Tilt-rotor Unmanned Aerial Vehicle Research Articles

Design, Modeling, and Control of a Composite Tilt-Rotor Unmanned Aerial Vehicle

Tilt-rotor unmanned aerial vehicles combine the advantages of multirotor and fixed-wing aircraft, offering features like rapid takeoff and landing, extended endurance, and wide flight conditions. This article provides a summary of the design, modeling, and control of a composite tilt-rotor. During modeling process, aerodynamic modeling was performed on the tilting and non-tilting parts based on the subcomponent modeling method, and CFD simulation analysis was conducted on the entire unmanned aerial vehicle to obtain its accurate aerodynamic characteristics. In the process of modeling the motor propeller, the reduction of motor thrust and torque due to forward flow and tilt angle velocity is thoroughly examined, which is usually ignored in most tilt UAV propeller models. In the controller design, this paper proposes a fusion ADRC control strategy suitable for vertical takeoff and landing of this type of tiltrotor. The control system framework is built using Simulink, and the control algorithm’s efficiency has been verified through simulation testing. Through the proposed control scheme, it is possible for the composite tiltrotor unmanned aerial vehicle to smoothly transition between multirotor and fixed-wing flight modes.

Design of flight control system of Quad Tilt Rotor UAV based on PID algorithm

This research focuses on the quadrotor tiltrotor unmanned aerial vehicle and considers various usage scenarios such as battlefield and transportation environments, as well as flight stability issues in complex meteorological environments. A PID control algorithm for rotor angle control of quadrotor tiltrotor unmanned aerial vehicles is designed, which is suitable for different usage scenarios and meteorological conditions.

Analysis of the Pneumatics principles of several aircrafts

In recent years, the advancement of science and technology, particularly the development of flight control technology, has driven the progress of aircraft technology, which facilitates the rapid development of many kinds of aircraft. Pneumatics, the mechanics of gas flow, is used to study aerodynamics. In the design and manufacturing of aircraft, gas flow has a significant impact on the movement, control, attitude, stability, and other aspects of the aircraft. This paper describes the basic Pneumatics principles in aircraft design: aerodynamics is the discipline that studies the interaction between airflow and aircraft, it is the core foundation of aircraft external shape design, a pivotal discipline in overall design, and a prerequisite for conducting design analyses in fields, it plays a crucial role in aircraft design and force analysis for the aircraft, and this paper also introduces the aerodynamic layout design and aerodynamic characteristics of tilt-rotor Unmanned Aerial Vehicle (UAV), multi-rotor aircraft and bionic flapping wing aircraft, so as to offer some references for future study of air vehicles.

Design and analysis of an electric tiltrotor unmanned aerial vehicle

The concept of tiltrotor aircraft has been around for over seventy years, but it was not until the last decade that the advancement in Unmanned Aerial Vehicle (UAV) technology has made them a viable option. Although the design requirements of such UAV are complex and require careful consideration, the potential benefits are significant. Motivated by their potential capabilities, this paper aims to present a complete procedure for designing an electric tiltrotor UAV that incorporates the attributes of both fixed and rotary wing aircraft, including all necessary mathematical formulations. The paper explores the diverse aspects of the design and analysis of tiltrotor UAVs, from conceptual, preliminary, and detail design to aerodynamics, performance, and stability analysis. The detailed weight analysis is performed using six different methods from different references to assess their applicability for use with electric tiltrotor UAV. After designing and selecting the UAV components, an iteration process is performed to check and resize the estimated design parameters.

Simulation of tilt-rotor UAV flight dynamics in horizontal flight

Tilt-rotor unmanned aerial vehicles (UAV) have gained significant importance in the aeronautical industry due to their ability to transition between vertical and horizontal flight. One of the important steps in the development of such UAVs is to assess their performance and stability characteristics. Simulation of flight dynamics is an essential tool that enables the designers to test and optimize the flight characteristics of these UAVs. This paper presents a complete procedure for developing a 6-degree-of-freedom flight dynamics model of a tilt-rotor UAV in fixed-wing mode using a physics-based modeling approach. All necessary sub-models are developed and integrated into the Simulink simulation environment to allow for predicting the UAV’s dynamic response. The developed model is verified for correct operation by simulating horizontal steady-level flight and exciting its natural longitudinal modes.

