共查询到20条相似文献,搜索用时 15 毫秒
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Multibody dynamics and robust control of flexible spacecraft 总被引:1,自引:0,他引:1
The paper focuses on an approach to the study of the dynamics and control of large flexible space structures, comprised of subassemblies, a subject of considerable contemporary interest. To begin with, a relatively general Lagrangian formulation of the problem is presented. The governing equations are nonlinear, nonautonomous, coupled, and extremely lengthy even in matrix notation. Next, an efficient computer code is developed and the versatility of the program illustrated through a dynamical study of the first element launch (FEL) configuration of the Space Station Freedom, now superseded by the International Space Station. Finally, robust control of the rigid body motion of the FEL configuration using both the linear-quadratic-Gaussian/loop transfer recovery (LQG/LTR) and H∞ procedures is demonstrated. The controllers designed using the simplified linear models, prove to be effective in regulating librational disturbances. Such a global approach-formulation numerical code, dynamics, and control-is indeed rare. It can serve as a powerful tool to gain comprehensive understanding of dynamical interactions and thus aid in the development of an effective and efficient control system 相似文献
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Ming-Tsan Lin Tian-Hua Liu 《IEEE transactions on aerospace and electronic systems》2001,37(4):1344-1358
A robust controller design for a synchronous reluctance drive system is presented. Based on a simplified model of the system, a robust position controller has been derived. A digital signal processor (DSP), TNO-320-C30, is used to implement the control algorithm. Furthermore, all the current, velocity, and position control loops are executed by the DSP. The system, as a result, is very flexible. Although the hardware circuit of the system is very simple, the synchronous reluctance drive system can accurately control a one-axis table. In addition, the system also has good transient response, load disturbance response, and tracking ability. Several experimental results validate the theoretical analysis 相似文献
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The author presents a high-sensitivity signal processing approach for detecting and estimating the angle of arrival (AOA), frequency and pulse repetition frequency (PRF) of multiple radar emitters using broadband interferometers. Two time series are generated using information embedded in the sampled cross correlation of the signals obtained from three antenna elements (i.e. two base legs). The phase and amplitude of a complex Fourier transform of these two time series with respect to the sampling clock are used to estimate the AOA and PRF of pulsed emitters 相似文献
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鲁棒成形极化敏感阵列波束的方法及极化估计 总被引:1,自引:0,他引:1
基于极化敏感阵列,提出了一种鲁棒成形阵列波束的方法。该方法首先将阵列的数据模型进行了重新描述,从而获得了信号波达角(DOA)和极化解耦的模型。借助于该模型并对信号的两个极化方向分别进行鲁棒约束,设计出了一个新的鲁棒空域波束空间成形矩阵,利用该矩阵可以获得信号两个极化分量的鲁棒估计。基于特征值分解的方法,最后给出了估计信号极化参数的方法。分析和数值仿真实验均表明:提出的方法,在对DOA估计误差以及阵列位置误差等造成的阵列失配具有较强鲁棒性的同时,也能有效抑制干扰和噪声,进而提升了极化参数估计的性能。 相似文献
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Two methods for constructing robust polarimetric constant-false-alarm-rate (CFAR) detectors that use elements of the scattering matrix are discussed. Both methods use robust estimators to recognize outliers and exclude them from further calculations. The first method weighs each sample of the surrounding vectors, and vectors that appear to be outliers are weighted with lower values than the others. The second method uses cluster algorithms to arrange the data in different clusters; some clusters contain the outliers, and others contain observations assumed to come from the main body of the data. The detectors are intended to be used in multitarget and nonhomogeneous-clutter environments 相似文献
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The article focuses on the design and application of an active reconfigurable controller that mitigates the effects of gust load and actuator faults on a flexible aircraft. A novel integrated adaptive output feedback scheme is investigated to address the actuator faults. The real-time fault values provided by the fault estimation module are considered in the reconfigurable control law to improve the fault-tolerant capability. The estimate values of faults and control gains are calculated by anal... 相似文献
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针对某型涡扇发动机,分析了H∞,H∞/H2和u控制存在的不足,提出了一种基于Homotopy算法发动机固定阶控制设计方法。采用规范形式控制器结构进行固定阶H∞/H2控制器设计,推导出了固定阶H∞/H2控制器存在的必要条件,使用Homotopy算法获得最优固定阶H∞/H2控制器的解。提出了将固定阶H∞/H2控制器与混合u综合相结合获得固定阶混合u控制器的策略。与全阶混合u控制器不同,固定阶混合u控制器具有结构简单,易于实现,而其鲁棒性能和鲁棒稳定性与全阶u控制器相近。使用该方法对某型涡扇发动机控制系统进行固定阶混合u控制器设计,仿真验证表明,该控制系统其性能鲁棒性满足要求。 相似文献
