Search Results (4)

Aircraft and fixed-wing drones, designed to perform vertical take-off and landing (VTOL), often incorporate unconventional configurations that offer unique capabilities but simultaneously pose significant challenges in flight mechanics modeling, whose reliability strongly depends on the correct tuning of the inertial and aerodynamic parameters. Having a good characterization of the aerodynamics represents a critical issue, especially in the design and optimization of unconventional aircraft configurations, when, indeed, one is bound to employ empirical or semi-empirical methods, devised for conventional geometries, that struggle to capture complex aerodynamic interactions. Alternatives such as high-fidelity computational fluid dynamics (CFD) simulations, although more accurate, are typically expensive and impractical for both preliminary design and lofting optimization. This work introduces a procedure that exploits multiple analyses conducted through semi-empirical methodologies implemented in the USAF Digital DATCOM to develop a flight mechanics model for fixed-wing unmanned aerial vehicles (UAVs). The reference UAV chosen to test the proposed procedure is the Dragonfly DS-1, an electric VTOL UAV developed by Overspace Aviation, featuring a three-surface configuration. The accuracy of the polar data, i.e., the lift and drag coefficients, is assessed through comparisons with computational fluid dynamics simulations and flight data. The main discrepancies are found in the drag estimation. The present work represents a preliminary investigation into the possible extension of semi-empirical methods, consolidated for traditional configurations, to unconventional aircraft so as to support early-stage UAV design. Full article

Accurate tracking and predicting unmanned aerial vehicle (UAV) trajectories are essential to ensure mission success, equipment safety, and data accuracy. Maneuverable UAVs exhibit complex and dynamic motion, and conventional tracking algorithms that rely on predefined models perform poorly when unknown parameters are used. To address this issue, this paper introduces a hybrid dual-scale neural network model based on the generalized regression multi-model and cubature information filter (GRMM-CIF) framework. We have established the GRMM-CIF filtering structure to differentiate motion modes and reduce measurement noise. Furthermore, considering trajectory datasets and rates of motion change, a neural network at different scales will be designed. We propose the dual-scale bidirectional long short-term memory (DS-Bi-LSTM) algorithm to address prediction delays in a multi-model context. Additionally, we employ scale sliding windows and threshold-based decision-making to achieve dual-scale trajectory reconstruction, ultimately enhancing tracking accuracy. Simulation results confirm the effectiveness of our approach in handling the uncertainty of UAV motion and achieving precise estimations. Full article

A greenhouse is used to improve thermal comfort (TC) levels for its occupants in winter conditions using solar radiation, which involves low energy consumption. The aim of this research is the application of unmanned aerial vehicles (UAVs) in the evaluation of thermal comfort levels in buildings equipped with internal greenhouses. The new building design is developed numerically, and a building thermal simulator (BTS) numerical model calculates the indoor environmental variables. A new alternative and expeditious method to measure occupants’ comfort levels using UAV technology is applied using a UAV dynamic simulator (UAV DS). The evolution of the measured variables used for evaluating the predicted mean vote (PMV) is compared using the two numerical methodologies: BTS and UAV DS. In the second one, the mean radiant temperature (MRT) measuring methodology, the floor temperature, the lateral walls’ temperatures, the ceiling temperatures, and the air temperature are applied. In the method presented in this paper, a new building design is developed numerically, which includes a central greenhouse equipped with a semispherical dome, four auditoriums distributed around the central greenhouse, occupant distribution, and a ventilation methodology. The building geometry, the solar radiation on transparent surfaces, the TC, and the UAV mission methods are presented. The results show that, in general, the central greenhouse and the ventilation methodologies provide acceptable TC levels. The UAV monitoring mission, which includes two vehicles, provides good environmental variable replication, particularly when the environmental variables present greater variations. In the auditorium and greenhouse, the ceiling and lateral surface temperatures, respectively, can be used as an MRT approximation. The BTS numerical model is also important for developing buildings using renewable energy sources to improve the TC levels. Full article

Three-dimensional (3D) modeling of tsunami events is intended to promote tsunami safety. However, the developed 3D modeling methods based on Computational Fluid Dynamics and photorealistic particle visualization have some weaknesses, such as not being similar to the original environment, not measuring the wave’s end point, and low image accuracy. The method for 3D modeling of tsunamis that results from this research can fulfil those weaknesses because it has advantages, such as being able to predict the end point of waves, similar to the original environment, and the height and area of inundation. In addition, the method produces more detailed and sharper spatial data. Modeling in this research is conducted using Agisoft Metashape Professional software to a produce 3D orthomosaic from pictures taken with Unmanned Aerial Vehicle (UAV) technique or drone (photogrammetry), and 3ds max software is used for wave simulation. We take a sample of an area in Cilacap, Indonesia that was impacted by the 2006 southwest coast tsunamis and may be vulnerable to future big megathrust earthquakes and tsunamis. The results could be used to provide several benefits, such as the creation of evacuation routes and the determination of appropriate locations for building shelters. Full article