Development of Multimode Flight Transition Strategy for Tilt-Rotor VTOL UAVs

The purpose of this paper is to establish a transition strategy for tilt-rotor vertical takeoff and landing (VTOL) unmanned aerial vehicles (UAVs) based on an optimal design method. Firstly, The flyable transition corridor was calculated based on both the UAV’s dynamic equations and its aerodynamic and dynamic characteristics. The dynamic equations of the UAV were organized into state equation forms. The initial and final value constraints of the control and state variables in the transition process were recorded, as were the constraints of the transition process. The transition strategy design problem was transformed into an optimal control problem with constraints, while the Gauss pseudospectral method (GPM) was employed to transform and solve the problem. In addition, performance indicators were designed based on the transition quality requirements for transition time, attitude stability, and control continuity. Sensitivity was analyzed according to different index terms with different dimensions and effects. Finally, the rationality of the transition strategy designed in this paper was verified according to different simulation scenarios.

Modeling and Dynamic Stability Analysis of Distributed Electric Propulsion Tilt-Rotor UAV

Distributed electric propulsion tilt-rotor unmanned aerial vehicles (TRUAVs) with a lift-increasing flap in the propulsion wake have better aerodynamic efficiency than traditional tilt-rotor unmanned aerial vehicles and better takeoff/landing capacity than fixed-wing aircraft. However, for this configuration, establishing the propulsion–aerodynamic coupling model between the flap and the duct is difficult. This paper presents a flight dynamics model with propulsion–aerodynamic coupling components and analyzes dynamic characteristics during the transition period for TRUAVs with a distributed-propulsion/flap configuration. The development of the flight dynamics model considers the descriptions of the duct model, the lift-increasing flap model, and the propeller model. The model of the lift-increasing flap in both the duct exhaust jet and the freestream is the key component of the vehicle dynamics equations and is validated with experimental data and computational fluid dynamics results. Based on the dynamics model, the transition corridor of the tilt-rotor aircraft with multiple asynchronous tilting components and a geometrical constraint is calculated and analyzed. Additionally, the longitudinal dynamics stability of the aircraft in different flight speeds and configurations is assessed based on the numerical differentiation method. The results showed that the vehicle flight speed has more influence on longitudinal short-period stability than the angle of attack (AOA) of the flap. Also, the longitudinal long-period stability is affected by both the vehicle flight speed and the AOA of the flap. Finally, a mathematical derivation is developed to analyze the aircraft’s unstable state. The presented analysis results show that the stability of the long period is affected by the velocity derivative of the fuselage’s lift.

Transition Nonlinear Blended Aerodynamic Modeling and Anti-Harmonic Disturbance Robust Control of Fixed-Wing Tiltrotor UAV

This study proposed a novel nonlinear blended aerodynamic model for the tiltrotor unmanned aerial vehicle (UAV) during the transition phase to handle the high angle-of-attack (AoA) flight, which aggregated the flat-plate mode and the linear mode of the aerodynamic coefficients. Additionally, a harmonic disturbance observer (HDO) and super-twisting sliding mode controller (STSMC) addressed the fast-changing external disturbances and attenuated the chattering problem in the original SMC. The comparative trajectory tracking results indicated that the blended aerodynamic model accurately tracks the reference signals with no tracking errors, which demonstrated a superior performance as compared to the traditional aerodynamic model, with a reduction of 2.2%, 50%, 73.6%, and 11.2% in the time required for tracking the pitch angle, pitch rate, and velocities u and w, respectively. Conversely, the traditional one exhibited significant tracking errors, ranging from 0.016° in the pitch angle channel to 1.25°/s in the pitch rate channel, and 0.6 m/s for velocity u and 0.01 m/s for velocity w. Moreover, the comparative control input results illustrated that the least control effort was required for the proposed HDO-STSMC control scheme with a blending function, while the original ESO-SMC experienced more oscillations and sharp amplitude changes, taking twice the time to converge, with considerable tracking errors such as 1.067° in the pitch angle channel, 0.788°/s in the pitch rate channel, 1.554 m/s for velocity u, and 0.746 m/s for velocity w, which verified the feasibility and superiority of the proposed HDO-STSMC with the blending function. Two performance indices revealed the robust stability and rapid convergence of the proposed transition blended aerodynamic model with the HDO-STSMC control scheme.

A Preliminary Study on the Development of a New UAV Concept and the Associated Flight Method

This article presents a preliminary study on the development of a new concept for an unmanned aerial vehicle (UAV) design that incorporates the use of four wings and attached systems to improve overall performance, it being classified as a hybrid quadcopter (a quad tilt wing, tiltrotor UAV). By simulation, it was determined that the developed concept has significant advantages compared with a conventional quadcopter. By implementing this concept, an increase in the maximum speed by 59.21% can be obtained; it reduces time to complete a 10 km route by 36.4%, decreases the energy consumption by 37%, and increases the maximum travel distance by 56.9% at 30% remaining battery capacity. Additionally, the concept improves maneuverability by allowing turning movements to be performed by changing the angle of incidence of the rear wings, resulting in less energy consumption compared to traditional turning methods applied in the case of a conventional quadcopter.

