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241.
Robust H∞ controller design for attitude stabilization of flexible spacecraft with input constraints
Chuang Liu Keke Shi Zhaowei Sun 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(5):1498-1522
This paper addresses the attitude stabilization and vibration suppression problem for flexible spacecraft subject to model parameter uncertainty, controller perturbations, external disturbances and input constraints. The attitude model of flexible spacecraft is described and converted into a state space form in terms of passive and active vibration suppression schemes. A novel state feedback controller is proposed based on the exactly available expectation of a new variable, which is introduced to model a randomly occurring controller gain perturbation. Based on Lyapunov stability theory, sufficient conditions for the existence of the nonfragile H∞ controller considering input constraints are given based on linear matrix inequalities (LMIs) in terms of additive perturbation and multiplicative perturbation. Then, the developed controller subject to required constraints can be obtained, where the nonfragile property is fully considered to improve the tolerance to uncertainties in the controller. Numerical simulations are performed to demonstrate the effectiveness and superiority of the proposed control strategy in attitude stabilization and vibration suppression, where it should be noted that the passive vibration suppression scheme is superior for high natural frequencies while the active vibration suppression scheme is superior for low natural frequencies. Moreover, the low natural frequencies have more influence on the performance of attitude stabilization and vibration suppression. 相似文献
242.
The tracking control problem for Flexible Joint Manipulator Control System(FJMCS)with unmeasurable states is addressed in this paper. Firstly, a High-Gain Observer(HGO) is constructed to estimate the unmeasurable states and the uncertainties. Then, a Dynamic Surface Control(DSC) scheme is developed by using the estimation of HGO. The newly proposed controller has two advantages over the existing methods:(A) a novel Spike Suppression Function(SSF) is developed to avoid the estimation spike proble... 相似文献
243.
《中国航空学报》2020,33(10):2679-2693
In recent years, the Active Flutter Suppression (AFS) employing Linear Parameter-Varying (LPV) framework has become a hot spot in the research field. Nevertheless, the flutter suppression technique is facing two severe challenges. On the one hand, due to the fatal risk of flight test near critical airspeed, it is hard to obtain the accurate mathematical model of the aeroelastic system from the testing data. On the other hand, saturation of the actuator may degrade the closed-loop performance, which was often neglected in the past work. To tackle these two problems, a new active controller design procedure is proposed to suppress flutter in this paper. Firstly, with the aid of LPV model order reduction method and State-space Model Interpolation of Local Estimates (SMILE) technique, a set of high-fidelity Linear Time-Invariant (LTI) models which are usually derived from flight tests at different subcritical airspeeds are reduced and interpolated to construct an LPV model of an aeroelastic system. And then, the unstable aeroelastic dynamics beyond critical airspeed are ‘predicted’ by extrapolating the resulting LPV model. Secondly, based on the control-oriented LPV model, an AFS controller in LPV framework which is composed of a nominal LPV controller and an LPV anti-windup compensator is designed to suppress the aeroelastic vibration and overcome the performance degradation caused by actuator saturation. Although the nominal LPV controller may have superior performance in linear simulation in which the saturation effect is ignored, the results of the numerical simulations show that the nominal LPV controller fails to suppress the Body Freedom Flutter (BFF) when encountering the actuator saturation. However, the LPV anti-windup compensator not only enhances the nominal controller’s performance but also helps the nominal controller to stabilize the unstable aeroelastic system when encountering serious actuator saturation. 相似文献
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提升合成孔径雷达(SAR)图像质量以增强其可判读性,一直是SAR图像处理中的关键问题。近年来,深度学习在光学图像处理中取得显著的成功,并逐步应用到SAR图像质量提升领域。对深度学习在SAR图像质量提升中的关键应用进行综述,对深度学习在SAR图像质量提升中采用的典型网络进行了介绍,并从SAR图像旁瓣抑制、超分辨(SR)处理和图像融合3个方面对深度学习的应用进行阐述。最后,分析与探讨了基于深度学习的SAR图像质量提升中的关键问题及进一步研究方向。 相似文献
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电容器涌入电流的抑制,是TSC式消弧线圈设计中要考虑的一个重要问题。文章对TSC式消弧线圈的工作原理和运行特点进行了分析,对电容器投入电网运行时的涌入电流分两种情况进行了研究,得出了TSC式消弧线圈涌入电流的计算方法。最后给出抑制涌流的两种方法—零压差投入和串联扼流线圈。 相似文献