适用无人机的小型燃料电池控制方法

燃料电池动力系统作为一种长航时电动无人机的动力方案,其燃料电池的控制技术是决定动力系统可靠性和高效性的关键技术。针对用于无人机的小型空冷型开放阴极的质子交换膜燃料电池,考虑面向工程应用的燃料电池整体控制过程,兼顾电堆温度控制和水管理,提出了一种前馈型模糊PID的电堆温度控制方法,同时设计了一种基于安时积分门限法的膜水含量调节策略,以实现对整个燃料电池系统的高效控制。通过搭建燃料电池温度控制与水管理试验平台,对所提出的控制技术进行了试验验证,并与现有温控和水管理方法进行了对比分析。试验结果表明：所提前馈型模糊PID方法在较长时间的燃料电池启动过程中能够较快地达到目标温度,相比于PID方法减少了7%的调节时间,与传统模糊PID方法相当;燃料电池电流持续减小时,所提前馈型模糊PID方法对超调量的抑制效果具有明显优势,其超调量仅为PID方法的34%,为传统模糊PID方法的43%;所提安时积分门限排水控制方法既能防止水淹故障,又可提高燃料经济性,在所给工况中相比现有方法节约了15%的氢气。     

Topology optimization of compliant adaptive wing leading edge with composite materials

An approach for designing the compliant adaptive wing leading edge with composite material is proposed based on the topology optimization. Firstly, an equivalent constitutive relationship of laminated glass fiber reinforced epoxy composite plates has been built based on the symmetric laminated plate theory. Then, an optimization objective function of compliant adaptive wing leading edge was used to minimize the least square error（LSE） between deformed curve and desired aerodynamics shape. After that, the topology structures of wing leading edge of different glass fiber ply-orientations were obtained by using the solid isotropic material with penalization（SIMP） model and sensitivity filtering technique. The desired aerodynamics shape of compliant adaptive wing leading edge was obtained based on the proposed approach. The topology structures of wing leading edge depend on the glass fiber ply-orientation. Finally, the corresponding morphing experiment of compliant wing leading edge with composite materials was implemented, which verified the morphing capability of topology structure and illustrated the feasibility for designing compliant wing leading edge. The present paper lays the basis of ply-orientation optimization for compliant adaptive wing leading edge in unmanned aerial vehicle（UAV） field.     

小型电动无人机航程航时估算模型

小型电动无人机通常采用锂电池、无刷电机和螺旋桨组成能源动力系统,飞行过程中锂电池的实际工作电压发生变化,但飞机的总重量不变,其航程航时的估算方法与传统的燃油飞机有所不同。为了准确评估动力系统对飞机设计的影响,建立了以锂电池为动力的电动飞机推进系统模型,通过与实验数据比较,验证了各部分模型的准确性。利用该动力系统模型,对某款小型电动无人机进行了航程和航时估算,结果表明本文的建模方法准确有效,航程航时估算接近实验数据,可作为小型电动无人机设计的重要参考。     

智能材料和结构在变体飞行器上的应用现状与前景展望简

 变体飞行器可以根据不同的飞行条件改变自身形状以获得最优的气动性能,大大提高飞行器的综合性能,是未来飞行器发展的重要方向之一。新型智能材料和结构具有驱动、变形、承载、传感等特点,为变体飞行器的设计提供了新的技术途径。本文根据不同可变形机翼结构分类,详细阐述了智能材料和结构在自适应结构、智能驱动器和变形蒙皮等方面的研究现状。变体飞行器的实现亟需解决变形/承载一体化蒙皮技术、轻质大输出力驱动器技术和自适应结构技术等关键技术,本文还对智能材料和结构未来在变体飞行器上的应用前景进行了展望。     

智能材料和结构在变体飞行器上的应用现状与前景展望

变体飞行器可以根据不同的飞行条件改变自身形状以获得最优的气动性能,大大提高飞行器的综合性能,是未来飞行器发展的重要方向之一。新型智能材料和结构具有驱动、变形、承载、传感等特点,为变体飞行器的设计提供了新的技术途径。本文根据不同可变形机翼结构分类,详细阐述了智能材料和结构在自适应结构、智能驱动器和变形蒙皮等方面的研究现状。变体飞行器的实现亟需解决变形/承载一体化蒙皮技术、轻质大输出力驱动器技术和自适应结构技术等关键技术,本文还对智能材料和结构未来在变体飞行器上的应用前景进行了展望。     