A review analysis of tilt rotor unmanned aerial vehicles

TRUAVs (Tilt Rotor Unmanned Aerial Vehicles) are a new technology that is becoming more and more popular in today's modern world for a range of uses, including agricultural, civil engineering, target tracking, search and salvage operations, and surveillance. Such aerial vehicles were created as a solution to a number of issues, such as the lack of runways in remote and heavily forested areas. The TRUAV is a hybrid aircraft that presents the advantages of both conventional aero plane and helicopter technology in a single aircraft. This review article is largely concerned with the design and analysis of Tilt Rotor Unmanned Aerial Vehicles (TRUAV). The flight control legislation we developed has a straightforward design and excellent technical dependability.

ОПРЕДЕЛЕНИЕ ЦЕНТРА ТЯЖЕСТИ БЕСПИЛОТНОГО ЛЕТАТЕЛЬНОГО АППАРАТА КОНВЕРТОПЛАНОВОГО ТИПА

The article analyzes research work in the direction of the correct location of the load center,centering and gravity of the aircraft at the design and manufacturing stage in order to improve theefficiency and safety of flights, as well as the characteristics of existing methods and means, and,using the example of a tiltrotor unmanned aerial vehicle, a methodology for using the known the"scale-graph" method, which is widely used in determining the center of gravity of an aircraft.When determining the mass of the tiltrotor-type unmanned aerial vehicle designed and developedby us and calculating the coordinates of the center of gravity, an analysis of the standard deviationand probable error was carried out. The characteristics and possibilities of practical applicationof mobile electronic scales as the main means of measuring the load of an unmanned aerialvehicle in stationary conditions, as well as direct weighing, which makes it possible to determinethe center of gravity, are considered. A method developed for determining the center of gravity ofan aircraft with increased accuracy is described, and a model for constructing the proposedsystem is presented. The results of theoretical and experimental studies carried out to determine the mass and center of gravity of an unmanned aerial vehicle are analyzed. To do this, inaccordance with the methodology, the plane of the laboratory table was brought to ahorizontal position with a level gauge and the measurement errors of digital measuringscales were checked according to the results of measuring the reference load. Themeasurements were repeated by changing the position of the scales clockwise. According tothe measurement results, since the center of gravity of the aircraft was taken differently onboth axes, and the intermediate point fell outside the central axis (to the right or left, front toback), repeated measurements were taken by shifting the load in the appropriate direction toensure centering during measurements. According to the final results, center of gravitydiagrams were constructed based on the calculated values of the coordinates of the points ofintersection of the diagonals and random slope values were determined. Based on thediagrams constructed using the program, the final graph was obtained with the root-meansquareerror of the deviation of the aircraft from the axis of symmetry, equal to σ=0.047 sm.

Study of Modeling and Optimal Take-Off Scheme for a Novel Tilt-Rotor UAV.

The optimal trajectory planning for a novel tilt-rotor unmanned aerial vehicle (UAV) in different take-off schemes was studied. A novel tilt-rotor UAV that possesses characteristics of both tilt-rotors and a blended wing body is introduced. The aerodynamic modeling of the rotor based on blade element momentum theory (BEMT) is established. An analytical method for determining the taking-off envelope of tilt angle versus airspeed is presented. A novel takeoff-tilting scheme, namely tilting take-off (TTO), is developed, and its optimal trajectory is designed based on the direct collocation method. Parameters such as the rotor thrust, tilt angle of rotor and angle of attack are chosen as control variables, and the forward velocity, vertical velocity and altitude are selected as state variables. The time and the energy consumption are considered in the performance optimization indexes. The optimal trajectories of the TTO scheme and other conventional schemes including vertical take-off (VTO) and short take-off (STO) are compared and analyzed. Simulation results indicate that the TTO scheme consumes 47 percent less time and 75 percent less energy than the VTO scheme. Moreover, with minor differences in time and energy consumption compared to the STO scheme, but without the need for sliding distance, TTO is the optimal take-off scheme to satisfy the flight constraints of a novel tilt-rotor UAV.

