Increasing the efficiency of bladeless fans by applying longitudinal cylindrical grooves on the diffuser walls

Relevance Today, there is a growing demand for the unmanned aerial vehicles usage to solve various types of problems. Moreover, unmanned aerial vehicles often designed and manufactured using standard imported components. The creation of electric unmanned aerial vehicles is promising, due to their environmental friendliness and reliability. Such aircraft are based on electric propulsion systems — electrotechnical complexes and systems consisting of an electric motor, an inverter electronic unit and a propeller. Aircraft type electric unmanned aerial vehicles are widespread due to their high range and flight time. Electric motors of aircraft type unmanned aerial vehicles are subject to increased requirements for noise and vibration levels, since the body of aircraft-type unmanned aerial vehicles can act as a resonator. As part of programs to ensure import independence of the Russian Federation, the development and research of electric motors for propulsion systems of electric unmanned aerial vehicles, including aircraft types, are relevant. Aims of research The main aim of the research is to determine the current technical and scientific level of developments in the field of electric motors for unmanned aerial vehicles. Identification of features and trends in research and development in the field of electric motors for unmanned aerial vehicles. Design, manufacture of experimental samples and research a brushless permanent magnet electric motor for unmanned aerial vehicles. Identifying a series of works aimed at developing a methodology for the design and research of electric motors for propulsion systems of unmanned aerial vehicles. Research methods During the design, methods of analytical calculation and computer finite element modeling were used. Experimental research methods were used to validate computer models and determine whether the created electric motor met the required parameters. To conduct experimental studies, a special stand was used with the ability to measure the thrust of the propulsion system. In the future, it is planned to use 3D scanning methods and restore the geometry of propellers for coupled models. Results As a result of the work carried out, an electric motor for aircraft-type unmanned aerial vehicles was developed and researched. Features that must be considered during design were identified. Several works have been identified that will be carried out as part of the design and research of electric motors for unmanned aerial vehicles, aimed at creating a new high-precision interdisciplinary design methodology. The work carried out is the basis for the development of new and scientific approaches to the creation of electric propulsion systems for unmanned aerial vehicles.

Currently, such expert systems that are used in the “pilot advisor” mode are widely used in manned aircraft. The main task that these systems allow to solve is that it becomes possible to formulate recommendations when the pilot has an acute lack of time to make appropriate decisions. Manned aircraft are being replaced by unmanned aerial vehicles, which entails changes in the intelligent navigation and control system of such aircraft. The main feature of the corresponding intelligent navigation and control system is the objective need for the formation and implementation of solutions with minimal involvement of personnel of the corresponding unmanned aerial system. The article discusses the structure and model of an on-board expert control system for a promising unmanned aerial vehicle. The structure of the interaction of the proposed promising on-board expert control system for an unmanned aerial vehicle with sources of initial data and consumers of the formed control solutions is presented. The main issues of the organization’s work on the formation of the goals of the on-board expert management system are considered. The main issues of operation of an on-board expert control system of a promising unmanned aerial vehicle are considered.

On parallel hybrid-electric propulsion system for unmanned aerial vehicles

The article describes the results of the experimental study on the influence of operator’s activities on the control system of a heterogeneous unmanned aerial vehicles’ group. The proposed mathematical apparatus allows to present the actions of the operator as part of the automated control system, to carry out a quantitative assessment of the efficiency of the operator’s actions. It also allows to evaluate the impact of the results of this activity on the effectiveness of solving tasks in the control system of an unmanned aerial vehicles’ group. The given experimental data and obtained laws of distribution of various random variables can be used in modelling the activity of the operator in complex control systems of an unmanned aerial vehicles’ group. Management of operators’ activity models enables to improve the quality of the development of decision support system.

This paper presents the identification process of the electric propulsion system for Unmanned Aerial Vehicles. Prepared identification test rig was described in details. It allows to control the electric motor with a propeller and to measure the parameters like thrust force, torque, current and supply voltage, that were used during identification. The worked out and presented identification test helps to check and verify the electric propulsion properties and to develop more accurate simulation models of UAVs.

Bladeless fans are well known for their unique shape and efficient performance, which have a great impact on the fan industry. At present, there are few studies on the bladeless fan and the research on the improvement of fan design is a lack. Therefore, the study on the performance of the bladeless fan with different design is the main purpose of this thesis. In the present study, a bladeless fan prototype is created and studied by numerical simulations. When characterizing the aerodynamic and aeroacoustic performances of the bladeless fan, the entire fan prototype, including wind channel, base, rotor and stator, is adopted; when investigating the influence of the wind channel's geometric parameters, only wind channel is considered in simulations. The influence of the slit width, the height of the cross-section, the slit location and the profile of the cross-section are studied. It is found that the flow outside the bladeless fan consists of the air blown out from the wind channel and entrained from the back and side of the fan. The air entrained from the side is the main source of flow rate increase. As for the aeroacoustic performance, the rotor and stator inside the base are the predominated source of the noise generated by the bladeless fan. The performances of the bladeless fan are very sensitive to the geometric details of the wind channel. The generated noise always increases as the wind strength improves. The slit width of the wind channel has the greatest impact. With the slit moves away from the leading edge, the wind produced by the bladeless fan becomes more powerful and the noise becomes louder. The cross-sectional height of 4cm has the best aerodynamic performance but the generated noise is a little larger than other designs. The profile of the cross-section shows insignificant influence on the performances.

