VFAS辐射角系数自适应软件系统

VFAS 软件系统是以原角系数程序VF01、VF02为基础,采用了新的数学方法,改变表面之间的角系数计算为结点之间的角系数计算,解决了辐射干扰结点的自动判断,将人工划分与组合的大量繁杂工作全部由软件系统完成,大大减轻了工程设计人员的工作量,且使计算精度得到根本改善。     

Adaptive finite-time backstepping control for attitude tracking of spacecraft based on rotation matrix

This paper investigates two finite-time controllers for attitude control of spacecraft based on rotation matrix by an adaptive backstepping method. Rotation matrix can overcome the draw- backs of unwinding which makes a spacecraft perform a large-angle maneuver when a small-angle maneuver in the opposite rotational direction is sufficient to achieve the objective, With the use of adaptive control, the first robust finite-time controller is continuous without a chattering phenom- enon. The second robust finite-time controller can compensate external disturbances with unknown bounds. Theoretical analysis shows that both controllers can make a spacecraft following a time-varying reference attitude signal in finite time and guarantee the stability of the overall closed-loop system. Numerical simulations are presented to demonstrate the effectiveness of the proposed control schemes.     

空间机器人柔性关节轨迹控制研究

针对由谐波减速器驱动的空间机器人柔性关节的精确轨迹跟踪问题,提出了一种由自 适应模糊系统和逐步逆向设计相结合的递阶控制方法,不仅有效地消除了模型不确定性的 影 响,而且避免了复杂的求导运算和角加速度可测的要求;推导了自适应模糊系统模糊规则参 数调整的自适应律,证明了闭环系统的稳定性和跟踪误差的渐进收敛;在柔性关节测试平台 上进行了轨迹跟踪实验,试验结果表明该方法具有较高的轨迹控制精度和鲁棒性。     

Mesh deformation on 3D complex configurations using multistep radial basis functions interpolation

The Radial Basis Function (RBF) method with data reduction is an effective way to perform mesh deformation. However, for large deformations on meshes of complex aerodynamic configurations, the efficiency of the RBF mesh deformation method still needs to be further improved to fulfill the demand of practical application. To achieve this goal, a multistep RBF method based on a multilevel subspace RBF algorithm is presented to further improve the efficiency of the mesh deformation method in this research. A whole deformation is divided into a series of steps, and the supporting radius is adjusted in accordance with the maximal displacement error. Furthermore, parallel computing is applied to the interpolation to enhance the efficiency. Typical deformation problems of the NASA Common Research Model (CRM) configuration, the DLR-F6 wing-body-nacelle-pylon configuration, and the DLR-F11 high-lift configuration are tested to verify the feasibility of this method. Test results show that the presented multistep RBF mesh deformation method is efficient and robust in dealing with large deformation problems over complex geometries.     

Error constrained control of a pseudo-satellite with disturbance

This paper presents the control scheme of a pseudo-satellite in situations where error constraints, uncertainties, and external disturbances occur. The control scheme of a pseudo-satellite includes planar path following control scheme and altitude control scheme. In order to control the altitude of a pseudo-satellite, the backstepping technique is used to control the quality of air in the air balloon. To deal with the error constrained requirements of a pseudo-satellite’s position, a tan-type barrier Lyapunov function (TBLF) is proposed and incorporated with the guidance control schemes. Adaptive fuzzy disturbance observers are presented to estimate uncertainties and external disturbances. Rigorous stability analysis proves that the altitude error of the pseudo-satellite can be uniformly bounded, and the position error of which can be maintained within the range of constrained requirements, while all closed-loop signals are uniformly bounded regardless of uncertainties and disturbances.     

Pressure distribution feature-oriented sampling for statistical analysis of supercritical airfoil aerodynamics

In the field of supercritical wing design, various principles and rules have been summarized through theoretical and experimental analyses. Compared with black-box relationships between geometry parameters and performances, quantitative physical laws about pressure distributions and performances are clearer and more beneficial to designers. With the advancement of computational fluid dynamics and computational intelligence, discovering new rules through statistical analysis on computers has beco...     

空间飞行器抓捕非合作目标后的复合控制

随着空间技术的不断发展，空间飞行器抓取非合作目标的稳定控制技术变得日益重要。基于拉格朗日动力学原则对空间飞行器进行动力学建模，考虑了非合作目标的未知参数、空间飞行器模型的不确定性及存在外部干扰的情况，理论分析了自适应控制及基于非线性干扰观测控制的可行性，并对比了二者的优缺点。在此基础上提出了一种可以在线精确估计非合作目标未知参数的复合控制方法，并进行了仿真验证。仿真结果表明，所提方法能够将所有参数的估计误差限制在很小的范围内，相对于自适应控制方法有了显著改善。     

自适应预测补偿的迭代制导方法及其应用研究

针对迭代制导完成后入轨参数或终端程序角修正问题,研究一种基于模型参考的自适应预测补偿迭代制导算法在运载火箭上的应用。该算法在经典迭代制导算法的基础上,根据预测的迭代终端程序角和飞行视加速度的参考模型,对关机点参数进行补偿,依据补偿后的终端指标重新规划飞行轨迹,进而得出满足入轨参数或终端程序角偏差修正的制导指令,提升迭代制导对入轨参数偏差或终端程序角的修正能力。此外,阐述了经典迭代制导的基本算法,概括了自适应预测补偿迭代制导算法的基本原理,并以大推力直接入轨、终端程序角大偏差以及满足终端程序角约束为例,给出相应工况的自适应预测补偿的迭代制导算法。仿真结果表明：该算法对入轨参数和终端程序角偏差具有一定的修正能力。     

一种高超声速试飞器助推段主动弹性抑制方法

针对高超声速试飞器助推段由于其高静不稳定特性所引起的低频弹性模态与刚体高带宽控制之间动态耦合问题,具有低频模态和大静不稳定度等特征,引入主动弹性抑制技术,即在传统控制器的设计基础上引入弹性振动能量在线辨识技术相结合的改进自适应增广控制技术(Adaptive augmenting control, AAC),动态改变开环系统控制增益,以降低弹性模态对舵机的影响,同时增加刚体控制系统的稳定性。仿真结果验证了该方法能够有效减小由干扰激励出的弹性模态所引起的附加舵机摆角,抑制伺服弹性耦合作用。该方法对高超声速试飞器助推段的控制具有重要的理论意义和工程应用价值。     

一个解析三维非结构网格生成方法

给出了一个三维非结构网格生成方法。提出弱区域指示函数描述三维封闭流场形状,并证明了该函数的存在不唯一性。利用该函数基于Delaunay方法依据流场尺度生成网格结构。其中,边界引力有效解决了流场边界恢复和内嵌边界问题,弹簧振子和正四面体趋进技术有效调整网格结构并提高网格质量。最后,弹簧振子和边界引力随着弱区域指示函数的演变与监测函数的指导成功应用到自适应网格生成。