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In this paper, the electrostatic actuator-based active vibration control of a single-wall carbon nanotube conveying fluid is studied. A double electrostatic actuator scheme is developed and its decoupling method also is proposed. Then, a novel adaptive sliding-mode control (SMC) scheme is developed. The newly proposed scheme future improves existing results from two aspects: (1) the newly proposed adaptive SMC can work well under high uncertain case in which all parameters are uncertain and the uncertainties cannot be separated from control force and (2) a double electrostatic actuators scheme which can suppress the vibration of carbon nanotube in multiple directions is designed, and a novel decoupling scheme for the two actuators is developed. The stability of the closed-loop system is analyzed by using Lyapunov stability theory. Finally, the simulation results illustrate the effectiveness of the proposed scheme.

This paper addresses the control problem of the flexible joint manipulator (FJM) with unmeasurable system states and mismatched uncertainties. First, the control system is transformed as a matched uncertain system with unmeasurable states based on differentiation method. Then, the uncertainties and unmeasurable states are estimated by designing a fixed-time observer (FTO). Based on the integral sliding-mode control (SMC), the bi-limit homogeneity technique and the estimation of FTO, a finite-time SMC is proposed for FJM. Compared with the existing finite-time SMC method for FJM, the most attractive feature of the proposed method is that not only the finite-time convergence is guaranteed but also the two angular velocity sensors for rotation angles of link and motor are simplified. Moreover, the proposed SMC can suppress the mismatched and matched uncertainties by using chattering-free control input. The fixed-time stability of FTO and finite-time stability of proposed controller are proved. Finally, the efficiency of proposed scheme is shown by the numerical simulation.

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This paper proposes a new spiking-free fixed-time disturbance observer (DO)-based sliding mode control (SMC) scheme of maximum power extraction for the wind turbine system. First, a fixed-time DO is developed by using uniform robust exact differentiator (URED). Then, an SMC scheme is proposed by using the estimation of fixed-time DO and designing a spiking-free function. The proposed spiking-free fixed-time DO-based SMC scheme exhibits three attractive features: first, compared with existing scheme, the proposed scheme can guarantee the fast convergent performance under different initial system conditions based on the design of fixed-time stability. Second, by designing a novel spiking-free function, the potential spiking problem of fixed-time DO that occurs when observer gain is high and initial estimate states and initial true states are not equal is avoided. Third, the control input of proposed SMC is continuous, thus the undesirable chatter of conventional SMC is avoided. Finally, the attractive features of proposed scheme are illustrated based on simulation.