基于诱导航线的多无人机编队飞行控制方法

针对无人机编队飞行控制问题,提出了一种基于诱导航线的协同控制方法,僚机根据当前相对于期望位置的误差和长机的飞行状态生成诱导航线并进行跟踪;针对飞行过程中的突发障碍采用改变编队队形的方法进行规避;针对无人机之间可能出现的碰撞情况,根据无人机到达碰撞点的时间以及位置分别从高度以及航向两方面进行躲避,仿真结果表明:采用此方法无人机能够保持稳定的编队,并同时能够躲避飞行过程中的障碍以及避免飞机之间的碰撞。      

氧化钛纳米管的水热法合成机理研究

采用水热合成方法制备出外径约8nm,壁厚为1nm的纳米管,以TEM,XRD和TG等分析手段对不同工艺条件下获得的产物进行了表征,对它们的热稳定性进行了测试。研究结果表明．纳米管是在NaOH水热处理过程中形成的,而不是在清洗过程中形成的。其形成机理可能是纳米氧化钛颗粒在强碱作用下形成的Na2TiO3片状物经过卷曲而成短纳米管,通过溶解一吸收机理,逐渐长成长纳米管。但清洗溶液的pH值对生成的纳米管的成分和结构有影响,通过控制清洗产物时的溶液的pH值和热处理温度,可以获得组成分别为Na2TiO3,H2TiO3和TiO2的纳米管,且纳米管具有较好的热稳定性,在400℃下热处理后,能保持其纳米管形貌,600℃时．纳米管间有烧结的迹象,至800℃时纳米管完全变为颗粒。     

镀钛金刚石钎焊界面微区结构分析

采用Ag-Cu-Ti合金粉末在加热温度920 ℃保温时间8 min条件下真空钎焊镀钛金刚石,运用X射线衍射仪、扫描电镜、能谱仪综合分析界面微观结构、元素分布特征及新生物相形貌。结果表明,镀钛金刚石镀层并不是单一钛的附着层,而是薄层TiC。钎焊过程中,镀钛金刚石磨粒与Ag-Cu-Ti钎料结合界面出现显微组织分层现象,原镀层与 新生层厚度分别约为0.8 μm和5 μm。新生化合物在镀层表面呈短针状致密生长且有序连成片状,在镀层破损处有长约4 μm,宽约1.5 μm针状物,而在破损边缘处碳化物呈棒状背离镀层侧向生长。原子扩散动力学分析显示镀层晶体结构会限制游离C原子的无规则运动,使得新生TiC均匀分散形核并长大。     

An LMI-based decoupling control for electromagnetic formation flight

Electromagnetic formation flight(EMFF) leverages electromagnetic force to control the relative position of satellites. EMFF offers a promising alternative to traditional propellant-based spacecraft flight formation. This novel strategy is very attractive since it does not consume fuel. Due to the highly coupled nonlinearity of electromagnetic force, it is difficult to individually design a controller for one satellite without considering others, which poses challenges to communications.This paper is devoted to decoupling control of EMFF, including regulations, constraints and controller design. A learning-based adaptive sliding mode decoupling controller is analyzed to illustrate the problem of existing results, and input rate saturation is introduced to guarantee the validity of frequency division technique. Through transformation, the imposed input rate saturation is converted to state and input constraints. A linear matrix inequalities(LMI)-based robust optimal control method can then be used and improved to solve the transformed problem. Simulation results are presented to demonstrate the effectiveness of the proposed decoupling control.     