涵道风扇式无人机的优先级控制分配

涵道风扇式无人机是一种冗余配置操纵面的飞行器,其控制分配问题通常使用伪逆法求解,然而伪逆法不能对任意可达的期望力矩都返回容许控制,使冗余的操纵面牺牲了部分控制能力。提出一种优先级控制分配方法,该方法先对期望力矩进行矢量分解并划分优先级,再求解约束最优化问题得到容许控制。相比于伪逆法,所提出的方法可对更大范围的期望力矩返回容许控制,而且当期望力矩不可达时,可以防止系统因执行器饱和而产生输出耦合。将所提出的方法应用到涵道风扇式无人机的控制分配中,仿真及飞行试验验证了该方法的有效性。     

Delaying stall of morphing wing by periodic trailing-edge deflection

Morphing wings can improve aircraft performance during different flight phases. Recently research has focused on steady aerodynamic characteristics of the morphing wing with a flexible trailing-edge, and the unsteady aerodynamic and stall characteristics in the deflection process of the morphing wing are worthy further investigation. The effects of the angle of attack and deflection rate on aerodynamic characteristics were examined, and based on the aerodynamic characteristics of the morphing wing, a method was developed to delay stall by using the flexible periodic trailing-edge deflection. The numerical results show that the lift coefficients in the deflection process are smaller than those in the static situation at small angles of attack, and that the higher the deflection rate is, the smaller the lift coefficients will be. On the contrary, at large angles of attack, the lift coefficients are higher than those in the static case, and they become larger with the increase of the deflection rate. Further, the periodic deflection of the flexible trailing-edge with a small deflection amplitude and high deflection rate can increase lift coefficients at the critical stall angle.     

In-plane corrugated cosine honeycomb for 1D morphing skin and its application on variable camber wing

A novel 0-Poisson’s ratio cosine honeycomb support structure of flexible skin is proposed. Mechanical model of the structure is analyzed with the energy method, finite element method (FEM) and experiments have been performed to validate the theoretical model. The in-plane characteristics of the cosine honeycomb are compared with accordion honeycomb through analytical models and experiments. Finally, the application of the cosine honeycomb on a variable camber wing is studied. Studies show that mechanical model agrees well with results of FEM and experiments. The transverse non-dimensional elastic modulus of the cosine honeycomb increases (decreases) when the wavelength or the wall width increases (decreases), or when the amplitude decreases (increases). Compared with accordion honeycomb, the transverse non-dimensional elastic modulus of the cosine honeycomb is smaller, which means the driving force is smaller and the power consumption is less during deformation. In addition, the cosine honeycomb can satisfy the deform- ing requirements of the variable camber wing.     

燃料电池无人机动力系统方案设计与试验

针对燃料电池为主能源的无人机（UAV）动力系统,设计了纯燃料电池动力系统、燃料电池/蓄电池（简称燃蓄）被/主动混合动力系统3种拓扑结构方案。以空冷质子交换膜燃料电池为例,搭建了燃料电池动力系统方案一体化试验平台。考虑阶梯型和阶跃型2种加载形式,试验研究了燃料电池自身的动态特性和启动特性。以阶梯型功率剖面的加载形式,试验研究了纯燃料电池动力系统放电特性;以无人机典型任务剖面作为加载形式,开展燃蓄被/主动混合动力系统对比试验研究。试验结果表明：纯燃料电池动力方案适用于低机动小型无人机,燃蓄被动混合方案可满足小型无人机大机动飞行,燃蓄主动混合方案系统可适应中大型无人机更长航时飞行。     

多无人机协同覆盖路径规划

多无人机协同覆盖路径规划(CPP)由于其并行性和容错能力,对于提高无人机完成侦察、监视、搜索等任务的效率具有重要意义。提出了一种基于无人机任务性能评价和任务区域划分的多无人机协同CPP算法。定量分析了无人机执行覆盖任务的能力,根据无人机及携带成像传感器的性能给出了计算无人机任务性能指数的数学公式;提出了一种基于任务性能和子区域宽度的任务区域划分算法,使无人机的总转弯次数达到最少。仿真结果表明,所提出的CPP算法能够规划出全局最优的多无人机协同覆盖路径。     