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A digital beamforming processor for an adaptive array radar is described. The functionality and the architecture of the processor are strongly driven by a goal of achieving adaptive null depths in the 60-dB to 70-dB range, which necessitates substantial preprocessing of each channel. In particular, conversion to baseband quadrature channels is accomplished digitally using a single A/D converter per channel, and FIR (finite impulse response) equalizing filters are employed in each channel to match channel transfer functions. The processor is highly modular, and this not only distributes the total processing load, but also the I/O (input/output) bandwidth requirement. This is accomplished by distributing the adaptive beamforming algorithm systolically across a linear array of processing nodes. The processor is expandable to a different number of channels and sufficiently flexible to be applied to other problems of an array signal processing nature. Experimental data presented demonstrate that the processor is capable of supporting channel-to-channel cancellation of interfering signals to the level of -65 dB 相似文献
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A method for simulating a flexible spacecraft motion using Lagrange’s quasivelocity formulation is considered. An algorithm
of quasivelocity formation by Walsh’s means is proposed. This method can be used to evaluate a quasistatic microacceleration
field component in the spacecraft internal environment. 相似文献
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以涡扇发动机模拟低压转子为研究对象,探究了模拟低压转子在动力特性试验过程中出现的非整数倍频振动超限的原因,提出了涡轮结构改进措施。对比分析了结构改进前后模拟低压转子的前三阶临界转速及其裕度。完成了全转速范围内的动力特性试验,验证了改进措施的有效性,排除了振动故障。研究表明,涡轮结构改进措施有效,临界转速计算误差小于4%,与试验结果具有较好的一致性。研究结果为真实低压转子动力学设计和结构设计提供了参考。 相似文献
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Anastassopoulos V. Lampropoulos G. 《IEEE transactions on aerospace and electronic systems》1992,28(2):420-427
A constant false alarm rate (CFAR) detection method which is based on a combination of median and morphological filters (MEMO) is proposed. The MEMO algorithm has robust performance with small CFAR loss, very good behavior at clutter edges and high detection performance in the case of closely spaced narrowband signals (targets). The proposed MEMO method is favourably compared with cell averaging (CA) and ordered statistics (OS) CFAR detectors. The Monte Carlo method is employed to analyze the MEMO-CFAR detector 相似文献
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An efficient method employing a Principal Component Analysis(PCA)-Deep Belief Network(DBN)-based surrogate model is developed for robust aerodynamic design optimization in this study. In order to reduce the number of design variables for aerodynamic optimizations, the PCA technique is implemented to the geometric parameters obtained by parameterization method.For the purpose of predicting aerodynamic parameters, the DBN model is established with the reduced design variables as input and the aero... 相似文献
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In this research a two-motion medium-aspect-ratio straight flexible wing model was tested. Tests with the wing model were conducted in the subsonic wind tunnel of the Faculty of Aerospace Engineering at the Technion, Israel. Experimental results obtained for flutter and Limit Cycle Oscillations (LCO) of the wing model are presented. At least two types of flutter and postflutter LCO have been observed. Both types were characterized by coupling between the torsional and bending modes. The first type flutter was associated with coupling of the first bending and first torsional modes, whereas the second type was observed for coupling of the first torsional and second bending modes. 相似文献
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《中国航空学报》2021,34(3):164-175
In this paper, a robust adaptive controller is designed for a guided spinning rocket, whose dynamics presents the characteristics of pitch-yaw cross coupling, fast time-varying aerodynamics parameters and wide flight envelop. First, a coupled nonlinear six-degree-of-freedom equation of motion for a guided spinning rocket is developed, and the lateral acceleration motion is modeled as a control plant with time-varying matched uncertainties and unmodeled dynamics. Then, a robust adaptive control method is proposed by combining Bregman divergence and variational method to achieve fast adaption and maintain bounded tracking. The stability of the resulting closed-loop system is proved, and the ultimate bound and convergence rate are also analyzed. Finally, numerical simulations are performed for a single operating point and the whole flight trajectory to show the robustness and adaptability of the proposed method with respect to time-varying uncertainties and unmodeled dynamics. 相似文献
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Optimal robust linearized impulsive rendezvous 总被引:3,自引:1,他引:2
The optimization of time-fixed linearized impulsive rendezvous with control uncertainty is investigated. One performance index related to the variances of the terminal state error is defined as the performance index of robustness which is calculated by linear covariance method. The two-objective optimization problem of minimizing the total characteristic velocity and the performance index of robustness is formulated based on the Clohessy–Wiltshire (C-W) system and solved by the nondominated sorting genetic algorithm. The Pareto-optimal solution sets of one homing rendezvous mission are provided and the Pareto optimality is verified by comparing with the fuel-optimal and the robustness-optimal solutions. It is shown that the proposed approach can quickly investigate the relation between the fuel cost and the trajectory robustness, besides evaluate different rendezvous maneuver schemes. 相似文献