Stifness modeling and analysis of a novel 4-DOF PKM for manufacturing large components

Faster response to orientation varying is one of the outstanding abilities of a parallel kinematic machine（PKM）.It enables such a system to act as a reconfgurable module employed to machine large components effciently.The stiffness formulation and analysis are the beforehand key tasks for its parameters design.A novel PKM with four degrees of freedom（DOFs）is proposed in this paper.The topology behind it is 2PUS-2PRS parallel mechanism.Its semianalytical stiffness model is frstly obtained,where the generalized Jacobian matrix of 2PUS-2PRS is formulated with the help of the screw theory and the stiffness coeffcients of complicated components are estimated by integrating fnite element analysis and numerical ftting.Under the help of the model,it is predicted that the property of system stiffness distributes within the given workspace,which features symmetry about a certain plane and is also verifed by performing fnite element analysis of the virtual prototype.Furthermore,key parameters affecting the system stiffness are identifed through sensitivity analysis.These provide insights for further optimization design of this PKM.     

某型教练机机载天线与雷达罩的射线入射角的计算

随着现代高科技的发展,雷达大量应用于飞机、导弹、航海等领域．雷达罩的运用也日趋广泛。本文通过曲线拟合等一些数学分析方法,运用MATLAB工具,经过分析、编程、计算．最后得到机载天线与雷达罩的射线入射角,通过入射角的大小可判断此雷达罩是否符合要求。     

Fault self-repair strategy based on evolvable hardware and reparation balance technology

In the face of harsh natural environment applications such as earth-orbiting and deep space satellites, underwater sea vehicles, strong electromagnetic interference and temperature stress,the circuits faults appear easily. Circuit faults will inevitably lead to serious losses of availability or impeded mission success without self-repair over the mission duration. Traditional fault-repair methods based on redundant fault-tolerant technique are straightforward to implement, yet their area, power and weight cost can be excessive. Moreover they utilize all plug-in or component level circuits to realize redundant backup, such that their applicability is limited. Hence, a novel selfrepair technology based on evolvable hardware（EHW） and reparation balance technology（RBT） is proposed. Its cost is low, and fault self-repair of various circuits and devices can be realized through dynamic configuration. Making full use of the fault signals, correcting circuit can be found through EHW technique to realize the balance and compensation of the fault output-signals. In this paper, the self-repair model was analyzed which based on EHW and RBT technique, the specific self-repair strategy was studied, the corresponding self-repair circuit fault system was designed, and the typical faults were simulated and analyzed which combined with the actual electronic devices. Simulation results demonstrated that the proposed fault self-repair strategy was feasible. Compared to traditional techniques, fault self-repair based on EHW consumes fewer hardware resources, and the scope of fault self-repair was expanded significantly.     

通用的航电系统总线接口仿真平台的设计和应用

针对当前航电系统仿真器的缺点,提出了一种通用的航电系统总线接口仿真平台的设计思想,通过建立仿真数据库,从待仿真的航电系统设备中的接口信息抽象出属性和行为,然后用数据库的方式来描述,实现了仿真软件和仿真对象的分离,从而使该仿真平台具备了通用性和灵活性。该仿真平台已经在某型机航电系统地面联试中得到了应用。     

一种悬挂物兼容飞机航电与武器总线的设计方法

在某悬挂物作为通用系统挂装不同型号飞机时,由于不同型号飞机对该悬挂物采用航电和武器两种不同的总线通信方式,导致该悬挂物不能兼容挂载多型飞机。本文针对现有的总线应用情况,提出了一种悬挂物可兼容飞机不同总线通信方式的设计方案,并给出了方案的具体实现方法。     

复合材料机尾罩减重设计

根据复合材料层压板及夹层结构设计原则提出了某飞机机尾罩复合材料设计方案,结合复合材料强度计算方法进行有限元分析及强度校核。分析结果表明:在满足静强度的前提下,与金属机尾罩相比,复合材料机尾罩重量减少28.4%。     

TC4钛合金激光焊中工艺参数对气孔生成量的影响

文摘研究了TC4钛合金激光焊接在平焊、横焊两种位置下工艺参数对气孔生成量的影响。结果表明:平焊时,气孔生成量随激光功率、离焦量的增大先减小后增大,随焊接速度的增大先增大后减小;横焊时,气孔生成量随激光功率的增大而增大,随焊接速度的增大而减小,随离焦量的增大先减小后增大。利用正交试验方法得到的优化工艺参数进行焊接,气孔生成量大幅减少,在两种位置下均可得到内部质量良好的焊缝。     

液体火箭发动机初始雾化液滴分布预测

在简要描述使用最大熵原理预测初始雾化液滴分布的基础上,发展了较传统方法具有更大收敛域的数值计算方法,建立了离心式喷嘴雾化特性研究实验台,使用激光相位粒子分析仪进行了雾化粒径分布研究,结果显示实验数据同使用最大熵原理预测的分布吻合性较好,在此基础上最后提出了在液体火箭发动机雾化粒径分布预测应用中的策略。     

航空发动机涡轮前温度场数据分析方法

在航空发动机整机测试条件下,温度场测试具有局限性。介绍了1种发动机涡轮前温度场测试数据的统计分析方法,该统计方法较为有效;引入模糊原理,对统计量进行了概率分析,使得统计量评估更加完善。     

基于T-S模糊系统的空天飞行器鲁棒自适应轨迹线性化控制

 基于T-S模糊系统提出了鲁棒自适应轨迹线性化控制(RATLC)方法。利用T-S模糊系统逼近未知干扰和不确定性因素,并采用Lyapunov方法设计了鲁棒自适应控制律。不论系统状态的维数和用于逼近不确定的模糊系统规则数为多少,整个系统仅有两个参数在线调整。理论分析证明了闭环系统所有信号一致最终有界。应用提出的控制方案设计了空天飞行器(ASV)飞行控制系统,并在高超声速飞行条件下进行了仿真验证,仿真结果表明了控制方案的有效性和鲁棒性。