This paper reports our study on the issue of finite-time adaptive fuzzy tracking control for a class of uncertain nonlinear systems with prescribed performance. A novel finite-time prescribed performance control approach, in which fuzzy systems are employed to approximate completely unknown nonlinear functions, is proposed by incorporating the technique of prescribed performance control with the method of command filtered design. Based on the finite-time stability theory, all the signals of the closed-loop system can be bounded and the output tracking error can converge to a prescribed small region within a finite-time by the proposed scheme; meanwhile, the problem of complexity explosion can be avoided. The effectiveness of the presented method is verified by two examples.

This note investigates the problem of global output feedback stabilization for a class of nonlinear systems with unknown measurement sensitivity. A new design method, namely dual-domination approach, is proposed to explicitly construct a state observer as well as an output feedback control law, which globally asymptotically stabilizes the nonlinear systems. The novelty of this note owes to a distinct perspective in coping with unknown measurement sensitivity which has previously been a hurdle to solve the global output feedback stabilization problem of the nonlinear systems.

This study concentrates on the tracking control problem for nonlinear systems subject to actuator saturation. To improve the performance of the controller, we propose a fixed-time tracking control scheme, in which the upper bound of the convergence time is independent of the initial conditions. In the control scheme, first, a smooth nonlinear function is employed to approximate the saturation function so that the controller can be designed under the framework of backstepping. Then, the effect of input saturation is compensated by introducing an auxiliary system. Furthermore, a fixed-time adaptive neural network control method is given with the help of fixed-time control theory, in which the dynamic order of controllers is reduced to a certain extent since there is only one updating law in the entire control design. Through rigorous theoretical analysis, it is concluded that the proposed control scheme can guarantee that: 1) the output tracking error can converge to a small neighborhood near the origin in a fixed time and 2) all signals in the closed-loop system are bounded. Finally, a numerical example and a practical example based on the single-link manipulator are provided to verify the effectiveness of the proposed method.

This paper studies the global stabilisation problem for a class of high-order nonlinear systems with multiple time delays. A distinct property of the systems to be investigated is that powers on the upper bound restrictions of nonlinearities are allowed to take values on a continuous interval. By introducing the sign functions and using the generalised method of adding a power integrator, this paper successfully designs a continuous global state-feedback controller independent of time delays. Moreover, a novel Lyapunov–Krasovskii functional is constructed to prove the globally asymptotic stability of the resulting closed-loop system.

This paper aims to solve two intricate problems in nonlinear control: the singularity caused by driving the control to infinity at the prescribed time and the stabilization via adaptive event-triggered feedback for a class of uncertain nonlinear systems with asymmetric time-varying output constraints. The difficulty is how to dominate the implicit time in the system and the parameter error multiplied by an adaptive law without breaking the time-varying output constraint. To overcome the difficulty, we develop an event-triggered adaptive stabilizing controller comprising a time-varying scaling function and an exponential decay term, which is bounded on the whole-time interval and ensures that the states converge to the origin after entering a prescribed compact set within a prescribed finite time. Superior to the existing event-triggered schemes, the new triggered rule with a time-varying threshold guarantees that the designed controller is not only more robust against more serious uncertainties but also unifies the design in dealing with both constrained and unconstrained systems without constructing barrier functions associated with the output constraint. Finally, a practical simulation example is provided to illustrate and verify the effectiveness of the proposed approach.