Towards efficient flight: insights on proper morphing-wing modulation in a bat-like robot

In this article, we address the question of how the flight efficiency of Micro Aerial Vehicles with variable wing geometry can be inspired by the biomechanics of bats. We use a bat-like drone with highly articulated wings using shape memory alloys (SMA) as artificial muscle-like actuators. The possibility of actively changing the wing shape by controlling the SMA actuators, let us study the effects of different wing modulation patterns on lift generation, drag reduction, and the energy cost of a wingbeat cycle. To this purpose, we present an energy-model for estimating the energy cost required by the wings during a wingbeat cycle, using experimental aerodynamic and inertial force data as inputs to the energy-model. Results allowed us determining that faster contraction of the wings during the upstroke, and slower extension during the downstroke enables to reduce the energy cost of flapping in our prototype.     

Development of a Flying Robot With a Pantograph-Based Variable Wing Mechanism

We develop a flying robot with a new pantograph-based variable wing mechanism for horizontal-axis rotorcrafts (cyclogyro rotorcrafts). A key feature of the new mechanism is to have a unique trajectory of variable wings that not only change angles of attack but also expand and contract according to wing positions. As a first step, this paper focuses on demonstrating the possibility of the flying robot with this mechanism. After addressing the pantograph-based variable wing mechanism and its features, a simulation model of this mechanism is constructed. Next, we present some comparison results (between the simulation model and experimental data) for a prototype body with the proposed pantograph-based variable wing mechanism. Both simulation and experimental results show that the flying robot with this new mechanism can generate enough lift forces to keep itself in the air. Furthermore, we construct a more precise simulation model by considering rotational motion of each wing. As a result of optimizing design parameters using the precise simulation model, flight performance experimental results demonstrate that the robot with the optimal design parameters can generate not only enough lift forces but a 155 gf payload as well.      

Passive torque regulation in an underactuated flapping wing robotic insect

Recent developments in millimeter-scale fabrication processes have led to rapid progress towards creating airborne flapping wing robots based on Dipteran (two winged) insects. Previous work to regulate forces and torques generated by flapping wings has focused on controlling wing trajectory. An alternative approach uses underactuated mechanisms with tuned dynamics to passively regulate these forces and torques. The resulting ??mechanically intelligent?? devices execute wing trajectory corrections to realize desired body forces and torques without the intervention of an active controller. This article describes an insect-scale flapping wing mechanism consisting of a single piezoelectric actuator, an underactuated transmission, and passively rotating wings. Wing stroke velocities are passively modulated to eliminate net airframe roll torque. A theoretical model predicts lift generating wing trajectories and quantifies the passive reduction in roll torque. An experimental structure provides an at-scale demonstration of passive torque regulation.     

三铰扑翼建模及数值计算

为研究鸟类翅膀展向变形对扑翼气动特性的影响,基于对鸟类翅膀变形的观察,分别用动静法和拉格朗日方程建立三铰扑翼的数学模型,并利用数值计算研究该模型.结果表明：使用NACA0004作为截面的三铰扑翼在对称扑动时能够产生净升力;随着中翼弹性系数比的增大,周期平均升力因数增大,但周期平均阻力因数不存在单调性;三铰扑翼比双铰翼的周期平均升力因数明显小;随着外翼弹性系数比的增大,周期平均升力因数和周期平均阻力因数也不存在单调特性.     

Variable thrust directional control technique for plateau unmanned aerial vehicles高原型无人机变推力轴线控制技术研究

In order to increase the lift force of the unmanned aerial vehicles (UAV) in plateau areas, the UAV is commonly equipped with high span chord ratio wings. However, it may decrease the maneuverability of the aircraft, and thus increasing the risk of flight in complex terrain regions. Thrust vector control is a direct force flight control technique, which enhances the maneuverability and introduces the residual of the flight control system. In this paper, we develop a novel variable thrust direction mechanism, which provides the normal propeller UAV with the capability of directional force control. We propose a combinational flight control strategy for the newly developed UAV. Simulations and real flight test demonstrate the performance of the proposed technique in increasing the maneuverability of the conventional propeller UAV.     

