This article presents an adaptive integral backstepping sliding mode controller (AIBSC) for a class of microgravity electromagnetic vibration isolation systems (MEVIS) that exhibit nonlinearity and uncertainty. To address the errors caused by the backstepping strategy, a finite-time command filter is applied. Additionally, to overcome acceleration disturbances, a fixed-time observer is used for estimation. Lyapunov theory is employed to prove the global asymptotic stability of the proposed controllers. Finally, simulations demonstrate that this controller ensures system stability while improving the isolation performance.

A fixed-time sliding mode controller is developed for the three-degree-of-freedom air-floating robot (AFR) in the presence of model uncertainties and external disturbances. By dynamics transformation, the complex nonlinear AFR dynamics are transformed into a second-order feedback decoupling model. A neural network enhanced by actor–critic learning structure is designed to handle model uncertainties, and the nonsingular fast terminal sliding mode controller can ensure all signals in the closed-loop system converge to a residual set around the origin within a fixed time. The system stability is proved by Lyapunov theory and the simulation results show the effectiveness of the proposed scheme.

Aiming at the problem of residual moment generated by the motion of spacecraft active loads, an improved method for measuring and calibrating it is proposed, and an on-ground residual moment measurement and calibration system based on the combination of three-dimensional force sensors and a three-axis air bearing testbed is presented for this method. The composition and working principle of the system is studied, the fixed relationship between the three-dimensional force sensors and the three-axis air bearing testbed is given, and the algorithm for measuring the residual moment of active loads is proposed. According to the algorithm, the effects of the installation error, measurement error, and measurement disturbance of the three-dimensional force sensors on the residual moment measurement accuracy are given, and the mapping relationship from different ranges and different installation errors to measurement errors of three-dimensional force sensors is studied. Theoretical and simulation analysis shows that the measurement errors of the residual moment are 0.059%, 0.064%, and 0.054%. The method is less affected by environmental interference and restrictions, with high measurement accuracy and excellent applicability.

This paper proposes a spacecraft dynamics full-physical simulator based on air bearing technology, which can effectively simulate the micro-damping dynamic environment of spacecraft in outer space. This paper gives the kinematics model and dynamic equations of the simulator, and analyzes the similarity of the attitude dynamics between the simulator and the real spacecraft. Referring to the real on-orbit spacecraft, the simulator selects the reaction flywheel and the gas injection system as the actuators, designs a control switching algorithm, and uses data fusion technology to switch the mode of the attitude measurement system. Finally, an attitude control simulation test is carried out. The test results verify the correctness and feasibility of the simulator. Using the full- physical simulator proposed in this paper, we not only can carry out spacecraft dynamics experiments on the ground, but also can verify various algorithms, which has important engineering application value.

This paper investigates the fuzzy H∞filter design issue for nonlinear systems with time-varying delay. In order to obtain less conservative fuzzy H∞filter design method, a novel integral inequality is employed to replace the conventional Lebniz-Newton formula to analyze the stability conditions of the filtering error system. Besides, the information of the membership functions is introduced in the criterion to further relax the derived results. The proposed delay dependent filter design method is presented as LMI-based conditions, and corresponding definite expressions of fuzzy H∞filter are given as well. Finally, a simulation example is provided to prove the effectiveness and superiority of the designed fuzzy H∞filter.

The stability analysis and control design problem of Takagi-Sugeno (T-S) fuzzy time-delay systems under mismached premise membership functions are investigated in this paper. A membership function dependent stability criterion is derived first based on Lyapunov stability analysis method. As the information of the membership functions is included in the derived criterion, it is less conservtive than those of independent ones. Then, a fuzzy controller is derived to stabilize the corresponding closed-loop system. All the conditions in this paper are described in linear matrix inequalities (LMIs) frame that can be handled numerically. Finally, some numerical examples are presented to indicate the effectiveness of our approach.