Global fixed-time emergency control of space robot under safety constraints

doi:10.16265/j.cnki.issn1003-3033.2025.12.1506

Abstract

Abstract:

In order to solve the safety constraint problem of uncertain space robot (USR) with time constraints and output constraints, a second-order sliding mode global fixed-time emergency control method was adopted. The dynamic model of the uncertain space robot was established by applying the momentum conservation theorem and Lagrangian method. To achieve the safety output goal, an obstacle Lyapunov function was introduced to limit the system error within the preset range. Based on this, the upper bound of the system's uncertain terms was estimated, and the system's time constraints were further considered. By using the power summation integration technique, a second-order sliding mode global fixed-time emergency controller was constructed. The results show that root-mean-square error(RMSE) of the proposed method is 55.71% and 56.45% lower than that of the terminal sliding mode fixed-time controller without output constraints in Case 1 and Case 2 respectively, and it can ensure that the outputs of the USR system are strictly limited within the preset safety boundary, indicating the superiority of the tracking performance of the designed control method.

Key words: safety constraint, uncertain space robot(USR), second-order sliding mode, fixed time, emergency control, output constraint

CLC Number:

X941

LEI Ronghua, HOU Hailiang, FU Xiaodong. Global fixed-time emergency control of space robot under safety constraints[J]. China Safety Science Journal, 2025, 35(12): 103-110.

Figures/Tables 8

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Table 1

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控制方法	RMSE(算例1)	RMSE(算例2)
GFEC	5.047 1×10^-5	1.358 3×10^-4
DNNC	3.825 8×10^-4	3.655 4×10^-4
TSMFTC	1.139 6×10^-4	3.118 6×10^-4