed by introducing a nonnegative modified signal associated with input saturation errors into user-defined performance boundaries, which features the capability of ensuring the user-appointed tracking performance when no saturation exists and degrading it once saturation occurs, thereby effectively increasing the flexibility and reliability of the control scheme. Then, by designing a novel shifting function, the condition that the initial value of the queue tracking error remains within that of SFTPF is relaxed, which avoids the SFTPF being redeveloped for different initial queue tracking errors. Thereafter, an auxiliary system and H ∞ control theory are employed to eliminate the adverse effect caused by input saturation and external disturbance, respectively. Moreover, through the Lyapunov stability analysis, it is proven that, under our proposed adaptive fuzzy congestion control scheme, all the closed-loop signals are bounded, and the connection between input saturation and performance-related constraint is established. Finally, a set of simulation results are presented to demonstrate the feasibility and effectiveness of the designed congestion controller. • A new shifting function is developed to relax the initial condition restriction. • An error transformation function is designed to solve asymmetric constrained issues. • The performance constraint boundaries can be resiliently enlarged and recovered. • An adaptive fuzzy practical prescribed time congestion control scheme is proposed. [ABSTRACT FROM AUTHOR]