Adaptive path planning for unmanned aerial vehicles based on bi-level programming and variable planning time interval

This paper presents an adaptive path planner for unmanned aerial vehicles (UAVs) to adapt a real-time path search procedure to variations and fluctuations of UAVs’ relevant performances, with respect to sensory capability, maneuverability, and flight velocity limit. On the basis of a novel adaptability-involved problem statement, bi-level programming (BLP) and variable planning step techniques are introduced to model the necessary path planning components and then an adaptive path planner is developed for the purpose of adaptation and optimization. Additionally, both probabilistic-risk-based obstacle avoidance and performance limits are described as path search constraints to guarantee path safety and navigability. A discrete-search-based path planning solution, embedded with four optimization strategies, is especially designed for the planner to efficiently generate optimal flight paths in complex operational spaces, within which different surface-to-air missiles (SAMs) are deployed. Simulation results in challenging and stochastic scenarios firstly demonstrate the effectiveness and efficiency of the proposed planner, and then verify its great adaptability and relative stability when planning optimal paths for a UAV with changing or fluctuating performances.     

柔性转子逆回旋振动特性的研究

论述了具有陀螺效应的柔性转子在各向异性支承条件下回旋振动的特性，推导出了转子在正回旋激励作用下产生逆回旋振动的条件，提出转子振动存在逆回旋带的概念，并举例说明了转子在整个转速范围和振动频率范围内回旋振动的特点，作出了逆回旋带的曲线图。     

空间目标高分辨距离像运动参数估计

建立了宽带线性调频雷达信号的空间目标回波模型，对目标回波信号进行了分析，分析了空间目标高速运动对目标高分辨一维距离像的影响，提出了用多项式变换进行参数估计的方法。利用估计参数进行运动补偿，消除目标速度和加速度对目标一维距离像的影响。最后给出了仿真结果，验证了本文的分析结果正确和算法有效。     

物—伞系统运动稳定性初探

弹道－升力式再入飞行器常采用旋成体外形，但其质心偏离对称轴（纵轴）设置。这种飞行器在着陆前要采用降落伞作为主减速手段。研究质心偏离对称轴的旋成体与降落伞组成的系统的运动稳定性是一项有工程实践意义的课题。作为一种初步探索，在把降落伞视作刚体的条件下，按该系统平面运动方程考察其在平衡状态附近的稳定性，给出了运动稳定性判据。     

多个自由飞行空间机器人协调操作运动规划

本文提出了在空间微重力环境下多个自由飞行空间机器人协调操作运动规划算法，首先推导出多个自由飞行空间机器人协调操作的广义雅可比矩阵，其次给出了基于该矩阵的多个自由飞行空间机器人协调操作分解运动速度控制算法，最后用计算机仿真验证了该算法的正确性。     

Motion prediction of a non-cooperative space target

Capturing a non-cooperative space target is a tremendously challenging research topic. Effective acquisition of motion information of the space target is the premise to realize target capture. In this paper, motion prediction of a free-floating non-cooperative target in space is studied and a motion prediction algorithm is proposed. In order to predict the motion of the free-floating non-cooperative target, dynamic parameters of the target must be firstly identified (estimated), such as inertia, angular momentum and kinetic energy and so on; then the predicted motion of the target can be acquired by substituting these identified parameters into the Euler’s equations of the target. Accurate prediction needs precise identification. This paper presents an effective method to identify these dynamic parameters of a free-floating non-cooperative target. This method is based on two steps, (1) the rough estimation of the parameters is computed using the motion observation data to the target, and (2) the best estimation of the parameters is found by an optimization method. In the optimization problem, the objective function is based on the difference between the observed and the predicted motion, and the interior-point method (IPM) is chosen as the optimization algorithm, which starts at the rough estimate obtained in the first step and finds a global minimum to the objective function with the guidance of objective function’s gradient. So the speed of IPM searching for the global minimum is fast, and an accurate identification can be obtained in time. The numerical results show that the proposed motion prediction algorithm is able to predict the motion of the target.     

航天器分裂体或抛射物的轨道形成和演化

由卫星和碎片爆炸或相互间碰撞所产生的分裂体,或由在轨航天器向外抛射所产生的抛射物,对空间环境的影响正日益增大。对它们轨道形成和演化的研究可以为分析空间解体事件提供一种有效方法。本文利用Kep-ler运动积分以及受摄二体问题的分析解,建立了分裂体或抛射物的轨道形成及其演化与分裂或抛射速度之间的关系,从而为理解以各个方向、不同大小的速度分裂或抛射的物体的轨道演化特征提供理论依据。文章最后通过数值验证表明了该方法的有效性。     

Real-time trajectory planning for UCAV air-to-surface attack using inverse dynamics optimization method and receding horizon control

This paper presents a computationally efficient real-time trajectory planning framework for typical unmanned combat aerial vehicle (UCAV) performing autonomous air-to-surface (A/S) attack. It combines the benefits of inverse dynamics optimization method and receding horizon optimal control technique. Firstly, the ground attack trajectory planning problem is mathematically formulated as a receding horizon optimal control problem (RHC-OCP). In particular, an approximate elliptic launch acceptable region (LAR) model is proposed to model the critical weapon delivery constraints. Secondly, a planning algorithm based on inverse dynamics optimization, which has high computational efficiency and good convergence properties, is developed to solve the RHCOCP in real-time. Thirdly, in order to improve robustness and adaptivity in a dynamic and uncer- tain environment, a two-degree-of-freedom (2-DOF) receding horizon control architecture is introduced and a regular real-time update strategy is proposed as well, and the real-time feedback can be achieved and the not-converged situations can be handled. Finally, numerical simulations demon- strate the efficiency of this framework, and the results also show that the presented technique is well suited for real-time implementation in dynamic and uncertain environment.     

Z-pin自动植入数控系统研制及性能研究

为实现Z-pin的数控自动植入,以可编程多轴控制器PMAC作为运动控制的核心、附卡控制辅助开关量,设计了基于开放式数控系统的X-cor芯材成型专用CNC硬件体系。试制了多种规格的X-cor夹层结构试样,分别研究了Pin直径、Pin植入角以及Pin分布密度等参数对X-cor夹层结构压缩性能、剪切性能的影响。结果表明,Pin可以大幅度提高X-cor夹层结构的压缩性能,同时提高了断裂韧性。     

基于凌阳16位单片机SPCE061A悬挂运动控制系统

以凌阳16位单片机SPCE061A为控制核心，通过所需运动轨迹曲线的参数方程建立运动控制模型，按照算法对两组驱动步进电机进行控制，实现了悬挂画笔在给定的范围内的定点运动、任意曲线运动以及圆心可任意设定的圆周运动等功能，不仅完成了要求发挥的部分功能，同时还增加了语音播放功能。