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This manuscript describes the design of a controller that assures predefined-time convergence in fractional-order sliding mode control (PTFOSMC) for a quadrotor UAV subjected to matched perturbation. Moreover, predefined-time techniques enable the establishment of a time constraint for convergence as a control parameter, distinguishing them from finite- and fixed-time controllers. The proposed control offers the advantage of sliding mode control, exhibiting rapid response and robust performance for the quadrotor subsystems. Notably, the suggested controller is devoid of terms dependent on the initial conditions of the quadrotor. Additionally, an established switching-type predefined-time controller with fractional-order is introduced to bolster robustness against external disturbances and alleviate the chattering problem associated with the sliding mode technique. The application of the Lyapunov function is employed to analyze the predefined-time stability of the quadrotor utilizing the suggested PTFOSMC. Numerical results are provided to demonstrate the effectiveness of the suggested scheme. [ABSTRACT FROM AUTHOR]

This paper presents a predefined-time fractional-order control for a quadrotor system subjected to perturbations. First, a fractional-order sliding manifold is proposed to ensure a predefined-time convergence of the tracking error. Second, a fractional-order switching-type predefined-time controller is proposed to achieve robustness against external disturbances. The predefined stability/convergence are proved using Lyapunov functions. The proposed method is validated using an adequate scenario and compared to other controllers to show the feasibility and superiority of the proposed one. [ABSTRACT FROM AUTHOR]

The present study addresses the problem of fixed-time stabilization (FTS) of mobile robots (MRs). The study's distinguishing aspects are that the system under examination is subjected to external disturbances, and the system states are pushed to zero in a finite time. This paper suggests new control techniques for chained-form nonholonomic systems (CFNS) subjected to disturbances. First, a switching fractional-order (FO) control approach is proposed for a first-order subsystem (FOS) of an MR under complex disturbances. Secondly, an FO generic global sliding mode control approach is designed for the second-order system (SOS) of the MR in the presence of disturbances. The suggested sliding manifold for the SOS of the MR guarantees global system stability and reduces the chattering problem during control operations. A conventional quadratic Lyapunov function (QLF) is used to converge to the origin in a finite time (FnT). Through this study, a stabilizer for an MR in the presence of disturbances based on an FO switching time-varying controller that can stabilize immeasurable states in a fixed time is proposed. Finally, three case simulations are provided to demonstrate the efficacy of the control strategy proposed in this work against external disturbances. [ABSTRACT FROM AUTHOR]

This paper is dedicated to controlling the speed of the double star induction machine (DSIM) by a robust controller. The model of DSIM has been presented by using a vector representation. To control this machine, three robust nonlinear controllers have been used: an active disturbance rejection control (ADRC) regulator is presented in the first place, after a sliding mode control (SMC) is studied in second place, to achieve some performance for the machine, and then followed by the proposed robust controller based on the Backstepping (BSC) technique, this technique is based on the stability of the Lyapunov function. A comparative study between these controllers (ADRC, SMC and BSC) has been presented. The performance of three regulators or three techniques is evaluated under the normal operating condition of the machine and in the presence of one current sensor fault. The simulation of these techniques is presented, the results showed that the proposed controller based on BSC is more robust than that of ADRC Controller and SMC controller. [ABSTRACT FROM AUTHOR]