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This paper presents a novel control framework for enhancing the attitude stabilization of multirotor UAVs using Control Moment Gyros (CMGs) and a Disturbance Robust Drive Law (DRDL). Due to their lightweight and compact structure, multirotor UAVs are highly susceptible to disturbances such as wind, making it challenging to achieve stable attitude control using rotor thrust alone. To address this issue, we employ CMGs to provide robust attitude control and apply Fast Terminal Sliding Mode Control (FTSMC) to ensure fast and accurate convergence within a finite time. The combination of CMGs' torque amplification capability with the DRDL enables the system to effectively avoid singularities and maintain stable control performance in the presence of disturbances. Simulation results demonstrate that the CMG-equipped hexarotor utilizing the DRDL rapidly converges to the target attitude despite external disturbances, while minimizing oscillations in both motor speed and gimbal movement. Additionally, compared to the pseudo-inverse control method, the proposed approach significantly improves singularity avoidance and disturbance mitigation. The proposed control framework enhances the stability and reliability of UAV operations and demonstrates its potential for high-performance control in challenging disturbance environments.

To overcome the sensitivity of voltage source inverters (VSIs) to parameter perturbations and their susceptibility to load variations, a fast terminal sliding mode control (FTSMC) method is proposed as the core and combined with an improved nonlinear extended state observer (NLESO) to resist aggregate system perturbations. Firstly, a mathematical model of the dynamics of a single-phase voltage type inverter is constructed using a state-space averaging approach. Secondly, an NLESO is designed to estimate the lumped uncertainty using the saturation properties of hyperbolic tangent functions. Finally, a sliding mode control method with a fast terminal attractor is proposed to improve the dynamic tracking of the system. It is shown that the NLESO guarantees convergence of the estimation error and effectively preserves the initial derivative peak. The FTSMC enables the output voltage with high tracking accuracy and low total harmonic distortion and enhances the anti-disturbance ability.

A multi-axis gimbal tracking device is necessary for the micro spacecraft to detect the target. The movement of the tracking device can generate a marked impact on its carrier in the microgravity environment, which should be taken into account when high accuracy is required. The model of the micro spacecraft and the gimbal tracking device can be regarded as a multi-axis open-chain manipulator composed of rigid bodies and joints. Then the dynamics of the model is established by the twist-wrench formulation. A novel dual-loop integral-type fast terminal sliding mode control scheme is proposed to improve the attitude tracking performance of the micro spacecraft. The attitude dynamics of the micro spacecraft is decomposed into two parts, which are used to design controllers to track the angle and the dummy angular velocity signals, respectively. An adaptive disturbance observer is designed to estimate and compensate for the external disturbance. To maintain high positioning accuracy and restrict excessive control torque, a modified nonsingular fast terminal sliding mode controller is proposed for the gimbal tracking device. Accordingly, the proposed schemes have the advantages of nonsingularity, fast convergence, good robustness, and high tracking accuracy. The simulation results demonstrate the feasibility of the modeling method and the effectiveness of the control schemes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 ISA. Published by Elsevier Ltd. All rights reserved.)

This research article presents a process control application of a single-input single-output (SISO) level control system using the combination of fast terminal sliding mode control (FTSMC) and optimization method. Non-dominated sorted genetic algorithm-ii (NSGA-ii); a modern optimization technique is used to optimized the parameters of FTSMC. Here, a comparative analysis of conventional sliding mode control (SMC), FTSMC, NSGA tuned FTSMC and NSGA-ii tuned FTSMC has being carried out through MATLAB/ Simulink. The performance indices such as integral absolute error (IAE), integral square error (ISE), and integration of weighted errors have been considered as the objective functions. The robustness of the controller is tested through real-time experimentation. The stability is obtained by using Lyapunov stability criteria. Simulation and experimental results show that NSGA-ii tuned FTSMC method outperforms the conventional methods and the error is converging to zero in a finite-time. Also, NSGA-ii tuned FTSMC provides better-estimated setpoint and disturbance rejection responses., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 ISA. Published by Elsevier Ltd. All rights reserved.)

This paper proposes an adaptive neural network based output feedback backstepping fast terminal sliding mode control (NN-BFTSMC) for continuous polymerization reactor with external disturbances and parametric uncertainties. Firstly, neural networks (NN) are employed to approximate the uncertain nonlinear functions. Next, the average molecular weight and the reactor temperature tracking controllers are designed based on the finite-time NN-BFTSMC. In addition, the NN-BFSMC effectively estimates and compensates the upper bounds of the external disturbances. Moreover, the chattering effect is eliminated without losing the robustness accuracy. The finite-time stability of the closed-loop system is proved by Lyapunov theory. At last, numerical simulations and comparative studies are introduced to illustrate the superior performance of the proposed method., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 ISA. Published by Elsevier Ltd. All rights reserved.)

In this paper, a fast terminal sliding mode control (FTSMC) scheme with double closed loops is proposed for the spacecraft attitude control. The FTSMC laws are included both in an inner control loop and an outer control loop. Firstly, a fast terminal sliding surface (FTSS) is constructed, which can drive the inner loop tracking-error and the outer loop tracking-error on the FTSS to converge to zero in finite time. Secondly, FTSMC strategy is designed by using Lyaponov's method for ensuring the occurrence of the sliding motion in finite time, which can hold the character of fast transient response and improve the tracking accuracy. It is proved that FTSMC can guarantee the convergence of tracking-error in both approaching and sliding mode surface. Finally, simulation results demonstrate the effectiveness of the proposed control scheme., (© 2013 ISA. Published by Elsevier Ltd. All rights reserved.)