A Fuzzy Backstepping Attitude Control Based on an Extended State Observer for a Tilt-Rotor UAV

In order to overcome the influence of internal and external disturbances caused by rotor tilt motion and gust disturbance on the full flight mode control of a tilt-rotor unmanned aerial vehicle (UAV), a design method using fuzzy backstepping control based on an extended-state observer (FBS-ESO) is proposed. In this paper, fuzzy control is used to tune the parameters of the backstepping control law online, and the extended-state observer estimates the total disturbance of the controlled system to improve the controller’s robustness and anti-disturbance capability. This paper designs the attitude control system of a tilt-rotor UAV based on an FBS-ESO controller. The control performance of the FBS-ESO controller is tested in a hardware-in-loop simulation of the attitude control system. The simulation results show that changing the rotor tilt angle will destroy the stability of the traditional backstepping controller and active disturbance rejection controller (ADRC). In contrast, the FBS-ESO controller maintains good control performance. In addition, the performance of the FBS-ESO controller is not be significantly affected by adding external gust disturbance or changing the UAV parameters in the simulation. These disturbances significantly impact the traditional backstepping controller and ADRC. Therefore, the FBS-ESO controller has better anti-disturbance capabilities and robustness, as well as higher attitude control accuracy.

Dynamic Modeling and Control for Tilt-Rotor UAV Based on 3D Flow Field Transient CFD

The tilt-rotor unmanned aerial vehicle (TRUAV) is characterized by both multi-rotor vertical takeoff or landing and fixed-wing long-duration flight. Not only the structure of TRUAV is complex, but also the aerodynamic coupling is severe. Especially when the TRUAV is in the transition mode, the rotor flow field and wake are complicated. The abnormal variation of the aerodynamic force of the rotor blades will directly affect the balance and manipulation of the aircraft. The downwash flow generated by the rotor spiral propeller tip vortex interference will impact the wing from every direction, forming a blocked three-dimensional effect flow field on the wing surface, which seriously affects the stability of the UAV. In this paper, the transient CFD (Computational Fluid Dynamics) numerical simulation was applied to examine the flow fields of the fuselage and rotor under the transition modal of TRUAV as well as the aerodynamic disturbance. In addition, the dynamics model of the TRUAV was established based on the change of the tilt angle state, and considering the effect of rotor slip flow, we analyzed the three-dimensional flow field distribution of TRUAV in the transition mode under the aerodynamic disturbance of the fuselage and rotor, and we identified each aerodynamic parameter required for modeling. A cascade PID control strategy is designed for the TRUAV, and the results verify that the proposed TRUAV model can remain stable even when the maximum roll angle is 20 degrees. At last, the simulation results provide data support for the optimization of the TRUAV aerodynamic profile and the design of subsequent flight control methods.

Adaptive Attitude Control for a Coaxial Tilt-Rotor UAV via Immersion and Invariance Methodology

Dear Editor, This letter is concerned with the attitude control for a novel tilt-rotor unmanned aerial vehicle with two pairs of tiltable coaxial rotors and one rear rotor. An immersion and invariance-based adaptive attitude controller for the tilt-rotor unmanned aerial vehicle is proposed. In the proposed control strategy, an adaptive update law is specially designed to compensate for the uncertainties of damping coefficients. The stability of the resulting closed-loop coaxial tilt-rotor unmanned aerial vehicle (CTRUAV) system is proved by the Lyapunov methodology and LaSalle's invariance theory. Finally, to validate the effectiveness of the designed control strategy, simulations and experiments are performed.

Real-time parameter identification method for a novel blended-wing-body tiltrotor UAV

An accurate aircraft dynamic model is essential for the flight control system design and flight characteristic analysis of tiltrotor unmanned aerial vehicle (UAV). The unique aerodynamic interaction between the rotor and wing and the installation misalignment angles of rotor could obviously degrade the control performance of flight. However, the traditional test-bed-based identification method cannot fully simulate the real flying conditions. Thus, a real-time method based on the Error-State Kalman Filter (ESKF) is proposed to estimate the model parameters of the tiltrotor UAV. Based on the navigation information from the onboard integrated navigation system, the model parameters are augmented into the aircraft dynamic model to be estimated. Then, the observability analysis is carried out to demonstrate the convergence of the proposed method and provide the proper measurements from which the model parameters possess the best observable degree. Finally, both simulations and real flight experiments are performed to validate the effectiveness of the proposed method.

