Three-dimensional Flight Research Articles

Signatures of a globally optimal searching strategy in the three-dimensional foraging flights of bumblebees.

Simulated annealing is a powerful stochastic search algorithm for locating a global maximum that is hidden among many poorer local maxima in a search space. It is frequently implemented in computers working on complex optimization problems but until now has not been directly observed in nature as a searching strategy adopted by foraging animals. We analysed high-speed video recordings of the three-dimensional searching flights of bumblebees (Bombus terrestris) made in the presence of large or small artificial flowers within a 0.5 m3 enclosed arena. Analyses of the three-dimensional flight patterns in both conditions reveal signatures of simulated annealing searches. After leaving a flower, bees tend to scan back-and forth past that flower before making prospecting flights (loops), whose length increases over time. The search pattern becomes gradually more expansive and culminates when another rewarding flower is found. Bees then scan back and forth in the vicinity of the newly discovered flower and the process repeats. This looping search pattern, in which flight step lengths are typically power-law distributed, provides a relatively simple yet highly efficient strategy for pollinators such as bees to find best quality resources in complex environments made of multiple ephemeral feeding sites with nutritionally variable rewards.

Path planning for UAV under three-dimensional real terrain in rescue mission

Basing on the capability of three-dimensional flight and planning of optimal path,unmanned aerial vehicles( UAVs) can reach the disaster areas within shorter time than ground vehicles,which will improve the efficiency of rescue. Firstly,according to the real geographical environment,terrain is modeled by a mesh uniform method based on UAV constraints. Secondly,a data structure which is suitable for calculation is designed based on the characteristics of terrain data. Finally,the integrative performance function includes the deviation cost,height cost,terrain following / avoidance cost,threat cost and security distance cost. Both methods of waypoints cross and grid search instead of waypoints are engaged in the improved ant colony algorithm to make three-dimensional UAV path planning. The simulation results show that the method can deal with three-dimensional terrain data directly. While maintaining the topography of the premise,it can find the three-dimensional optimal path of UAV and improve the practical value of path planning technology.

Field Flight Dynamics of Hummingbirds during Territory Encroachment and Defense.

Hummingbirds are known to defend food resources such as nectar sources from encroachment by competitors (including conspecifics). These competitive intraspecific interactions provide an opportunity to quantify the biomechanics of hummingbird flight performance during ecologically relevant natural behavior. We recorded the three-dimensional flight trajectories of Ruby-throated Hummingbirds defending, being chased from and freely departing from a feeder. These trajectories allowed us to compare natural flight performance to earlier laboratory measurements of maximum flight speed, aerodynamic force generation and power estimates. During field observation, hummingbirds rarely approached the maximal flight speeds previously reported from wind tunnel tests and never did so during level flight. However, the accelerations and rates of change in kinetic and potential energy we recorded indicate that these hummingbirds likely operated near the maximum of their flight force and metabolic power capabilities during these competitive interactions. Furthermore, although birds departing from the feeder while chased did so faster than freely-departing birds, these speed gains were accomplished by modulating kinetic and potential energy gains (or losses) rather than increasing overall power output, essentially trading altitude for speed during their evasive maneuver. Finally, the trajectories of defending birds were directed toward the position of the encroaching bird rather than the feeder.

Mission Performance Simulation of Integrated Helicopter–Engine Systems Using an Aeroelastic Rotor Model

This paper presents an integrated approach, targeting the comprehensive assessment of combined helicopter engine designs within designated operations. The developed methodology comprises a series of individual modeling theories, each applicable to a different aspect of helicopter flight dynamics and performance. These relate to rotor blade modal analysis, three-dimensional flight path definition, flight dynamics trim solution, aeroelasticity, and engine performance. The individual mathematical models are elaborately integrated within a numerical procedure, solving for the total mission fuel consumption. The overall simulation framework is applied to the performance analysis of the Aérospatiale SA330 helicopter within two generic, twin-engine medium helicopter missions. An extensive comparison with flight test data on main rotor trim controls, power requirements, and unsteady blade structural loads is presented. It is shown that, for the typical range of operating conditions encountered by modern twin-engine medium civil helicopters, the effect of operational altitude on fuel consumption is predominantly influenced by the corresponding effects induced on the engine rather than on airframe rotor performance. The implications associated with the implicit coupling between aircraft and engine performance are discussed in the context of mission analysis. The potential to comprehensively evaluate integrated helicopter engine systems within complete three-dimensional operations using modeling fidelity designated for main rotor design applications is demonstrated. The proposed method essentially constitutes an enabler in terms of focusing the rotorcraft design process on designated operation types rather than on specific sets of flight conditions.

