Modeling and Experimental Validation of Underactuated Rotor Dynamics for Swashplate-less UAVs

This paper presents the design and implementation of leaping control methods for replicating high-speed dolphin leaping behavior. With full consideration of both mechanical configuration and propulsive principle of a physical robot comprising one neck joint, two propulsive joints, and a pair of two-degrees-of-freedom (2-DOF) mechanical flippers, closed-loop pitch, roll, yaw, and depth control methods are integrated to accomplish precise attitude control. Specifically, two pitch control strategies are proposed to separately satisfy small and large pitch requirements based on the real-time feedback of the pitch angle, while the roll controller is further implemented as a proportional-integral-derivative (PID) loop. A combination of pitch and roll control is utilized to regulate the desired pitch maneuvers. Finally, a parameterized five-phase leaping control algorithm instead of Weihs's three-phase porpoising model is implemented on the self-contained real robot, enabling the examination of biological leaping phenomena which are hard to observe or measure. Latest experimental results reveal that besides high speeds exceeding the minimum exit speeds, the pitch control closely related to pitch angle and submersion depth is another critical factor contributing to effective dolphin leaping.

URLLC in UAV-enabled multicasting systems: A dual time and energy minimization problem using UAV speed, altitude and beamwidth

This paper describes the development of a simple, low-cost, embedded auto pilot for an Unmanned Aerial Vehicle (UAV) and its integration to achieve self-flight capability using commercially available off-the shelf modules and components. The autopilot was developed using Arduino Mega 2560 embedded micro-controller platform and integrated with a DJI Spreading Wings S800 Hexa-copter platform, Wookong M Flight Stabilization Controller, and Sensors. A Ground Control Station (GCS) and a wireless communication system to communicate with the UAV was developed using Xbee modules and tested for realtime communication. GCS sends remote control commands, way-points and navigation plan to the on-board autopilot and receives data streams from the UAV. MATLAB was used for creating the Graphical User Interfaces (GUI) for communication. It is capable of sending commands to the micro-controller and receiving data and state information from the UAV in near-real time and was successfully used for tuning the autopilot. Autopilot development and integration was carried out in two stages: (1) Experiments for estimating the physical parameters and manually tuning the Thrust, Roll, Pitch and Yaw Control parameters using a RC-controller. (2) Coupling the Auto pilot (integrating the Arduino Mega 2560 embedded micro-controller) to the Platform and tuning Roll, Pitch, Yaw and thrust control for stable control manoeuvres. We also discuss some integration issues and report the results.

This report introduces 3 post-processing techniques that can be used on images captured from an unmanned aerial vehicle (UAV) to distort the images in such a way as to make all the images appear as though they were taken from a uniform altitude, pitch, roll and yaw and from a rectilinear lens, meaning that when the images are stitched together the resulting map is accurate. The recent increase in demand for UAV technologies in the marketplace has been illustrated by a host of new products from major companies. The work in this report adds to the field of imaging from UAV's — for example, the creation of an aerial map. A current limitation in technology is the distortion of images captured by UAVs. This distortion is caused by turbulence as well as the necessary pitch and roll rotations required to move horizontally. This report introduces techniques which make images captured from fisheye lenses appear rectilinear; make all images appear of uniform scale, regardless of the height at which they were captured; and correct for any skew distortions caused by the pitch, roll and yaw of the UAV. All algorithms were developed in Matlab and tested on actual UAV images. This report focuses on rotary wing UAV's such as quad-copters and hexa-copters, although some of the principles discussed could be applied to fixed-wing aircraft as well.

Energy optimization for full-duplex wireless-powered IoT networks using rotary-wing UAV with multiple antennas

In this study, we generated Digital Elevation Model (DEM) from Unmanned Aerial Vehicle (UAV) to confirm the suitability of UAV to the tidal flat study. The DEMs were generated from aerial triangulation method using rotary-wing UAV. For the accurate generation of mosaic images and DEM, the distorted images occurred by interior and exterior orientation were corrected using camera calibration. In addition, we set up a Ground Control Points (GCPs) in order to correct of the UAV position error. Therefore, the DEM was obtained with geometric error less than 30 cm. The height of generated DEM by UAV was compared with the levelled elevation by RTK-GPS and TanDEM-X radar satellite DEM. From this study, we could confirm that accurate DEM of the tidal flat can be generated using UAV and these detailed spatial information about tidal flat will be widely used for tidal flat management.

