This paper considers the problem of finite-time adaptive fuzzy prescribed performance control via output-feedback for nonstrict-feedback nonlinear systems. The fuzzy state observer is designed to estimate the unmeasured system states. To rapidly approximate the derivative of virtual signal, a novel finite-time command filter is proposed. The fractional power error compensation mechanism is established to remove filtered error. By integrating the prescribed performance control and command filter technique into backstepping recursive design, a finite-time adaptive output-feedback controller is constructed, and the stability of closed-loop system is strictly proved. The designed control strategy shows that the closed-loop system is practical finite-time stable, and the output tracking error converges to a residual set within prescribed performance bound in finite time. Finally, a numerical comparison and a practical examples are provided to demonstrate the validity of the developed finite-time control algorithm.

In this article, the problem of finite-time adaptive fuzzy tracking control for multi-input and multi-output (MIMO) nonlinear systems with input saturation is investigated. The new finite-time command filter is introduced for generating command signals and their derivatives to work out the matter of “explosion of complexity,” and the modified fractional power-based error compensation mechanism (ECM) serves as removing the effect of filter error. Then, the finite-time adaptive control scheme is established via the backstepping recursive design technique. It guarantees all the signals of the closed-loop system (CLS) are finite-time bounded while the output tracking errors are regulated to a sufficiently small neighborhood of the origin in finite time. Finally, the effectiveness of the proposed finite-time control scheme is verified by a numerical comparison example.

This brief focuses on the problem of fixed-time adaptive trajectory tracking control for a quadrotor unmanned aerial vehicle (QUAV) subject to error constraints. By virtue of the fixed-time command filter, the phenomenon of “explosion of complexity” (EOC) existing in the conventional backstepping method is successfully eliminated, meanwhile the effect of filtered error is skillfully removed via a new fractional power error compensation mechanism. By combining the prescribed performance control and backstepping design method together with command filter technique, a fixed-time adaptive control strategy is established. It is proved that all signals of the closed-loop system are fixed-time bounded, and the position and attitude tracking errors of the QUAV approach to an arbitrarily small region of the original point within the predefined performance bounds in a fixed time. Finally, simulation results are given to show the availability of the presented fixed-time control algorithm.

This paper devises a fixed-time distributed adaptive formation control algorithm under the event-triggered framework to guarantee the expected formation pattern for multiple quadrotor unmanned aerial vehicles (QUAVs) with full-state constraints. The multiple QUAVs subject to full-state constraints are transformed into the ones that are free from any constraints via a time-varying nonlinear transformation function (NTF), which is effective to handle the case regardless of whether there exist state constraints. The issue of “explosion of complexity” (EOC) as well as singularity problem are fully coped via the fixed-time command filter and the smooth switch function, respectively. To further improve the control performance of multiple QUAVs, the nonsmooth error compensation mechanism is constructed to compensate the filtered error resulting from command filter. The rigorous stability analysis of the developed event-trigger-based distributed formation control scheme proves that all signals of the closed-loop system are fixed-time bounded, and the states of multiple QUAVs will not violate the prescribed constraints and the formation tracking errors converge to a small region around the origin in a fixed time. Finally, simulation examples are performed to delineate the validity of the proposed distributed formation control algorithm.

This article concentrates on the distributed fixed-time adaptive event-triggered attitude control problem for multiple quad-rotor unmanned aerial vehicles (QUAVs) with prescribed performance. By utilizing the fuzzy logic system and constructing a piecewise continuous function, the unknown nonlinear dynamics of multiple QUAVs and the problem of singularity are skillfully addressed, respectively. The command filter that has fixed-time convergence is devised to avert the “explosion of complexity” problem, while the impact of filtered error is eliminated by virtue of the fractional-power-based error compensation signals. Moreover, a fixed-time performance function is embedded into the distributed attitude control algorithm to ensure that the synchronization errors converge to the preassigned performance confines. It is strictly proved that all closed-loop signals are fixed-time bounded, and the disagreement errors are steered into a small region nearby the zero in a fixed time. Finally, numerical simulations are given to demonstrate the efficiency and superiority of the devised fixed-time control scheme. Note to Practitioners —This article aims at designing an event-triggered distributed attitude control algorithm to relax the communication burden for multiple QUAVs subject to external disturbances. In practical applications, the communication bandwidth and the onboard energy of QUAVs are limited, while the traditional time-triggered approaches neglect these realistic restrictions. Thereby, by incorporating a relative threshold event-triggered mechanism into the command filtered backstepping design process, not only can the “explosion of complexity” issue and the impact of filtered error be surmounted, but also the frequency of controller updating is reduced. Additionally, the construction of a prescribed performance function with fixed-time convergence results in the improvement of both transient and steady-state performances for multiple QUAVs, thus meeting practical requirements more effectively.

The globally finite-time control issue is concerned in this note for high-order nonlinearly parameterized systems with unknown control gain and external disturbances. A novel control strategy combining adaptive control technique with sign function can well deal with serious uncertainties and unknown control gain. Without any nonlinear growth assumptions, a unified and systematic design procedure is employed to derive an adaptive state-feedback controller with the help of the adding a power integrator method and backstepping technique. Then, by finite-time stability analysis and Lyapunov functions, the proposed controller ensures that the closed-loop system is globally practically finite-time stable (PFTS). Two simulation examples, including a mass-spring mechanical system and a numerical example, are applied to verify the performance and effectiveness of the designed schemes.