Vortex visualization in ultra low Reynolds number insect flight

We present the visual analysis of a biologically inspired CFD simulation of the deformable flapping wings of a dragonfly as it takes off and begins to maneuver, using vortex detection and integration-based flow lines. The additional seed placement and perceptual challenges introduced by having multiple dynamically deforming objects in the highly unsteady 3D flow domain are addressed. A brief overview of the high speed photogrammetry setup used to capture the dragonfly takeoff, parametric surfaces used for wing reconstruction, CFD solver and underlying flapping flight theory is presented to clarify the importance of several unsteady flight mechanisms, such as the leading edge vortex, that are captured visually. A novel interactive seed placement method is used to simplify the generation of seed curves that stay in the vicinity of relevant flow phenomena as they move with the flapping wings. This method allows a user to define and evaluate the quality of a seed's trajectory over time while working with a single time step. The seed curves are then used to place particles, streamlines and generalized streak lines. The novel concept of flowing seeds is also introduced in order to add visual context about the instantaneous vector fields surrounding smoothly animate streak lines. Tests show this method to be particularly effective at visually capturing vortices that move quickly or that exist for a very brief period of time. In addition, an automatic camera animation method is used to address occlusion issues caused when animating the immersed wing boundaries alongside many geometric flow lines. Each visualization method is presented at multiple time steps during the up-stroke and down-stroke to highlight the formation, attachment and shedding of the leading edge vortices in pairs of wings. Also, the visualizations show evidence of wake capture at stroke reversal which suggests the existence of previously unknown unsteady lift generation mechanisms that are unique to quad wing insects.     

Z型折叠机翼的非线性动力学与模态分析研究

针对Z型折叠机翼这种复杂多体结构,运用多种不同的方法得到了结构的前4阶振动模态.将Z型折叠机翼假设为由三块碳纤维复合材料板组成,两板之间均以刚性铰链相连接.其中内翼左侧是固定端,并与机身相连接;中间翼以对边简支形式连接在内外翼之间;外翼的外端是自由端.在第一个铰链上施加驱动力矩M1为机翼提供折叠角速度,使中间翼进行转动;同时施加力矩M2于第二个铰链处,使外翼与内翼始终保持平行.本文首先利用Hamilton原理与von Karman大变形理论建立Z型折叠机翼的动力学模型,然后通过ANSYS软件设置合理的边界条件进行模态分析与谐响应分析,其次根据ANSYS模拟的Z型折叠机翼的振动形式,假设合适的模态函数,通过结构边界条件和系统动力学方程求出来的边界条件,求出三个板的横向振动模态函数,最后通过Maple验证得出的模态函数与ANSYS模拟的振动形式相符合.该研究不仅是Z型机翼的受迫振动响应分析的前提,而且对于Z型机翼的设计与实验也具有参考价值.     

Modeling and Trajectory Tracking Control for Flapping-Wing Micro Aerial Vehicles

This paper studies the trajectory tracking problem of flapping-wing micro aerial vehicles(FWMAVs)in the longitudinal plane.First of all,the kinematics and dynamics of the FWMAV are established,wherein the aerodynamic force and torque generated by flapping wings and the tail wing are explicitly formulated with respect to the flapping frequency of the wings and the degree of tail wing inclination.To achieve autonomous tracking,an adaptive control scheme is proposed under the hierarchical framework.Specifically,a bounded position controller with hyperbolic tangent functions is designed to produce the desired aerodynamic force,and a pitch command is extracted from the designed position controller.Next,an adaptive attitude controller is designed to track the extracted pitch command,where a radial basis function neural network is introduced to approximate the unknown aerodynamic perturbation torque.Finally,the flapping frequency of the wings and the degree of tail wing inclination are calculated from the designed position and attitude controllers,respectively.In terms of Lyapunov's direct method,it is shown that the tracking errors are bounded and ultimately converge to a small neighborhood around the origin.Simulations are carried out to verify the effectiveness of the proposed control scheme.     

Mechanical principles of dynamic terrestrial self-righting using wings

Terrestrial animals and robots are susceptible to flipping-over during rapid locomotion in complex terrains. However, small robots are less capable of self-righting from an upside-down orientation compared to small animals like insects. Inspired by the winged discoid cockroach, we designed a new robot that opens its wings to self-right by pushing against the ground. We used this robot to systematically test how self-righting performance depends on wing opening magnitude, speed, and asymmetry, and modeled how kinematic and energetic requirements depend on wing shape and body/wing mass distribution. We discovered that the robot self-rights dynamically using kinetic energy to overcome potential energy barriers, that larger and faster symmetric wing opening increases self-righting performance, and that opening wings asymmetrically increases righting probability when wing opening is small. Our results suggested that the discoid cockroach’s winged self-righting is a dynamic maneuver. While the thin, lightweight wings of the discoid cockroach and our robot are energetically sub-optimal for self-righting compared to tall, heavy ones, their ability to open wings saves them substantial energy compared to if they had static shells. Analogous to biological exaptations, our study provided a proof-of-concept for terrestrial robots to use existing morphology in novel ways to overcome new locomotor challenges.     

