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In order to improve the shortcomings of the traditional constant section and gradual section space elevator system, combined with the advantages of constant section and gradual section space elevator system, a model of segmented space elevator system is designed. This model has the characteristics of easier construction, more practical functions, and easier maintenance. The cyclic iterative method is proposed to calculate the stress distribution of the space elevator system. The maximum stress variation and system scale variation of segmented space elevator system with different segment numbers is analyzed and compared with the system scale of constant section and gradual section space elevator system. The results show that the segmented space elevator model can significantly reduce the peak stress of the space elevator system under the condition of limited increase in the system scale, and the peak stress is 56% lower than that of the constant section space elevator model. Considering the number of segments, peak stress, and system scale, the calculation results show that the optimal number of segments is 5 or 6.

In this paper, an appointed time active vibration suppression controller is studied for flexible satellite with piezoelectric actuators. Firstly, a piecewise sliding mode controller with the appointed time is designed to guarantee that the attitude error converges at the appointed time. The convergence time of the model can be set with a prior parameter. Secondly, a modal observer is used to estimate the vibration of the flexible elastic modal, and an active vibration suppression controller is designed to converge at a predefined time. The stability of the two controllers is demonstrated by a Lyapunov theory. The Simulink simulation framework is eventually established, and the numerical simulation results of various data demonstrate the appointed time convergence of the proposed controller. Compared with adaptive sliding mode and nonsingular terminal sliding mode, the controller can achieve higher precision control with less energy consumption.