Terminal control of aircraft motion

A method for the construction of the three-dimensional flight trajectory and calculation of the corresponding controls is described for the terminal control problem of aircraft motion. The solution uses a six-dimensional mathematical model with the controls modeled by the coordinates of the load vector. The proposed method is demonstrated with specific examples.

Integration of image de-blurring in an aerial Mono-SLAM

In this article, we discuss the possibility of integrating image de-blurring techniques in an aerial simultaneous localization and mapping by a single camera (monocular simultaneous localization and mapping (Mono-SLAM)). We use an integrated aerial virtual environment together with a six-degree-of-freedom aircraft flight simulator to show the effectiveness of the approach to generate three-dimensional flight trajectories via integration of image de-blurring in the associated loop of the Mono-SLAM. The objective is to increase the overall performance of a flying mission over an unknown area by means of a vision-only method. The integrated aerial virtual environment produces and collects real-time pictures from a nadir-looking vision sensor mounted on the vehicle. Our MATLAB GUI-based toolbox helps user to investigate an offline Mono-SLAM with a predefined de-blurring method integrated with an estimator which extracts navigational parameters. The system efficient architecture allows effective virtual experiments in a completely unknown environment, without using preloaded maps or predefined features. Simulation outcomes demonstrate the feasibility of navigation of aerial robots in inaccessible environments. Different case studies support the conclusion; nonetheless, we observe a number of nonlinearities from de-blurring filters even for a general aviation aircraft.

The strange flight behaviour of slowly spinning soccer balls

The strange three-dimensional flight behaviour of slowly spinning soccer balls is one of the most interesting and unknown phenomenon associated with the trajectories of sports balls. Many spectators have experienced numerous exciting and emotional instances while observing the curious flight behaviour of these balls. We examine the aerodynamic mechanisms of erratic ball behaviours through real flight observations, unsteady force measurements and flow pattern visualisations. The strange behaviour is elucidated by the relationship between the unsteady forces on the ball and the wake flow. The irregular changes in position for twin longitudinal vortices have already been discovered in the supercritical Reynolds number region of a sphere with a smooth surface. This finding is applicable to the strange behaviour of the flight of soccer balls with this supercritical flow. The players, spectators, and television viewers will gain greater insight into the effects of soccer ball flights.

Comparison of Adaptive Sampling Methods for Generation of Surrogate Aerodynamic Models

A surrogate modeling strategy, using effective interpolation and sampling methods, facilitates a reduction in the number of computational fluid dynamics simulations required to construct an aerodynamic model to a specified accuracy. In this paper, two adaptive sampling strategies are compared for generating surrogate models, based on Kriging and radial basis function interpolation, respectively. The relationships between the two model formulations are discussed, and three test cases are considered, including analytic functions and recovery of aerodynamic coefficients for two example applications: longitudinal flight mechanics analysis for the DLR-F12 aircraft and structural loads analysis of an RAE2822 airfoil. For the airfoil example, models of , , and were constructed with the two sampling strategies using Euler/boundary-layer-coupled computational fluid dynamics and a three-dimensional flight envelope of incidence, Mach, and Reynolds number. The two sampling approaches direct some samples toward exploration of the domain by minimizing model uncertainty and some toward refinement of local nonlinearities, by adapting to model curvature or extrema. The results provide some evidence that, for certain functions, in certain scenarios, each update scheme could be useful. Both methods were at least better than traditional space-filling sampling for all the test cases presented.

