Two-layer formation-containment fault-tolerant control of fixed-wing UAV swarm for dynamic target tracking

This paper tackles the formation-containment control problem of fixed-wing unmanned aerial vehicle(UAV)swarm with model uncertainties for dynamic target tracking in three-dimensional space in the faulty case of UAVs’actuator and sensor.The fixed-wing UAV swarm under consideration is organized as a“multi-leader-multi-follower”structure,in which only several leaders can obtain the dynamic target information while others only receive the neighbors’information through the communication network.To simultaneously realize the formation,containment,and dynamic target tracking,a two-layer control framework is adopted to decouple the problem into two subproblems:reference trajectory generation and trajectory tracking.In the upper layer,a distributed finite-time estimator(DFTE)is proposed to generate each UAV’s reference trajectory in accordance with the control objective.Subsequently,a distributed composite robust fault-tolerant trajectory tracking controller is developed in the lower layer,where a novel adaptive extended super-twisting(AESTW)algorithm with a finite-time extended state observer(FTESO)is involved in solving the robust trajectory tracking control problem under model uncertainties,actuator,and sensor faults.The proposed controller simultaneously guarantees rapidness and enhances the system’s robustness with fewer chattering effects.Finally,corresponding simulations are carried out to demonstrate the effectiveness and competitiveness of the proposed two-layer fault-tolerant cooperative control scheme.

Radio Controlled “3D Aerobatic Airplanes” as Basis for Fixed-Wing UAVs with VTOL Capability

There are fundamental performance compromises between rotary-wing and fixed-wing UAVs. The general solution to address this well-known problem is the design of a platform with some degree of reconfigurable airframes. For critical missions (civilian or military), it is imperative that mechanical complexity is kept to a minimum to help achieve mission success. This work proposes that the tried-and-true radio controlled (RC) aerobatic airplanes can be implemented as basis for fixed-wing UAVs having both speed and vertical takeoff and landing (VTOL) capabilities. These powerful and highly maneuverable airplanes have non-rotatable nacelles, yet capable of deep stall maneuvers. The power requirements for VTOL and level flight of an aerobatic RC airplane are evaluated and they are compared to those of a RC helicopter of similar flying weight. This work provides quantitative validation that commercially available RC aerobatic airplanes can serve as platform to build VTOL capable fixed-wing UAVs that are agile, cost effective, reliable and easy maintenance.

Affine formation tracking control of unmanned aerial vehicles

The affine formation tracking problem for fixed-wing unmanned aerial vehicles(UAVs)is considered in this paper,where fixed-wing UAVs are modeled as unicycle-type agents with asymmetrical speed constraints.A group of UAVs are required to generate and track a time-varying target formation obtained by affinely transforming a nominal formation.To handle this problem,a distributed control law based on stress matrix is proposed under the leader-follower control scheme.It is proved,theoretically,that followers can converge to the desired positions and achieve affine transformations while tracking diverse trajectories.Furthermore,a saturated control strategy is proposed to meet the speed constraints of fixed-wing UAVs,and numerical simulations are executed to verify the effectiveness of our proposed affine formation tracking control strategy in improving maneuverability.

BIM技术在新建鲁南高铁跨越营业线施工中的应用

针对本工程存在的铁路营业线空间位置难以确定、施工安全风险大、要点施工效率要求高、零号块施工难度大等重难点,通过制定详细的实施方案、执行计划作为项目实施的指导性文件,应用无人机、三维扫描仪等设备采集营业线施工重点区域点云数据,校核工程空间位置关系;建立颗粒度高的营业线、零号块钢筋、新建特大桥、施工深化等BIM模型,基于BIM模型开展碰撞检查、施工方案可行性研究及深化;针对转体施工、中跨钢盒吊装等施工重难点进行BIM虚拟仿真,优化高风险工序,辅助天窗施工方案审查;转体施工过程中将BIM与物联网技术相结合,实时监测并控制梁体间的安全距离。本项目的BIM深度应用,有效降低了营业线施工的安全风险,保证施工质量和效率,应用成果形成铁路营业线施工工艺工法库并完成数字化交付,为后续类似铁路营业线项目提供参考。

先进复合材料在军用固定翼飞机上的发展历程及前景展望

复合材料以其卓越的性能和优秀的可设计性成为令人瞩目的材料体系。先进树脂基复合材料是目前航空领域广泛使用的材料。本文回顾了先进复合材料在国外固定翼航空器上的发展历程,对其在国内外飞机上的应用进行了分析,最后结合其在国内固定翼航空器上的发展历程,分析了目前先进复合材料发展遇到的问题,并从复合材料设计、制造、人才建设、基础技术研究和理念等方面对复合材料行业迅速发展提出一些建议。

Prediction of electric-powered fixed-wing UAV endurance

To overcome the problems encountered in predicting the endurance of electricpowered fixed-wing unmanned aerial vehicles(UAVs),which were stemmed from the dynamic changes in electric power system efficiency and battery discharge characteristics under different operating conditions,the required battery power model and battery discharge model were studied.The required battery power model was determined using an approximate model of electric power system efficiency based on wind tunnel testing and the self-adaptive penalty function.Furthermore,current correction and ambient temperature correction terms were proposed for the trained Kriging model representing the discharge characteristics under standard operation,and then the discharged capacity-terminal voltage model was established.Through numerical integration of this model with the required battery power model,the electric-powered fixed-wing UAV endurance prediction model was obtained.Laboratory tests indicated that the proposed endurance model could precisely calculate the battery discharge time and accurately describe the battery discharge process.The similarity of the theoretical and flight test results reflected the accuracy of the proposed endurance model as well as the importance of considering dynamic changes in power system efficiency in endurance calculations.The proposed endurance model meeting precision requirements can be used in practical engineering applications.

固定翼无人机综合实践教学设计研究

围绕知识—能力—素质培养理念,在航空院校配合无人机设计课程开展综合实践,设定学生应该具备的能力标准,以项目设计为抓手,将理论知识点和关键能力点有机串联,通过动手操作及无人机实飞,综合提高学生对知识的理解水平和应用能力,通过良好的习惯培养航空素养。结合国防科技大学实际,开展基于固定翼无人机为实践平台的综合实践教学设计与实践,带领学生完成气动计算、通信测控、飞行控制、总装集成,并开展无人机实际飞行验证;总结了授课体会并延伸改革思路,对无人机专业学生的任职教育与教改模式创新具有较好的参考意义。