A survey of hybrid Unmanned Aerial Vehicles

This article presents a review on the platform design, dynamic modeling and control of hybrid Unmanned Aerial Vehicles (UAVs). For now, miniature UAVs which have experienced a tremendous development are dominated by two main types, i.e., fixed-wing UAV and Vertical Take-Off and Landing (VTOL) UAV, each of which, however, has its own inherent limitations on such as flexibility, payload, axnd endurance. Enhanced popularity and interest are recently gained by a newer type of UAVs, named hybrid UAV that integrates the beneficial features of both conventional ones. In this paper, a technical overview of the recent advances of the hybrid UAV is presented. More specifically, the hybrid UAV's platform design together with the associated technical details and features are introduced first. Next, the work on hybrid UAV's flight dynamics modeling is then categorized and explained. As for the flight control system design for the hybrid UAV, several flight control strategies implemented are discussed and compared in terms of theory, linearity and implementation.

A review on the platform design, dynamic modeling and control of hybrid UAVs

Additive Manufacturing (AM) is a game changing production technology for aerospace applications. Fused deposition modeling is one of the most widely used AM technologies and recently has gained much attention in the advancement of many products. This paper introduces an extensive review of fused deposition modeling and its application in the development of high performance unmanned aerial vehicles. The process methodology, materials, post processing, and properties of its products are discussed in details. Successful examples of using this technology for making functional, lightweight, and high endurance unmanned aerial vehicles are also highlighted. In addition, major opportunities, limitations, and outlook of fused deposition modeling are also explored. The paper shows that the emerge of fused deposition modeling as a robust technique for unmanned aerial vehicles represents a good opportunity to produce compact, strong, lightweight structures, and functional parts with embedded electronic.

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Fused Deposition Modeling for Unmanned Aerial Vehicles (UAVs): A Review

This paper describes a complete six-degree-of-freedom nonlinear mathematical model of a tilt rotor unmanned aerial vehicle (UAV). The model is specifically tailored for the design of a hover to forward flight and forward flight to hover transition control system. In that respect, the model includes the aerodynamic effect of propeller-induced airstream which is a function of cruise speed, tilt angle and angle of attack. The cross-section area and output velocity of the propeller-induced airstream are calculated with momentum theory. The projected area on the UAV body that is affected by the propeller-induced airstream is specified and 2D aerodynamic analyses are performed for the airfoil profile of this region. Lookup-tables are generated and implemented in the nonlinear mathematical model. In addition, aerodynamic coefficients of the airframe are calculated by using CFD method and these data are embedded into the nonlinear model as a lookup-table form. In the transition flight regime, both aerodynamic and thrust forces act on the UAV body and the superimposed dynamics become very complex. Hence, it is important to define a method for hover-to-cruise and cruise-to-hover transitions. To this end, both transition scenarios are designed and a state-schedule is developed for flight velocity, angle of attack, and thrust levels of each of the thrust-propellers. This transition state schedule is used as a feedforward state for the flight control system. We present the simulation results of the transition control system and show the successful transition of TURAC in experiment.

Transition Flight Modeling of a Fixed-Wing VTOL UAV

Abstract Over the past decade, unmanned aerial vehicles (UAVs) have received a significant attention due to their diverse capabilities for non-combatant and military applications. The primary aim of this study is to unveil a clear categorization overview for more than a decade worth of substantial progress in UAVs. The paper will begin with a general overview of the advancements, followed by an up-to-date explanation of the different mechanical structures and technical elements that have been included. The paper will then explore and examine various vertical take-off and landing (VTOL) configurations, followed by expressing the dynamics, applicable simulation tools and control strategies for a Quadrotor. In conclusion to this review, the dynamic system presented will always face limitations such as internal and/or external disturbances. Hence, this can be minimised by the choice of introducing appropriate control techniques or mechanical enhancements. 

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A Review of Quadrotor Unmanned Aerial Vehicles: Applications, Architectural Design and Control Algorithms

This paper presents a transition-flight mathematical model of a civil tilt-rotor VTOL unmanned aerial vehicle (UAV) TURAC. Forces and moments acting on the UAV body are calculated using Newton's second law. Aerodynamic effects of free airstream and propeller airstream are defined separately. CFD analyses are performed to specify aerodynamic coefficients for transitional flight regime. The trim point is mathematically defined with respect to angle of attack, tilt angle, airspeed, thrust of tilt-rotor and coaxial fan are defined during transitional flight. A transitional flight scenario is developed with force and moment equations.

Dynamic modeling of a fixed-wing VTOL UAV

Over the last decade, the share of civilian Unmanned Aerial Vehicles (UAVs) in the general UAV market has steadily increased. These systems are being used more and more for applications ranging from crop monitoring to the tracking air emissions in high-pollution areas. Most civilian applications require UAVs to be low cost, portable, and easily packaged while also having Vertical Take-off and Landing (VTOL) capability. In light of this, the TURAC was designed, a VTOL Tilt Rotor UAV with these capabilities. Mathematical and CFD analyses were performed iteratively in order to optimize the design, but testing in actual conditions were needed. However, as with such an iterative design process, the manufacturing process costs, including different molds for each design, can be exorbitant. In addition, once an imperfection in the design is encountered, making design modifications on the full scale UAV prototype is difficult and expensive. Therefore, a cheap, rapid, and easily reproducible prototyping methodology is essential. In this study, the end result of an iterative design process of TURAC is presented. In addition, a low-cost prototyping methodology is developed and its application is demonstrated in detail. The ground and flight tests are applied on a fully functional prototype and the results are given.

Rapid Prototyping of a Fixed-Wing VTOL UAV for Design Testing

Over the last decade, the market share of civilian UAVs within the general UAV market has consistently increased. As such, these systems are increasingly being used for applications ranging from the monitoring of crops to the tracking of air emissions around high-pollution areas. Most of the civilian applications of UAVs require these vehicles to be of low-cost and for the portability and packaging to be easy while also having vertical take-off and landing capability. TURAC - a VTOL Tilt Rotor UAV with these capabilities - is designed. Although mathematical and CFD analyses were performed iteratively in order to optimize the design, testing in real life conditions were needed to see the real performance of the TURAC UAV. However, as with such an iterative design process, the manufacturing process costs, including different molds for each design, can be exorbitant. In addition, once an imperfection in the design is encountered, making radical design modifications on the UAV in real life is difficult and expensive. Therefore, a cheap, rapid, and easily reproducible prototyping methodology is essential. In this study, the end result of an iterative design process of TURAC is presented. In addition, a low-cost prototyping methodology is developed and its application is demonstrated in detail by explaining all of its phases. The ground and flight tests are applied on a fully functional prototype and the results are given.

Adil Yukselen

Papers

Dynamic modeling of a fixed-wing VTOL UAV

Rapid Prototyping of a Fixed-Wing VTOL UAV for Design Testing

A low cost prototyping approach for design analysis and flight testing of the TURAC VTOL UAV