燃料电池无人机能源管理与飞行状态耦合

开展了燃料电池/锂电池（简称燃锂）混合动力无人机的能源管理与飞行状态耦合研究。综合顶层飞行任务规划与底层能源系统管理,以动力系统模型为耦合点联立能源系统与无人机运动方程,建立能源状态与运动状态耦合模型。针对燃锂混合最紧密的爬升过程,以迎角、转速和燃料电池的放电功率作为控制变量,建立了燃料消耗最小的能源管理与航迹规划耦合最优控制问题,研究不同爬升高度对最优控制过程的影响,并与模糊控制能源管理策略进行对比分析。针对大功率短时爬升和小功率长时巡航的典型任务特点,建立了燃锂最优混合问题。研究了最优的锂电池容量和燃料电池功率水平的混合量,以及爬升和巡航两阶段最优功率分配和飞行状态,分析了不同巡航目标高度对最优混合量和飞行状态的影响。结果表明：采用能源与航迹耦合的最优控制策略在给出最优功率流分配的同时,能够很好地兼顾飞行状态控制;对燃锂混合和飞行状态的综合优化可以有效地处理爬升和巡航阶段的能源需求矛盾,在给出最优燃锂混合量和飞行状态的同时,降低整个任务过程的燃料消耗。     

面向林火持续侦察的多无人机分布式控制方法

为解决目前面向林火持续侦察多无人机（UAV）协同控制实用性与自主性不足的问题,基于蔓延速度诱导元胞自动机（SVICA）林火蔓延算法、无人机与传感器建模,构建了较为真实的三维多无人机火场侦察仿真环境与侦察效能指标,提出了一种面向林火持续侦察的多无人机双层分布式控制架构,在行动层基于强化学习训练的人工神经网络（ANN）,实现了有风条件下无人机自主火场环绕与地形跟随功能,在策略层设计通过时域均匀分布算法进行各无人机空速的离散自主调节,最终达到多无人机林火持续侦察时域分布的均匀性与即时性目的。通过一系列数值仿真实验,验证了所提出的无人机分布控制策略在无人机损失和补充突发情况下的自适应性。基于无人机数量与侦察效能指标关系的实验与研究,定义了无人机出动阈值并验证了无人机长时间出动回收策略。最终实验结果表明,针对林火持续侦察任务,所提出的多无人机分布式控制方法具备一定的有效性与实用性。     

Optimization of aerodynamic efficiency for twist morphing MAV wing

Twist morphing(TM) is a practical control technique in micro air vehicle(MAV) flight.However, TM wing has a lower aerodynamic efficiency(CL/CD) compared to membrane and rigid wing. This is due to massive drag penalty created on TM wing, which had overwhelmed the successive increase in its lift generation. Therefore, further CL/CDmaxoptimization on TM wing is needed to obtain the optimal condition for the morphing wing configuration. In this paper, two-way fluid–structure interaction(FSI) simulation and wind tunnel testing method are used to solve and study the basic wing aerodynamic performance over(non-optimal) TM, membrane and rigid wings. Then,a multifidelity data metamodel based design optimization(MBDO) process is adopted based on the Ansys-DesignXplorer frameworks. In the adaptive MBDO process, Kriging metamodel is used to construct the final multifidelity CL/CDresponses by utilizing 23 multi-fidelity sample points from the FSI simulation and experimental data. The optimization results show that the optimal TM wing configuration is able to produce better CL/CDmaxmagnitude by at least 2% than the non-optimal TM wings. The flow structure formation reveals that low TV strength on the optimal TM wing induces low CDgeneration which in turn improves its overall CL/CDmaxperformance.     

考虑输入饱和的固定翼无人机自适应增益滑模控制

针对复杂环境下的固定翼无人机飞行控制问题,考虑输入饱和以及复杂外界干扰的影响,提出一种基于自适应滑模控制方法的固定翼无人机飞行控制策略。首先,对固定翼无人机模型进行介绍,将模型分为姿态子系统和速度子系统;其次,针对姿态子系统和速度子系统的特点以及控制需求,分别采用自适应多变量螺旋滑模和自适应快速超螺旋滑模设计姿态控制器和速度控制器,该策略无需设计干扰观测器对外界干扰进行估计,仍然可以实现固定翼无人机对姿态参考指令和速度参考指令的有限时间精确跟踪,并基于Lyapunov的稳定性分析方法证明了闭环系统的稳定性。最后,对本文所提出的控制策略进行了仿真验证,结果表明该控制策略具有良好的控制性能。     