Closed Loop Performance Analysis of Classical PID and Robust H-infinity Controller for VTOL Unmanned Quad Tiltrotor Aerial Vehicle

Unmanned Aerial Vehicles (UAVs) guidance, control and navigation have directed the attention of many researchers in both aerospace engineering as well as control theory. Due to the unique rotor structure of Tiltrotor hybrid UAVs, they exhibit special application value. Quad Tiltrotor UAVs set up a distinctive platform that satisfies the needs of the varying mission requirements by combining the conventional features of high-speed cruise capabilities of an aircraft and hovering capabilities of a helicopter and by tilting its four rotors. The aim of this research article is to control the attitude and altitude of the UAV in the presence of uncertainty using two different control techniques. This paper addresses the comparative analysis of the robust H-infinity controller with classical PID control designs for the transition manoeuvre of a hybrid UAV: the VTOL Tiltrotor UAV. The proposed controllers achieve hover to cruise mode transition and vice-versa. The main idea behind the design of controller is to model and analyze the UAV’s position and attitude dynamics. The desired flight trajectory and the transition manoeuvre is achieved by controlling the tilt angle in 15° intervals from 90° to 0° and vice-versa. Performance index subjected to IAE is estimated and compared for both the controllers in the presence of noise, disturbances and uncertainties. The results of simulation illustrate that the robust H-infinity controller achieves better transition, good adaptability, robust performance and robust stability for the whole flight envelope when compared with the PID controller.

Design, Analysis, and Testing of a Hybrid VTOL Tilt-Rotor UAV for Increased Endurance

Unmanned Aerial Vehicles (UAVs) have slowly but steadily emerged as a research and commercial hotspot because of their widespread applications. Due to their agility, compact size, and ability to integrate multiple sensors, they are mostly sought for applications that require supplementing human effort in risky and monotonous missions. Despite all of these advantages, rotorcrafts, in general, are limited by their endurance and power-intensive flight requirements, which consequently affect the time of flight and operational range. On the other hand, fixed-wing aircrafts have an extended range, as the entire thrust force is along the direction of motion and are inherently more stable but are limited by their takeoff and landing strip requirements. One of the potential solutions to increase the endurance of VTOL rotorcrafts (Vertical Take-Off and Landing Vehicles) was to exploit the thrust vectoring ability of the individual actuators in multi-rotors, which would enable take-off and hovering as a VTOL vehicle and flight as a fixed-wing aircraft. The primary aim of this paper is to lay out the overall design process of a Hybrid VTOL tilt-rotor UAV from the initial conceptual sketch to the final fabricated prototype. The novelty of the design lies in achieving thrust vectoring capabilities in a fixed-wing platform with minimum actuation and no additional control complexity. This paper presents novel bi-copter that has been designed to perform as a hybrid configuration in both VTOL and fixed wing conditions with minimum actuators in comparison to existing designs. The unified dynamic modelling along with the approximation of multiple aerodynamic coefficients by numerical simulations is also presented. The overall conceptual design, dynamic modeling, computational simulation, and experimental analysis of the novel hybrid fixed-wing bi-copter with thrust vectoring capabilities aiming to substantially increase the flight range and endurance compared to the conventional aircraft rotorcraft configurations are presented.

Conversion control of a tilt tri-rotor unmanned aerial vehicle with modeling uncertainty

The tilt-rotor unmanned aerial vehicle (TRUAV) has vertical take-off and landing and high-speed flight capabilities through conversion and reconversion modes, thereby presenting wide application prospects. This article presents a compact tilt tri-rotor UAV. For flying in the conversion mode, the TRUAV needs to realize the transition of two control logic and two kinds of actuators in both of the rotor and fixed-wing modes, achieving the control of the multi-input multioutput, input nonaffine, and nonlinear multichannel cross-coupling UAV system. Furthermore, the lateral dynamics of a tilt tri-rotor UAV is more unstable for unpaired rotors. These system characteristics present a great challenge to conversion control. To solve these problems, the nonlinear dynamic model of the vehicle in the conversion mode is provided. Furthermore, a cascade control system consisting of position control, velocity control, angle control, angular velocity control, and control mixer is proposed. The simulation result of the control system shows steady flight and a fast transition in the conversion mode with modeling uncertainty in case of no wind.

Flight Test Evaluation for Tilt Rotor Unmanned Aerial Vehicle Development

Tiltrotor Unmanned Aerial Vehicle (UAV) is type of UAV that combine fixed wing (FW) and multirotor (VTOL) configuration in order to be able to perform instant transition from one configuration to another. Tiltrotor UAV has advantage to perform takeoff and landing from limited space such as plantation farm, forest, and residential area. Tiltrotor also can carry various mission since it has 2 configuration such as cargo drone, safer payload dropping, and mapping. In this research tiltrotor UAV designed with ruddervator (V-Tail) configuration with 3 motors in total, 2 motors placed on main wing with tilting capability and 1 motor placed at the end of fuselage as pitch controller in VTOL mode. Test flight will be conducted and evaluated to test UAV capability in hovering and transition from one mode to another