Rolling with the flow: Bumblebees flying in unsteady wakes

Our understanding of how variable wind in natural environments affects flying insects is limited because most studies of insect flight are conducted in either smooth flow or still air conditions. Here, we investigate the effects of structured, unsteady flow (the von Karman vortex street behind a cylinder) on the flight performance of bumblebees (Bombus impatiens). Bumblebees are 'all-weather' foragers and thus frequently experience variable aerial conditions, ranging from fully mixed, turbulent flow to unsteady, structured vortices near objects such as branches and stems. We examined how bumblebee flight performance differs in unsteady versus smooth flow, as well as how the orientation of unsteady flow structures affects their flight performance, by filming bumblebees flying in a wind tunnel under various flow conditions. The three-dimensional flight trajectories and orientations of bumblebees were quantified in each of three flow conditions: (1) smooth flow, (2) the unsteady wake of a vertical cylinder (inducing strong lateral disturbances) and (3) the unsteady wake of a horizontal cylinder (inducing strong vertical disturbances). In both unsteady conditions, bumblebees attenuated the disturbances induced by the wind quite effectively, but still experienced significant translational and rotational fluctuations as compared with flight in smooth flow. Bees appeared to be most sensitive to disturbance along the lateral axis, displaying large lateral accelerations, translations and rolling motions in response to both unsteady flow conditions, regardless of orientation. Bees also displayed the greatest agility around the roll axis, initiating voluntary casting maneuvers and correcting for lateral disturbances mainly through roll in all flow conditions. Both unsteady flow conditions reduced the upstream flight speed of bees, suggesting an increased cost of flight in unsteady flow, with potential implications for foraging patterns and colony energetics in natural, variable wind environments.

Evaluation of Flight Trajectory and Unsteady Fluid Forces on Kicked Non-Spinning Soccer Ball by Digital Image Analysis

This paper describes the experimental method for evaluating the flight trajectory and the aerodynamic performance of a kicked non-spinning soccer ball. The flight trajectory measurement is carried out using the digital image analysis. A centroid method and a template matching method are tested for the flight trajectory analysis using the artificial images generated by the data of a free-fall experiment. The drag coefficient obtained by the centroid method is better suited for the sports ball experiment than that by the template matching method, which is due to the robustness of the centroid method to the non-uniform illumination. Then, the flight trajectory analysis is introduced to a kicked experiment for a non-spinning soccer ball. The experimental result obtained from the stereo observation indicates that the S-shaped variation is found in the three-dimensional flight trajectory and in the side force coefficient during the flight of the non-spinning soccer ball.

Flight Trajectory Visual Simulation Technology of Space-based Reentry Vehicles

This paper is mainly devoted to performing flight trajectory visual simulation of space-based reentry vehicle through the method based on two professional software —MultiGen Creator and Vega Prime. In this approach, scene models and object models are designed with MultiGen Creator. MultiGen Vega Prime is utilized to built movement's models and initial visual simulation environment. The thesis results in constructing a realistic three-dimensional flight virtual environment to simulate flight trajectory of space-based reentry vehicle. According to the approach, characteristics of MultiGen Creator and Vega Prime are investigated, technique conclusions of designing visual models, building simulation environment, performing drive and control of visual simulation are summarized.

The Research of Gray Algorithm and Information Entropy in Route Planning Optimization

In order to solve the Unmanned Aerial Vehicle (UAV) 3-d track planning problems, according to UAV flight are subject to different threats, UAV flight track was established optimal decision-making system, and the fuel consumption, radar threats, missile threats, anti-aircraft threats and atmosphere threats are determined as the evaluation index of objective function, and optimal mathematical model of UAV flight track is constructed. Experience evaluation method is often used to Weight calculation, but there is certain subjectivity .Therefore information entropy method is adopted to determine the Weights by the set of track plans. Grey incidence analysis method is applied to deal with the gray correlation information between the various indicators and to solve the model. Finally, the optimal model is used to scheme selection for flight track planning problem with four threat radar points, five missile threat points, six artillery threat points and four climate threat points to the threat point of flight track planning scheme options. And get the flight track with the best overall performance and Minimum Comprehensive cost, the research provides a theoretical basis for further studying the three-dimensional UAV flight track optimization. DOI: http://dx.doi.org/10.11591/telkomnika.v10i8.1635 Full Text: PDF

