基于DCNLP法的重复使用运载器再入轨迹设计

介绍了DCNLP法在可重复使用运载器再人段轨迹优化中的应用.首先以可重复使用运载器为对象,以攻角和倾侧角为控制变量,并考虑严格的终端约束和过程约束,建立了以航程最远作为优化目标的最优控制问题模型.然后采用DCNLP法将最优控制问题转化为一般的非线性规划问题,选取各节点上的状态量和控制量作为优化参数.最后应用matlab...     

Dynamic modeling and simulation for the rigid flexible coupling system with a non-tip mass

The rigid flexible coupling system with a mass at non-tip position of the flexible beam is studied in this paper. Using the theory about mechanics problems in a non-inertial coordinate system, the dynamic equations of the rigid flexible coupling system with dynamic stiffening are established. It is clearly elucidated for the first time that, dynamic stiffening is produced by the coupling effect of the centrifugal inertial load distributed on the beam and the transverse vibration deformation of the beam. The modeling approach in this paper successfully solves problems of popular modeling methods nowadays: the derivation process is too complex by using only one dynamic principle; a clearly theoretical mechanism for dynamic stiffening can't be offered. First, the mass at non-tip position is incorporated into the continuous dynamic equations of the system by use of the Dirac function and the Heaviside function. Then, based on the conclusions of orthogonalization about the normal constrained modes, the finite dimensional state space equations suitable for controller design are obtained. The numerical simulation results show that: dynamic stiffening is included in the first-order model established in this paper, which indicates the dynamic responses of the rigid flexible coupling system with large overall motion accurately. The results also show that the mass has a softening effect on the dynamic behavior of the flexible beam, and the effect would be more obvious when the mass has a larger mass, or lies closer to the tip of the beam.     

Dynamic modeling and simulation for the flexible spacecraft with dynamic stiffening

A rigid flexible coupling physical model which can represent a flexible spacecraft is investigated in this paper. By applying the mechanics theory in a non-inertial coordinate system, the rigid flexible coupling dynamic model with dynamic stiffening is established via the subsystem modeling framework. It is clearly elucidated for the first time that, dynamic stiffening is produced by the coupling effect of the centrifugal inertial load distributed on the beam and the transverse vibration deformation of the beam. The modeling approach in this paper successfully avoids problems which are caused by other popular modeling methods nowadays: the derivation process is too complex by using only one dynamic principle; a clearly theoretical explanation for dynamic stiffening can't be provided. First, the continuous dynamic models of the flexible beam and the central rigid body are established via structural dynamics and angular momentum theory respectively. Then, based on the conclusions of orthogonalization about the normal constrained modes, the finite dimensional dynamic model suitable for controller design is obtained. The numerical simulation validations show that: dynamic stiffening is successfully incorporated into the dynamic characteristics of the first-order model established in this paper, which can indicate the dynamic responses of the rigid flexible coupling system with large overall motion accurately, and has a clear modeling mechanism, concise expressions and a good convergence.     

考虑动力刚化的挠性飞行器动力学建模与仿真

文中以挠性飞行器的刚柔耦合物理模型为研究对象,引入非惯性系中的力学问题理论,建立了考虑动力刚化的模型,明确地阐明了动力刚化是一种非惯性系中的力学现象。首先分别应用材料力学和角动量定理建立了两个子系统的连续动力学模型,而后基于正则约束模态的正交化结论,建立了离散动力学模型。数值仿真结果表明,文中建立的一次动力学模型考虑了动力刚化,能够准确预测大角度机动下挠性飞行器的动力学响应,可直接用于控制器设计。