飞翼布局无人机变形机翼设计与模型验证研究

对飞翼布局无人机变形机翼和变形机翼传动机构进行了设计,根据设计结果制作验证模型进行风洞实验和外场飞行试验,以此研究伸缩段机翼对飞行器机翼整体气动性能的影响。结果表明:采用变形机翼技术,可以通过实时控制机翼的气动外形保持较高的气动效率,提高飞机在巡航状态下的升力和高速飞行状态下的机动性,满足飞机在各种任务剖面的战术性能要求。     

Integrated optimization design of smart morphing wing for accurate shape control

Smart morphing wing, which is equipped with smart materials and able to change structural geometry adaptively, can further improve aerodynamic efficiency of aircraft. This paper presents a new integrated layout and topology optimization design for morphing wing driven by shape memory alloys (SMAs). By simultaneously optimizing the layout of smart actuators and topology of wing substrate, the ultimately determined configuration can achieve smooth, continuous and accurate geometric shape changes. In addition, aerodynamic analysis is carried out to compare smart morphing wing with traditional hinged airfoil. Finally, the optimized smart wing structure is constructed and tested to demonstrate and verify the morphing functionality. Application setbacks are also pointed out for further investigation.     

Integrated design of topology and material for composite morphing trailing edge based compliant mechanism

The morphing trailing edge based compliant mechanism is a developing technology which can increase lift-drag ratio for variable flight modes by bending down the trailing edge. Composite material design is integrated into topology optimization for the morphing trailing edge based compliant mechanism in the paper. A two-step optimization strategy is established to solve the integrated design problem. Initially, lamination parameters are introduced and viewed as a bridge between structure stiffness and fiber angles for composite material. Design variables include the lamination parameters and element density. The least-squares between actual and desired displacements at output points along trailing edge is adopted to evaluate the deformed capability of the trailing edge. An integrated optimization model for the composite morphing trailing edge is established with the volume constraints. The optimal topologic shape and lamination parameters are initially obtained. Subsequently, a least-squares optimization between fiber angles and the optimal lamination parameters is implemented to obtain optimal fiber angles. Finally, morphing capability of composites trailing edge based compliant mechanism is investigated by simulation and experiments. The results indicate the composites trailing edge based compliant mechanism can approximately bend down 8 degrees and satisfies the design requirement.     

Virtual target guidance-based distributed model predictive control for formation control of multiple UAVs

The paper proposes a Virtual Target Guidance(VTG)-based distributed Model Predictive Control(MPC) scheme for formation control of multiple Unmanned Aerial Vehicles(UAVs).First, a framework of distributed MPC scheme is designed in which each UAV only shares the information with its neighbors, and the obtained local Finite-Horizon Optimal Control Problem(FHOCP) can be solved by swarm intelligent optimization algorithm.Then, a VTG approach is developed and integrated into the distributed MPC scheme...     

Collision free 4D path planning for multiple UAVs based on spatial refined voting mechanism and PSO approach

In this paper, a four-dimensional coordinated path planning algorithm for multiple UAVs is proposed, in which time variable is taken into account for each UAV as well as collision free and obstacle avoidance. A Spatial Refined Voting Mechanism(SRVM) is designed for standard Particle Swarm Optimization(PSO) to overcome the defects of local optimal and slow convergence.For each generation candidate particle positions are recorded and an adaptive cube is formed with own adaptive side length to indicate occupied regions. Then space voting begins and is sorted based on voting results, whose centers with bigger voting counts are seen as sub-optimal positions. The average of all particles of corresponding dimensions are calculated as the refined solutions. A time coordination method is developed by generating specified candidate paths for every UAV, making them arrive the same destination with the same time consumption. A spatial-temporal collision avoidance technique is introduced to make collision free. Distance to destination is constructed to improve the searching accuracy and velocity of particles. In addition, the objective function is redesigned by considering the obstacle and threat avoidance, Estimated Time of Arrival(ETA), separation maintenance and UAV self-constraints. Experimental results prove the effectiveness and efficiency of the algorithm.     

某小型无人机编队控制器设计及试飞验证

以某小型固定翼无人机作为研究平台,按前向、侧向和垂直方向3个通道设计僚机编队控制器.利用自动驾驶仪的航路飞行模态简化侧向通道编队控制器的设计,并采用在长机航向角发生较大变化时加入基于视线方位角的方法,使僚机保持编队精度.试验结果表明,所提出的编队算法是可用的,并能够很好地控制无人机的编队飞行精度.