Peer-to-Peer环境下的信任模型研究

开放、共享、匿名的peer-to-peer网络已经取得了越来越多的应用,无中心对等的特性也吸引了越来越多的用户,但同时也成为了网络攻击者传播恶意内容或病毒的温床。由于其网络中的节点不受约束,节点间存在着自愿的交易行为,因此节点之间的信任很难通过传统网络的机制来制约和建立。本文旨在通过借鉴人类社会网络中的信任关系来建立一种信任模型,通过定义一系列信任的因子,用以制约用户行为,同时为用户寻求服务前提供参考。最后通过和其他信任模型的对比,我们的模型能够有效地激励用户提供反馈,遏制节点的不诚实行为。     

折叠翼的理论建模与实验研究

折叠翼是可变体飞行器设计最有前景的方案之一.在折叠变形过程中,飞行器的气动特性以及振动特性将会发生变化.为了研究折叠翼可变体飞行器机翼的振动特性,本文设计制作了折叠板结构,介绍了建立复杂结构力学模型的方法,用力学实验得到用于离散折叠板结构的低阶模态,并且考察了系统可能存在的内共振频率.     

Modeling Synchronous Muscle Function in Insect Flight: a Bio-Inspired Approach to Force Control in Flapping-Wing MAVs

Micro-aerial vehicles (MAV) and their promising applications—such as undetected surveillance or exploration of environments with little space for land-based maneuvers—are a well-known topic in the field of aerial robotics. Inspired by high maneuverability and agile flight of insects, over the past two decades a significant amount of effort has been dedicated to research on flapping-wing MAVs, most of which aim to address unique challenges in morphological construction, force production, and control strategy. Although remarkable solutions have been found for sufficient lift generation, effective methods for motion control still remain an open problem. The focus of this paper is to investigate general flight control mechanisms that are potentially used by real insects, thereby providing inspirations for flapping-wing MAV control. Through modeling the insect flight muscles, we show that stiffness and set point of the wing’s joint can be respectively tuned to regulate the wing’s lift and thrust forces. Therefore, employing a suitable controller with variable impedance actuators at each wing joint is a prospective approach to agile flight control of insect-inspired MAVs. The results of simulated flight experiments with one such controller are provided and support our claim.     

一种基于神经网络的垃圾邮件过滤方法

垃圾邮件问题日益严重,受到研究人员的广泛关注,基于各种技术的垃圾邮件过滤方法应运而生,其中神经网络技术应用广泛.现在主要采用的后向传播(BP)神经网络虽然在垃圾邮件过滤中取得很好的效果,但仍然存在局部极小点、不能适应新样本、学习效率较低等诸多问题.因此,本文将一种有导师、可在线学习的自组织神经网络--预测自适应谐振理论神经网络(ARTMAP),运用于垃圾邮件过滤,提出了一种新的基于ARTMAP的垃圾邮件过滤方法.实验表明,基于ARTMAP的邮件过滤能够对垃圾邮件进行有效的过滤,在保证正确率的同时,更能适应当前垃圾邮件特征不断变化的环境.     

A Computational Fluid Dynamics （CFD） Analysis of an Undulatory Mechanical Fin Driven by Shape Memory Alloy

Many fishes use undulatory fin to propel themselves in the underwater environment. These locomotor mechanisms have a popular interest to many researchers. In the present study, we perform a three-dimensional unsteady computation of an undulatory mechanical fin that is driven by Shape Memory Alloy (SMA). The objective of the computation is to investigate the fluid dynamics of force production associated with the undulatory mechanical fin. An unstructured, grid-based, unsteady Navier-Stokes solver with automatic adaptive remeshing is used to compute the unsteady flow around the fin through five complete cycles. The pressure distribution on fin surface is computed and integrated to provide fin forces which are decomposed into lift and thrust. The velocity field is also computed throughout the swimming cycle. Finally,a comparison is conducted to reveal the dynamics of force generation according to the kinematic parameters of the undulatory fin (amplitude, frequency and wavelength).     

From biological consciousness to machine consciousness: An approach to make smarter machines

Consciousness research has been of great concern to philosophers, psychologists and neuroscientists in recent years. At the same time, consciousness has also attracted more and more interest of artificial intelligence （AI） researchers. In order to make more intelligent machines, many computing models of machine consciousness have been presented. Furthermore, self-consciousness has relevance to the level of intelligent functions. Hence, it is necessary to study self-consciousness in AI. This thesis, starting from biological consciousness, discusses some viewpoints of machine consciousness. Based on the discussions, we present a way to emulate self-consciousness and test this method via simulation experiments. Our results indicate that self-consciousness, which belongs to organisms, can he imitated by machines.     

WHAT IT MEANS TO BE "SITUATED"

Situated action is a new approach to artificial intelligence that has thus far functioned without any explicit underlying theoretical foundation. As a result, many researchers in artificial intelligence have misunderstood the goals and claims of situated action. In order to rectify this situation, we provide an explicit formulation of the theoretical foundations of situated action.     