Abstract. The collection and updating of 3D data is the one of the important steps for GIS applications which require fast and efficient data collection methods. The photogrammetry has been used for many years as a data collection method for GIS application in larger areas. The Unmanned Aerial Vehicles (UAV) Systems gained increasing attraction in geosciences for cost effective data capture and updating at high spatial and temporal resolution during the last years. These autonomously flying UAV systems are usually equipped with different sensors such as GPS receiver, microcomputers, gyroscopes and miniaturized sensor systems for navigation, positioning, and mapping purposes. The UAV systems can be used for data collection for digital elevation model DEM and orthoimages generation in GIS application at small areas. In this study, data collection and processing by light UAV system will be evaluated for GIS data capture and updating for small areas where not feasible for traditional photogrammetry. The main aim of this study is to design the low cost light UAV system for GIS data capture and update. The investigation was based on the aerial images which recorded during the flights performed with UAV system over the test site in Davutpasa Campus of Yildiz Technical University, Istanbul. The quality of generated DEM and ortho-images from UAV flights was discussed for GIS data capture and updating for small areas.

A Model for Assessing UAV System Architectures

System for unmanned aerial vehicles (UAV) advanced alternative energy (SAvE) is a research project funded in 2007 by Piemonte Regional Government, Italy, and assigned to Politecnico di Torino and Alenia Aeronautica. Aim of the project is the study of new, more efficient, more effective, and more environmentally friendly on board systems for future advanced UAV, particularly for future advanced medium altitude long endurance (MALE) UAVs. This article deals with the analysis and design of the all electric secondary power system of a future advanced MALE UAV that is considered as ‘reference aircraft’. After a thorough trade-off analysis of different configurations of the secondary power system, the hybrid fuel cells configuration, characterized by starter/generators, fuel cells, and traditional and innovative batteries, has been selected as the most promising. Detailed investigations to find the best way to apportion the supply of secondary power, considering the various power sources (starter/generators, batteries, and fuel cells) in the different modes of operations, have been performed thanks to an integrated simulation environment, where physical, functional, and mission scenario simulations continuously exchange data and results.

This paper proposes the design and development of an on-board autonomous visual tracking system (AVTS) for unmanned aerial vehicles (UAV). A prototype of the proposed system has been implemented in MATLAB/ Simulink for simulation purposes. The proposed system contains GPS/INS sensors, a gimbaled camera, a multi-level autonomous visual tracking algorithm, a ground stationary target (GST) or ground moving target (GMT) state estimator, a camera control algorithm, a UAV guidance algorithm, and an autopilot. The on-board multi-level autonomous visual tracking algorithm acquires the video frames from the on-board camera and calculates the GMT pixel position in the video frame. The on-board GMT state estimator receives the GMT pixel position from the multi-level autonomous visual tracking algorithm and estimates the current position and velocity of the GMT with respect to the UAV. The on-board non-linear UAV guidance law computes the UAV heading velocity rates and sends them to the autopilot to steer the UAV in the desired path. The on-board camera control law computes the control command and sends it to the camera's gimbal controller to keep the GMT in the camera's field of view. The UAV guidance law and camera control law have been integrated for continuous tracking of the GMT. The on-board autopilot is used for controlling the UAV trajectory. The simulation of the proposed system was tested with a flight simulator and the UAV's reaction to the GMT was observed. The simulated results prove that the proposed system tracks a GST or GMT effectively.

Autonomous collision avoidance system (ACAS) for Unmanned Aerial Vehicles (UAVs) is set as a tool to prove that they can achieve the equivalent level of safety, required in context of integrating UAVs flight into the National Airspace System (NAS). This paper focus on the cooperative avoidance part, aiming to define an algorithm that can provide avoidance between cooperative UAVs in general, while still be restricted by some common rules. The algorithm is named the Selective Velocity Obstacle (SVO) method, which is an extension of the Velocity Obstacle method. The algorithm gives guidelines for UAVs to select between three basic modes for avoidance, i.e., to Avoid, Maintain, or Restore. The variation of those three modes gives flexibility for UAVs to choose how will they avoid. By modeling the algorithm as a hybrid system, simulations on various UAVs encounters scenario were conducted and shows satisfying result. Monte Carlo simulations are then conducted to conclude the performance even more. Randomizing the initial parameters, including speed, attitude, positions and avoidance starting point, more than 10 encounter scenario were tested, involving up until five UAVs. A parameter called the Violation Probability is then derived, showing zero violations in the entire encounter samples.