Connectivity preservation and collision avoidance control for spacecraft formation flying in the presence of multiple obstacles

This paper addresses connectivity preservation and collision avoidance problem of spacecraft formation flying with multiple obstacles and parametric uncertainties under a proximity graph. In the proximity graph, each spacecraft can only get the states of the neighbor spacecraft within its sensing region. Connectivity preservation of a graph means that the connectivity of the graph should be preserved at all times during spacecraft formation flying. We consider two cases: (i) the obstacles are static, and (ii) the obstacles are dynamic. In the first case, a distributed continuous control algorithm based on artificial potential function and equivalent certainty principle is proposed to account for the unknown parameters and the static obstacles. In the second case, a sliding surface combined with a distributed adaptive control algorithm is proposed to tackle the influence of the dynamic obstacles and the unknown parameters at the same time. With the distributed control algorithms, the desired formation configuration can be achieved while the connectivity of the graph is preserved and the collisions between the spacecraft and the obstacles are avoided. Numerical simulations are presented to illustrate the theoretical results.     

舰艇编队网络化反导作战指挥体系研究

网络中心作战条件下,传统作战指挥体系已经无法满足作战指挥需要,文章从指挥体制和指挥方式两方面探讨了适应舰艇编队网络中心作战模式的新型指挥体系;基于网络中心作战模式下舰艇编队作战指挥特点,分析了传统指挥体制和指挥方式的不足,提出一种由动态网络型指挥体制和动态分权式指挥方式构成的新指挥体系,并分析了其在指挥可靠性、整体性和时效性方面的优势。     

锐孔气泡形成周期及影响因素的研究

气液反应器和工艺设备中存在大量的气泡,要建立准确预测气泡形成特性的计算模型,就需要详细了解气泡的形成过程,通过CLSVOF数值模拟方法配合实验验证对锐孔气泡形成过程进行了研究。着重讨论了气流量和孔径对气泡形成的影响,并研究了气泡在形成阶段的动力学特性和孔口处气泡的脱离。通过模拟数据和实验数据的分析结果,结合Fr数和Bo数关系图得出：气泡从不发生相互扰动到气泡之间发生合并与破裂的过渡阶段中,气泡锐孔处的进气速度随着孔径的增大而减小。     

基于双向最近邻准则的编队预定目标选择方法

相比传统的预定目标选择方法,基于编队形状的反舰导弹预定目标选择方法是一类性能优越的新方法。其原理是利用导弹飞行期间舰艇编队形状的相对稳定性,并将发射前装订的编队形状和末制导雷达探测到的编队形状表示为2个点集,通过点集匹配实现预定目标选择。提高这类算法性能的关键在于研究合理的点集距离函数。文章提出一种基于共同点的距离函数,研究了其抗干扰的机理,并证明其计算过程可通过双向最近邻准则实现。仿真试验表明该方法性能优于以往的MHD方法。     

基于多目标决策模型的两栖攻击舰编队编成研究

两栖攻击舰编队编成不能照搬固定的模式,而应根据作战任务和威胁等因素进行合理配置。文章分析了两栖攻击舰编队的作战能力,并在此基础上构建了编成模型的指标体系。运用多目标决策理论,建立了两栖攻击舰编队编成的模型,通过计算得到了针对某作战行动中两栖攻击舰编队的最优编成方案,并将所得到的结果与日常性建制的编队编成进行了比较。     

Formation tracking control for time-delayed multi-agent systems with second-order dynamics

In this paper, formation tracking control problems for second-order multi-agent systems (MASs) with time-varying delays are studied, specifically those where the position and velocity of followers are designed to form a time-varying formation while tracking those of the leader. A neigh-boring relative state information based formation tracking protocol with an unknown gain matrix and time-varying delays is presented. The formation tracking problems are then transformed into asymptotically stable problems. Based on the Lyapunov-Krasovskii functional approach, condi-tions sufficient for second-order MASs with time-varying delays to realize formation tracking are examined. An approach to obtain the unknown gain matrix is given and, since neighboring relative velocity information is difficult to measure in practical applications, a formation tracking protocol with time-varying delays using only neighboring relative position information is introduced. The proposed results can be used on target enclosing problems for MASs with second-order dynamics and time-varying delays. An application for target enclosing by multiple unmanned aerial vehicles (UAVs) is given to demonstrate the feasibility of theoretical results.