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331.
332.
双CPU环境下飞行控制软件的设计 总被引:2,自引:1,他引:1
本文介绍运载火箭飞行控制软件在双CPU冗余硬件配置下的可靠性设计和可靠性指标分配的方法。文中提到的部分技术经过了实验的检验,证明是可行的 相似文献
333.
同伦方法中辅助映射的影响 总被引:1,自引:0,他引:1
简述了同伦方法中解曲线跟踪算法,它是求解非线性问题的一种非常有效的方法,并说明辅助映射的构造形式将影响非线性问题的求解。根据同伦方法的基本思想和求解过程,提出了采用“相似”准则设计辅助映射的方法,即辅助映射要与原映射同类型,使待求函数较为容易地同化变形到辅助映射,同时求到问题的解。该方法已应用于一些实际课题中。效果很好。 相似文献
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335.
The continuous growth of air traffic has led to acute airspace congestion and severe delays, which threatens operation safety and cause enormous economic loss. Flight assignment is an economical and effective strategic plan to reduce the flight delay and airspace congestion by reasonably regulating the air traffic flow of China. However, it is a large-scale combinatorial optimization problem which is difficult to solve. In order to improve the quality of solutions, an effective multi-objective parallel evolution algorithm(MPEA) framework with dynamic migration interval strategy is presented in this work. Firstly, multiple evolution populations are constructed to solve the problem simultaneously to enhance the optimization capability. Then a new strategy is proposed to dynamically change the migration interval among different evolution populations to improve the efficiency of the cooperation of populations. Finally, the cooperative co-evolution(CC) algorithm combined with non-dominated sorting genetic algorithm II(NSGA-II) is introduced for each population. Empirical studies using the real air traffic data of the Chinese air route network and daily flight plans show that our method outperforms the existing approaches, multiobjective genetic algorithm(MOGA), multi-objective evolutionary algorithm based on decomposition(MOEA/D), CC-based multi-objective algorithm(CCMA) as well as other two MPEAs with different migration interval strategies. 相似文献
336.
Dynamics modeling and control of a transport aircraft for ultra-low altitude airdrop 总被引:1,自引:0,他引:1
The nonlinear aircraft model with heavy cargo moving inside is derived by using the separation body method, which can describe the influence of the moving cargo on the aircraft attitude and altitude accurately. Furthermore, the nonlinear system is decoupled and linearized through the input–output feedback linearization method. On this basis, an iterative quasi-sliding mode(SM)flight controller for speed and pitch angle control is proposed. At the first-level SM, a global dynamic switching function is introduced thus eliminating the reaching phase of the sliding motion.At the second-level SM, a nonlinear function with the property of ‘‘smaller errors correspond to bigger gains and bigger errors correspond to saturated gains' ' is designed to form an integral sliding manifold, and the overcompensation of the integral term to big errors is weakened. Lyapunovbased analysis shows that the controller with strong robustness can reject both constant and time-varying model uncertainties. The performance of the proposed control strategy is verified in a maximum load airdrop mission. 相似文献
337.
首先根据飞行轨迹稳定性的数学模型,得出了飞机在闭环条件下扰动过程速度的变化规律及飞行轨迹稳定性的应用条件,并且结合不同类型的飞机进行了对比分析。然后以推力曲线为基础分析了不同类型飞机的临速度范围,并根据飞机级曲线对飞行轨迹稳定性界状态与有利速度的关系进行了分析。 相似文献
338.
lhan Tuzcu 《Aerospace Science and Technology》2008,12(5):376-384
The problem of aircraft stability has been a subject of concern since the beginnings of flight. Traditionally, aircraft stability has been treated within the confines of two separate disciplines, namely, flight dynamics and aeroelasticity. Based on some recent developments in the dynamics and control of flexible aircraft, this investigation uses the system concept to provide a broader approach to aircraft stability in an attempt to bridge the gap between stability as understood in flight dynamics and stability as envisioned in aeroelasticity. To this end, stability is studied in the following four cases: 1) dynamics of whole flexible aircraft using the unified formulation, 2) flight dynamics of quasi-rigid aircraft (aircraft treated as rigid), 3) aeroelasticity of flexible components, such as cantilever wing, cantilever horizontal stabilizer, etc., and 4) aeroelasticity of restrained flexible aircraft (aircraft fixed to a point, hence, having no rigid body degrees of freedom). The paper also presents a method to address the stability of flexible aircraft when the compressibility correction factor is known only at some discrete Mach numbers. 相似文献
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340.
Two freedom linear parameter varying μ synthesis control for flight environment testbed 总被引:2,自引:0,他引:2
To solve the problem of robust servo performance of Flight Environment Testbed(FET)of Altitude Ground Test Facilities(AGTF) over the whole operational envelope, a two-degree-offreedom μ synthesis method based on Linear Parameter Varying(LPV) schematic is proposed, and meanwhile a new structure frame of μ synthesis control on two degrees of freedom with double integral and weighting functions is presented, which constitutes a core support part of the paper. Aimed at the problem of reference command's rapid change, one freedom feed forward is adopted, while another freedom output feedback is used to meet good servo tracking as well as disturbance and noise rejection; furthermore, to overcome the overshoot problem and acquire dynamic tuning,the integral is introduced in inner loop, and another integral controller is used in outer loop in order to guarantee steady errors; additionally, two performance weighting functions are designed to achieve robust specialty and control energy limit considering the uncertainties in system. As the schedule parameters change over large flight envelope, the stability of closed-loop LPV system is proved using Lyapunov inequalities. The simulation results show that the relative tracking errors of temperature and pressure are less than 0.5% with LPV μ synthesis controller. Meanwhile, compared with non-LPV μ synthesis controller in large uncertainty range, the proposed approach in this research can ensure robust servo performance of FET over the whole operational envelope. 相似文献