Dissection of a Flexible Wing's Performance for Insect-Inspired Flapping-Wing Micro Air Vehicles

We present a computational study on the aerodynamic performance of flexible wings aiming to facilitate the design of insect-inspired flapping-wing micro air vehicles (FMAVs). First, we propose using a two-dimensional mechanical model for a flapping wing to help understand the mechanism underlying its unsteady deformation when exposed to aerodynamic and inertia forces. This is followed by comparative analyses of both flexible wings and fixed wings in flight. In particular, a 'swaying propulsion' mechanism is proposed to mimic the flapping of the winged insects, and a new concept of 'initial torsion angle' is introduced to provide an equivalent means to account for the asymmetry of the torsional stiffness of the thorax muscle during upstroke and downstroke flapping. Subsequently, the aerodynamic forces and power requirements for a bumblebee's wings under various flight conditions are systematically examined. Our results indicate that flexibility of the wings largely contributes to the high lifts and that gliding forces play a significant role in improving flight performance, suggesting that optimal design of the structure and flapping motions of wings could achieve improved efficiency in FMAVs. These studies promote a brand new design concept for future insect-inspired FMAVs.     

The designability of protein structures

It has been noted that natural proteins adapt only a limited number of folds. Several researchers have investigated why and how nature has selected this small number of folds. Using simple models of protein folding, we demonstrate systematically that there is a "designability principle" behind nature's selection of protein folds. The designability of a structure (fold) is measured by the number of sequences that can design the structure--that is, sequences that possess the structure as their unique ground state. Structures differ drastically in terms of their designability. A small number of highly designable structures emerge with a number of associated sequences much larger than the average. These highly designable structures possess proteinlike secondary structures, motifs, and even tertiary symmetries. In addition, they are thermodynamically more stable and fold faster than other structures. These results suggest that protein structures are selected in nature because they are readily designed and stable against mutations, and that such a selection simultaneously leads to thermodynamic stability.     

人工智能领域知识图谱构建与分析

近年来人工智能技术成为学术界和产业界的研究焦点,基于领域科技文献对人工智能相关技术脉络的发展进行分析和研究有助于科研人员掌握相关技术发展方向,同时为国家制定相关政策措施提供了大数据支撑。美国人工智能协会年会(AAAI)和人工智能国际联合大会(IJCAI)是人工智能领域最主要的学术会议,众多领先的AI科技成果在上述会议期间被提出。论文对最近十余年的AAAI和IJCAI会议中的论文集进行了整理分析和挖掘,构建了包含500000个反映研究主题、研究人员等实体及其关系的三元组的人工智能领域知识图谱,并在此基础上对人工智能领域的研究热点和发展趋势进行了分析和讨论。     

泛逻辑学理论——机制主义人工智能理论的逻辑基础

当前，世界各主要大国都把人工智能作为它们的国家战略。人工智能的发展正在快速改变着人类的生活方式和思想观念。在中国，有一小批研究者20多年来一直在基于辩证唯物主义潜心研究具有普适性的人工智能基础理论，包括智能的形成机制、逻辑基础、数学基础、协调机理、矛盾转化等。终于，他们各自建立了机制主义人工智能理论、泛逻辑学理论、因素空间理论、协调学、可拓学、集对分析等。其中，机制主义人工智能理论是基于智能形成机制的通用理论，它能把现有的结构主义、功能主义和行为主义三大流派有机地统一起来，使意识、情感、理智成为三位一体的关系；因素空间理论是机制主义人工智能理论的数学基础；泛逻辑学理论是机制主义人工智能理论的逻辑基础。本文介绍了泛逻辑学理论的基本思想、理论基础和应用方法，阐明它的理论意义和应用价值。特别需要指出的是，在广义概率论基础上建立的命题泛逻辑（包括刚性逻辑和柔性逻辑），可看成一个完整的命题级智能信息处理算子库，库中完整地包含了全部18种柔性信息处理模式（包括16种布尔信息处理模式），可用类型编码<a,b,e>来严格区分，用它可寻找到适合自己的信息处理算子完整簇来使用。在每一个信息处理模式中，各种不确定性的组合状态由不确定性程度属性编码<k,h,β,e>来严格区分，用它可在本信息处理模式的算子完整簇中精确选择具体的算子来使用。这表明柔性信息处理本质上是一把密码锁，它需要专门的密码<a,b,e>+<k,h,β,e>才能正常打开，不能乱点鸳鸯谱。通过只有18种模式，每种模式可以从最大算子连续变化到最小算子，已经证明了没有一个命题算子被遗漏。