Topoloji optimizasyonu kullanılarak gerçekleştirilen hafif yapı tasarımları kütle özelliklerinden dolayı havacılık sektöründe ilgi görmektedir. Bu konuyla ilgili olarak yapılan çalışmalar incelendiğinde dayanım özellikleri değiştirilmeden yapı kütlesinin azaltılmasının hedeflendiği görülmektedir. Hava aracı çeşitlerinden biri olan ve kendine özgü uçuş özelliklerine sahip olmasından ötürü havacılık sektöründe kullanım alanı giderek artan döner kanatlı insansız hava araçlarının tasarımında yapı kütlesini azaltmak amacıyla topoloji optimizasyonu yöntemleri kullanılmaktadır. Bu yöntemlerin uygulanması sayesinde döner kanatlı insansız hava araçlarının dayanım-ağırlık oranı ve verimi artmaktadır. Bu çalışmada, döner kanatlı insansız hava araçlarının topoloji optimizasyonu konusunda literatürde bulunan çalışmalar araştırılmış ve elde edilen sonuçlar sunulmuştur. Yapılan araştırma sonucunda topoloji optimizasyonu yöntemlerinin hava aracı tasarımında yapı ağırlığını, yapı gerilimini ve kuvvete maruz kalan yapıdaki yer değiştirme değerini etkilediği tespit edilmiştir. Literatürdeki çalışmalarda araştırmacılar tarafından birim hücre yapısı içeren optimizasyon teknikleri ve birim hücre yapısı içermeyen optimizasyon teknikleri olmak üzere iki farklı strateji kullanıldığı görülmüştür.

This paper considers unmanned aerial vehicle (UAV)-assisted infrastructure-to-vehicle (I2V) communication employing UAVs as relays to increase the throughput between a roadside unit (RSU) and a vehicular user equipment (VUE). We investigate the UAV position planning problem under both single UAV and multiple cooperative UAVs scenarios while considering the mobility of the VUE, aiming to maximize the data rate of the system. We first consider using a single UAV and prove that the single UAV position planning can be formulated as a convex optimization problem, and then obtain the optimal position of the UAV. Next, we investigate the multiple cooperative UAVs scenario and formulate the joint power control and position planning problem to improve the data rate of the system under a fixed total power consumption. Numerical simulations are provided to verify our theoretical results. Our findings highlight the effects of important system parameters, such as height, transmit power, and the number of UAVs, on the optimal UAV positioning and system performance.

This study confirms the feasibility of the logistics system by unmanned aerial vehicle (UAV) with 28GHz microwave power transmission (MPT). 28GHz MPT with the retrodirective system toward for autonomous flight UAV is carried out. The result shows that maximum DC output power is 47.5mW at 80cm from the ground and the peak value is 89% of the value which rectennas are fixed. As results of the experiment, if six transmitters radiated 182kW are built equidistantly, 100km flight without landing takes 2 hours. This is 10 times more effective than 5.8GHz MPT. Thus, this study shows 28GHz MPT is the advantage over 5.8GHz MPT for the logistics system by UAV.

In this paper, a new roll and pitch control mechanism for an underwater glider is described. The mechanism controls the glider’s pitch and roll without the use of a conventional buoyancy engine or movable mass. The mechanism uses water as trim mass, with a high flow rate water pump to shift water from water bladders located at the front, rear, left, and right of the glider. By shifting water from the left water bladder to the right water bladder, a roll moment is induced. Similarly, pitch is achieved by controlling the water flow between the front and rear water bladder using a water pump. The water bladders act not only as a means for roll and pitch control but as a buoyancy engine as well. While this mechanism reduces the need for a dedicated buoyancy engine, as well as internal moving masses, motion control is more complicated, as buoyancy, roll, and pitch must be considered simultaneously. The dynamics of the system were derived and simulated, as well as validated experimentally. The glider is able to move in a sawtooth pattern with a pitch angle of 43.5?, as well as a maximum roll angle of 43.6?. Additionally, the effect of pump rate on pitch and roll rate was investigated. Both pitch and roll rates increase with increasing pump rate.