This paper presents the design and flight validation of an embedded fiber Bragg gratings (FBG) based structural health monitoring (SHM) system for the Indian unmanned aerial vehicle (UAV), Nishant. The embedding of the sensors was integrated with the manufacturing process, taking into account the trimming of parts and assembly considerations. Reliable flight data were recorded on board the vehicle and analyzed so that deviations from normal structural behaviors could be identified, evaluated and tracked. Based on the data obtained, it was possible to track both the loads and vibration signatures by direct sensors’ cross correlation using principal component analysis (PCA) and artificial neural networks (ANNs). Sensor placement combined with proper ground calibration, enabled the distinction between strain and temperature readings. The start of a minor local structural temporary instability was identified during landing, proving the value of such continuous structural airworthy assessment for UAV structures.

In this study, a robust <inline-formula> <tex-math notation="LaTeX">$H_{\infty }$ </tex-math></inline-formula> networked security observer-based reference tracking control scheme is proposed for the stochastic quadrotor unmanned aerial vehicle (UAV) system under malicious attacks on the actuator and sensor of network control system (NCS). To reduce the computational burden on UAV system, the UAV system is connected with a remote computing unit and the complicated tracking control command can be calculated by remote computing unit. By using the novel discrete smoothed model, the model of attack signals on actuator and sensor can be embedded in system state of UAV and thus the attack signals as well as the quadrotor system state can be simultaneously estimated through a conventional Luenberger observer. Further, the corruption of attack signals on state estimation of UAV is also avoided. To eliminate the effect of unavailable external disturbance and intrinsic fluctuation during the reference tracking control process, a robust <inline-formula> <tex-math notation="LaTeX">$H_{\infty }$ </tex-math></inline-formula> networked security observer-based reference tracking control scheme is introduced to attenuate their effects on the NCS of quadrotor UAV. By using the characteristic of convex Lyapunov function, the design condition of robust <inline-formula> <tex-math notation="LaTeX">$H_{\infty }$ </tex-math></inline-formula> networked security observer-based tracking control is derived in terms of the nonlinear functional inequalities. Since the nonlinear functional inequalities are not easy to be solved analytically or numerically, the Takagi-Sugeno (T-S) fuzzy interpolation technique is employed to interpolate the nonlinear stochastic quadrotor NCS by a set of linear local systems via fuzzy bases. In this case, the nonlinear functional inequalities can be converted to a set of linear matrix inequalities (LMIs) which can be easily solved by the MATLAB LMI TOOLBOX. Simulation results are provided to validate the effectiveness of the proposed method in comparison with conventional robust observer-based T-S fuzzy tracking control scheme.

Abstract. Based on the characteristics of Unmanned Aerial Vehicle (UAV) system for low altitude aerial photogrammetry and the need of three dimensional (3D)city modeling, a method of fast 3D building modeling using the images from UAV carrying four-combined camera is studied. Firstly, by contrasting and analyzing the mosaic structures of the existing four-combined cameras, a new type of four-combined camera with special design of overlap images is designed, which improves the self-calibration function to achieve the high precision imaging by automatically eliminating the error of machinery deformation and the time lag with every exposure, and further reduce the weight of the imaging system. Secondly, several-angle images including vertical images and oblique images gotten by the UAV system are used for the detail measure of building surfaces and the texture extraction. Finally, two tests that are aerial photography with large scale mapping of 1:1000 and 3D building construction in Shandong University of Science and Technology and aerial photography with large scale mapping of 1:500 and 3D building construction in Henan University of Urban Construction, provide authentication model for construction of 3D building based on combined wide-angle camera images from UAV system. It is demonstrated that the UAV system for low altitude aerial photogrammetry can be used in the construction of 3D building production, and the technology solution in this paper offers a new, fast and technical plan for the 3D expression of the city landscape, fine modeling and visualization.

In this study, we examined the robust super-twisting sliding mode backstepping control (SBSC) method, which employed a tracking differentiator and nonlinear disturbance observer for a hexacopter unmanned aerial vehicle (UAV) system. To realize robust tracking control performance for a highly coupled nonlinear hexacopter UAV system, a super-twisting sliding mode control method was combined with designing stabilizing controls of backstepping control (BSC) applied to the UAV system. Furthermore, the differentiation issue of the virtual control and compensation of transformation error in the conventional BSC design were bypassed via a new continuous tracking differentiator structure. Additionally, a new disturbance observer based on the proposed tracking differentiator was considered to estimate uncertainties of the hexacopter UAV. Comparative simulation results demonstrated that the proposed tracking-differentiator-based SBSC scheme (PTSBSC) blended with the tracking differentiator and nonlinear disturbance observer exhibits improved performance when compared to that of conventional BSC and disturbance observer systems.