Three-dimensional Route Planning for Unmanned Aerial Vehicles in a Risk Environment

This paper introduces a new approach for three-dimensional flight path optimization for unmanned aerial vehicles. It considers the performance of the air vehicle as well as mission specific requirements including the avoidance of no-fly areas, risk reduction in threat environments by terrain following flight or terrain masking low-level flight, and other regulations such as fixed release and approach vectors at the start and destination locations. The focus of the approach is on a proper discretization of the airspace by a network which allows the application of standard algorithms of combinatorial optimization. In contrast to conventional discretizations by grids or grid-like graphs, our network is non-regular since created by some random process. Moreover, each path in the network corresponds to a twice continuously differentiable trajectory which obeys the kinematic restrictions of the air vehicle and which is feasible with respect to the operational requirements of the mission. With suitable costs defined on the edges of the network, a minimum-cost path calculation allows to identify a trajectory of shortest length, shortest flight time, minimum flight height, or minimum visibility from the ground. The latter objectives aim to minimize the probability of being detected by hostile forces, hence increasing the survivability of the air vehicle.

Using three-dimensional flight patterns at airfields to identify hotspots for avian–aircraft collisions

In the United States, black vulture (Coragyps atratus) and turkey vulture (Cathartes aura) pose significant birdstrike risks to aircraft. Understanding flight behaviors of vultures in and around military and civilian airfields is necessary to alleviate these risks. Using satellite telemetry data collected from 11 black vultures and 7 turkey vultures equipped with Global Positioning System backpack harness technology, we collected data on location and altitude near the Marine Corps Air Station (MCAS) in Beaufort, South Carolina from September 2006 to September 2008. We used military aircraft flight landing patterns to visualize a new concept, a flight altitude cone of depression (FACOD), which models a three-dimensional flight pattern over the airfield. We then identified areas in and around MCAS where vulture flight paths penetrated the FACOD and locations of vultures were proximate to flight approach routes that posed potential risk to aircraft for a birdstrike. Combining altitude of in-flight locations of vultures or other species with three-dimensional flight patterns of aircraft provides a novel method for managers of military and domestic airfields to assess birdstrike risk and to focus corrective actions.

The guidance system design of the semi-strapdown homing guided missile

The present paper focuses mainly on the semi-strapdown homing guided system design, which includes control system design of the two-degree-of-freedom semi-strapdown homing seeker and estimation of the guidance information. According to Euler dynamics theory and momentum moment theorem, the two-degree-of-freedom nonlinear dynamic model of the semi-strapdown homing seeker is built in common coordinate frames. Then the control-oriented state-space model of the semi-strapdown homing seeker system is proposed innovatively, and a nonlinear controller is designed by integrating the feedback linearization and linear lead controller. Next, the estimation and construction method of the guidance information based on the unscented Kalman filter is presented for the semi-strapdown homing guided missile. Finally, a three-dimensional interception flight simulation is made using the six-degree-of-freedom axial-symmetry nonlinear aerodynamic model of the semi-strapdown homing guided missile. Simulation results show that guidance information of the semi-strapdown homing guided missile can be estimated via the unscented Kalman filter, and can be used in shaping seeker control command. The seeker nonlinear controller based on feedback linearization can improve the disturbance rejection effect of the semi-strapdown homing seeker effectively with good target tracking ability.