Information acquisition and rescue operation management can be facilitated by the use of unmanned aerial vehicles (UAVs) equipped with cameras and sensors that are capable of aerial photography and acquire important information from disaster-stricken areas. UAV technology is a relatively low-cost, flexible, and safe solution in missions that are difficult for humans or other systems. UAV usage in pre-and post-disaster assessment, response, and management is an active area of research. There are two important technical aspects of UAV applications in disaster situations. The first is the limited communication range. Information acquired and photography produced by UAVs are only transmitted in real-time to the ground control station (GCS) within its communication range. Remote real-time monitoring of distant areas beyond the UAV's communication range is not possible using a single UAV. It is only possible through communication among several UAVs. The second is the relatively short flight time due to limited battery capacity. UAV replacement is required in order to carry out a persistent monitoring mission. In this paper, we propose a new remote real-time monitoring system of a distant disaster area using multiple UAVs. Wireless communications between multiple UAVs constitutes a UAV network in our proposed system. Moreover, the proposed system replaces the UAVs in-flight with standby UAVs according to the remaining energy levels. We compare the performance of the proposed system with an existing UAV system. Our simulation results show that the proposed system can achieve efficient remote real-time monitoring.

The integration of unmanned aerial vehicles (UAVs) with wireless communication systems greatly enhances the application area of intelligent transportation systems (ITS). One of the mission-critical applications enabled by these systems is disaster management, where communication functionality can provide users with supplementary information such as escape routes, time to rescue, etc. In this paper, considering a large area with several locations of interest, we formulate and solve the optimization problem of delivering critical information by optimizing the UAV speed and the order of visits to the locations of interest so that the mission time is minimized. The formulated problem is a mixed integer nonlinear program, which is quite challenging to solve. To reduce the complexity of solution algorithms, we propose two circular trajectory designs. The first algorithm finds the optimal velocity and radius of the circular trajectories of the UAV. The second algorithm finds the optimal connections to join the individual circular trajectories. An important practical benefit of using circular trajectory design is that it can be implemented through either fixed-wing or rotary-wing UAVs. Our numerical results reveal that, with practical simulation parameters, the proposed single circular trajectory design provides a time saving of at least 30% as compared to existing zigzag trajectory design. Moreover, the proposed multiple circular trajectory design cuts the total mission completion time by at least 7 times as compared to proposed single circular trajectory design.

Search and Rescue (SAR) is an operation conducted to find and return to safety the survivors of an emergency incident, where the search may have to be conducted in difficult areas such as in mountains, deserts, forests or at sea. Maritime SAR operations normally involve a large number of vessels and possibly helicopters as well, but this has been found not to be effective enough. This paper looks at Unmanned Aerial Vehicles (UAVs) to assist in maritime SAR operations, leaning towards rotary wing UAVs with the capabilities of flying vertically and horizontally as well as hover at required positions for close monitoring. The focus is on the algorithm for determining the exact position of the target subject(s).

Unmanned aerial vehicles (UAV) have been widely used in many fields. UAV formation flight can complete more assignments than single UAV. Collision avoidance is an important part of UAV formation flight. In this paper, we put forward a three-dimensional method of dynamic collision avoidance for UAV formation flight based on the theory of velocity obstacle. The collection of all possible accelerations of the UAV can be obtained by the input of UAV. Considering that the relative velocity between the UAV and obstacle must be out of the collision cone, we can obtain the collection of feasible accelerations next moment. Then we choose the acceleration which is able to let the UAV closest to the target next moment in the collection as the real acceleration. The maximum and minimum velocity should also be set up. Each UAV can determine the best acceleration next time for itself. In addition to formation keeping, this paper also presents how to split the formation on the basis of the direction of each UAV. Numerical simulation is used to test the performance of this method at the end of this paper.

Cellular-enabled unmanned aerial vehicles (UAVs) require almost continuous cellular network connectivity to fulfill their missions successfully. However, the area (e.g., rural) they fly over may have partial coverage, making the path planning of such UAV missions a challenging task. Recently a tolerable outage duration is taken into account for such UAVs, and the trajectory optimization under this outage duration is studied. However, these existing studies consider only a single UAV and focus on optimization of each UAV's own path separately even in multi-UAV scenarios. In this paper, we study the trajectory optimization problem for cellular-enabled UAVs by taking into account the collaboration among UAVs. That is, for a given set of UAVs, each with a mission to fly from a starting point to an ending point, we aim to optimize the total mission completion time for all UAVs such that none of them has a connection outage more than a threshold. We let UAVs collaborate and provide connectivity as relays to each other to solve their outage problem and shorten their trajectories. We first model and solve this problem using nonlinear programming after discretization of the problem. Since it takes longer to solve the problem with such an approach, we then provide a graph-based approximate solution that runs fast. Numerical results show that the proposed approximate solution provides close to optimal results and performs better than state-of-the-art solutions that consider each UAV separately without collaboration among UAVs.