Satellites are subject to complex loads during launch, and harsh vibration environments often result in failures in launching satellites or damage to on-board instruments. A six-degree-offreedom conical vibration isolation platform with magnetorheological dampers has been proposed, which is highly integrated and used to partially replace the original connection device to improve the vibration environment. A mathematical model of the vibration isolation platform with rigid payload is established and natural frequencies are solved. On the other hand, a dynamic model of the vibration isolation system including the flexible satellite is established by using dynamic software, and modal analysis and vibration analysis are carried out. The first six natural frequencies of the system obtained by simulation are close to the results of the model solution. Finally, the test platform is built and the ground vibration tests are conducted, and a well-known semi-active control approach called Skyhook is implemented. The test results are in good agreement with the simulation results of the vibration analysis, and the designed vibration isolation system has much better vibration isolation performance than the original system.
Whole-satellite vibration isolation system with magneto-rheological (MR) damper is a new idea to solve the problem of small amplitude and medium-high frequency vibration. However, it also brings challenges to MR technology, wherein the super hysteresis and variable stiffness properties of MR damper are lack of research. Considering the particularity of MR damper under small amplitude and medium-high frequency conditions, the MR damper is identified by employing an improved Bingham model, then dynamic characteristics of the whole-satellite system are analyzed by nonlinear bifurcation theory, and then the nonlinear analysis method of MR whole-satellite system with variable parameters is proposed. To verify the effectiveness of the nonlinear analysis method of MR whole-satellite system with variable parameters, the influence of bifurcation parameters on the system parameters is analyzed qualitatively and quantitatively, then time histories and phase diagrams of fixed-parameter and parameter-varying MR whole-satellite system are compared. The analysis suggests that the improved Bingham model adequately characterizes the strong nonlinear hysteretic and variable stiffness behavior of the MR damper. Moreover, the comparison results illustrate that the time histories and phase portraits of the parameter-varying system are in good agreement with those of different fixed-parameter system, and the parameter-varying system has good adaptability in the selected range of bifurcation parameters. This study provides a basis for the design of structural parameters and the optimization of control strategy for MR whole-satellite system.
The satellite carried by the launch vehicle is subject to complex loads in the launch process, which can easily lead to the failure of the satellite launching. To improve the response of an existing magnetorheological (MR) whole-satellite system under small amplitude and medium-high frequency vibration during the launch phase, the MR damper is redesigned, and the controllability of the improved system is analyzed, and then a human-simulated intelligent controller (HSIC) is designed. After analyzing the over-damping problem of the existing MR whole-satellite system through sinusoidal sweep and impact simulation tests, the MR damper is redesigned and tested, then the controllability of the improved system is analyzed using vibration theory. Based on the theory of the HSIC, the feature model, control rules, and control modes of the intelligent controller are designed, and the controller parameters are optimized by genetic algorithm. The system simulation model based on HSIC is built to simulate the vibration control of the system. The simulation results show that compared with the skyhook control, the HSIC control method can not only effectively reduce the satellite resonance peak, but also has an obvious vibration reduction at a specific frequency band (40 Hz), which verifies the effectiveness of the algorithm.
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