Linking biomechanics and ecology through predator–prey interactions: flight performance of dragonflies and their prey

Aerial predation is a highly complex, three-dimensional flight behavior that affects the individual fitness and population dynamics of both predator and prey. Most studies of predation adopt either an ecological approach in which capture or survival rates are quantified, or a biomechanical approach in which the physical interaction is studied in detail. In the present study, we show that combining these two approaches provides insight into the interaction between hunting dragonflies (Libellula cyanea) and their prey (Drosophila melanogaster) that neither type of study can provide on its own. We performed >2500 predation trials on nine dragonflies housed in an outdoor artificial habitat to identify sources of variability in capture success, and analyzed simultaneous predator-prey flight kinematics from 50 high-speed videos. The ecological approach revealed that capture success is affected by light intensity in some individuals but that prey density explains most of the variability in success rate. The biomechanical approach revealed that fruit flies rarely respond to approaching dragonflies with evasive maneuvers, and are rarely successful when they do. However, flies perform random turns during flight, whose characteristics differ between individuals, and these routine, erratic turns are responsible for more failed predation attempts than evasive maneuvers. By combining the two approaches, we were able to determine that the flies pursued by dragonflies when prey density is low fly more erratically, and that dragonflies are less successful at capturing them. This highlights the importance of considering the behavior of both participants, as well as their biomechanics and ecology, in developing a more integrative understanding of organismal interactions.

Study on Flight Command and Training Simulation System about Aircraft

A scheme of Flight Command and Training Simulation System about Aircraft has been put forward and a prototype has been developed based on the technique of three-dimensional digital terrain elevation, flight simulation and automatic generation of flight route. One can not only study and grasp preliminary knowledge about flight command and training independently with the automatic generation function of flight route of the system, but also can get almost real flight command and training experience when flight mission routes are generated with the fight simulation platform of the system. So the system can meet one’s requirement of learning and grasping flight command and training knowledge very well.

Microphone-Array Tracking of Echolocating Bats Foraging in the Field

Microphone-Array Tracking of Echolocating Bats Foraging in the Field

Design and Attitude Control of a Quad-Rotor Tail-Sitter Vertical Takeoff and Landing Unmanned Aerial Vehicle

In this paper, we present the development of a quad-rotor tail-sitter unmanned aerial vehicle (UAV) that is composed of quad rotors and a fixed wing. The developed UAV can hover like a quad-rotor helicopter and can fly long distance like a fixed-wing airplane. The main wing of the developed UAV is taken from a commercially available radio-controlled airplane and other parts such as the body frame are newly developed. A microcomputer, various sensors and a battery are mounted on the UAV for autonomous flight without any support from a ground system. Attitude and altitude control systems are developed for the UAV. In order to verify the designed controller, a three-dimensional flight simulator of a quad-rotor tail-sitter UAV is developed by use of MATLAB/Simulink. This paper also describes attitude control experiments. The results show that the propeller slipstream has a negative influence on attitude control. Solutions for the negative influence of the propeller slipstream are also discussed in this paper.

How do tiger moths jam bat sonar?

The tiger moth Bertholdia trigona is the only animal in nature known to defend itself by jamming the sonar of its predators - bats. In this study we analyzed the three-dimensional flight paths and echolocation behavior of big brown bats (Eptesicus fuscus) attacking B. trigona in a flight room over seven consecutive nights to determine the acoustic mechanism of the sonar-jamming defense. Three mechanisms have been proposed: (1) the phantom echo hypothesis, which states that bats misinterpret moth clicks as echoes; (2) the ranging interference hypothesis, which states that moth clicks degrade the bats' precision in determining target distance; and (3) the masking hypothesis, which states that moth clicks mask the moth echoes entirely, making the moth temporarily invisible. On nights one and two of the experiment, the bats appeared startled by the clicks; however, on nights three through seven, the bats frequently missed their prey by a distance predicted by the ranging interference hypothesis (∼15-20 cm). Three-dimensional simulations show that bats did not avoid phantom targets, and the bats' ability to track clicking prey contradicts the predictions of the masking hypothesis. The moth clicks also forced the bats to reverse their stereotyped pattern of echolocation emissions during attack, even while bats continued pursuit of the moths. This likely further hinders the bats' ability to track prey. These results have implications for the evolution of sonar jamming in tiger moths, and we suggest evolutionary pathways by which sonar jamming may have evolved from other tiger moth defense mechanisms.