Rotary-wing Unmanned Aerial Vehicle Research Articles

Flight Control of a Rotary wing UAV including Flapping Dynamics

AbstractThis paper presents the development and experimental implementation of a novel two-time scale controller for the hover control of a Rotary wing Unmanned Aerial Vehicle (RUAV). Flapping and servo dynamics, important from a practical point of view, are included in the RUAV model. The two-time scale controller takes advantage of the ‘decoupling’ of the translational and rotation dynamics of the rigid body, resulting in a two-level hierarchical control scheme. The inner loop (attitude control) tracks the attitude commands generated by the outer loop controller and sets the main rotor thrust vector, while the outer loop (position control) tracks the reference position. Hover flight experimental results are presented in this paper using the proposed two-time scale controller.

A Nonlinear Position Controller for Maritime Operations of Rotary-wing UAVs

AbstractThis paper presents a disturbance attenuation controller for horizontal position stabilization for hover and automatic landings of a Rotary-wing Unmanned Aerial Vehicle (RUAV) operating in rough seas. Based on a helicopter model representing aerodynamics during the landing phase, a nonlinear state feedback H∞ controller is designed to achieve rapid horizontal position tracking in a gusty environment. The resultant control variables are further treated in consideration of practical constraints (flapping dynamics, servo dynamics and time lag effect) for implementation purpose. The high-fidelity closed-loop simulation using parameters of the Vario helicopter verifies performance of the proposed position controller. It not only increases the disturbance attenuation capability of the RUAV, but also enables rapid position response when gusts occur. Comparative studies show that the H∞ controller exhibits great performance improvement and can be applied to ship/RUAV landing systems.

Minimum-time approach to obstacle avoidance constrained by envelope protection for autonomous UAVs

An integrated approach is needed for combining path planning for obstacle avoidance with envelop protection to ensure that a UAV is operated within its safe operational limits while maneuvering in obstacle fields. This paper presents a minimum-time approach to this problem by treating obstacle avoidance and envelope protection as inequality constraints in a state space formulation. The approach is used to study the guidance of a rotary wing UAV for aggressive maneuvering in avoiding an obstacle while staying within its operational envelope. The Nonlinear Trajectory Generator (NTG) is used as a real-time optimization solver, and load factor and rotor flapping angle are considered as limit parameters. A nonlinear simulation model of a rotary wing test bed within the Georgia Tech Unmanned Aerial Vehicle Simulation Tool (GUST) is used to evaluate the proposed approach.

Dynamic Compensation for Control of a Rotary wing UAV Using Positive Position Feedback

This paper presents a novel compensation method for the coupled fuselage-rotor mode of a Rotary wing Unmanned Aerial Vehicle (RUAV). The presence of stabilizer bar limits the performance of attitude control of an RUAV. In this paper, a Positive Position Feedback (PPF) is introduced to increase the stability margins and allow higher control bandwidth. The identified model is used to design a PPF controller to mitigate the presence of stabilizer bar. Parameters for the linear RUAV model are obtained by performing linear system identification about a few selected points. This identification process gives complete RUAV dynamics and is suitable for designing a Stability Augmentation System (SAS) of an RUAV. The identified parameters of an RUAV model are verified using experimental flight data and can be used to obtain the nonlinear model of an RUAV. The performance of the proposed algorithm is tested using a high-fidelity RUAV simulation model, which is validated through experimental flight data. The closed-loop response of the rotorcraft indicates that the desired attitude performance is achieved while ensuring that the coupled fuselage-rotor mode is effectively compensated without penalizing the phase response.

A computationally efficient approach for NN based system identification of a rotary wing UAV

Neural Network (NN) models based on autoregressive structures have long been used for nonlinear system identification problems. Their application for on-line implementations, however require them to be trained within a prescribed time span, which is often related to the sampling time of the system. In this paper, we introduce a NN model that is embedded with a dimensionality reduction mechanism in order to reduce the size of the network. The dimensionality reduction is based on Principal Component Analysis (PCA) and the resulting smaller NN trains faster. The longitudinal and lateral dynamics of a rotary wing Unmanned Aerial Vehicle (UAV) is modelled using flight test data. The results of system identification, error statistics and training times are provided to highlight the benefits of the proposed approach for NN based system identification models.

Conceptual Design of a Multi-Rotor Unmanned Aerial Vehicle based on an Axiomatic Design

This paper presents the conceptual design of a multi-rotor unmanned aerial vehicle (UAV) based on an axiomatic design. In most aerial vehicle design approaches, design configurations are affected by past and current design tendencies as well as an engineer's preferences. In order to design a systematic design framework and provide fruitful design configurations for a new type of rotorcraft, the axiomatic design theory is applied to the conceptual design process. Axiomatic design is a design methodology of a system that uses two design axioms by applying matrix methods to systematically analyze the transformation of customer needs into functional requirements (FRs), design parameters (DPs), and process variables. This paper deals with two conceptual rotary wing UAV designs, and the evaluations of tri-rotor and quad-rotor UAVs with proposed axiomatic approach. In this design methodology, design configurations are mainly affected by the selection of FRs, constraints, and DPs.

1A2-C17 後置静翼によるUAV姿勢制御機構の開発

In this paper, we propose a rotary-wing UAV(Unmanned Aerial Vehicle) that is more compact and has better flight stability as compared with the conventional ones. It is well-known that Rotary-wing airplanes require the mechanism to compensate a counter-torque. Therefore, in a series of studies, we have been developing a new compensating mechanism for the counter-torque. The mechanism has stators underneath the main-rotor, and controls attitude by lift of the stators. In this study, we have conducted a basic performance test of stators under the condition that the variable pitch main-rotor is utilized.

Rotary-Wing UAV Mission Planning Aided by Supervisory Control

In this paper, a method based on the supervisory control theory for hybrid systems is proposed to the mission planning of rotary-wing unmanned aerial vehicles (UAV). First, the mission is modeled by a hybrid automaton; then, by means of reachability techniques, a condition/event automaton, that represents the discrete-trace behavior of the hybrid automaton, is computed; and then the supervisory control theory is applied to obtain a discrete-trace behavior that avoids, under maximal permissiveness, the undesirable flight conditions, namely, the lack of fuel during the flight, the violation of time on target restrictions and the violation of trajectory margins. Computational tools were developed and a case-study is presented.

Aerodynamic parameter estimation from flight data applying extended and unscented Kalman filter

Aerodynamic parameter estimation is an integral part of aerospace system design and life cycle process. Recent advances in computational power have allowed the use of online parameter estimation techniques in varied applications such as reconfigurable or adaptive control, system health monitoring, and fault tolerant control. The combined problem of state and parameter identification leads to a nonlinear filtering problem; furthermore, many aerospace systems are characterized by nonlinear models as well as noisy and biased sensor measurements. Extended Kalman filter (EKF) is a commonly used algorithm for recursive parameter identification due to its excellent filtering properties and is based on a first order approximation of the system dynamics. Recently, the unscented Kalman filter (UKF) has been proposed as a theoretically better alternative to the EKF in the field of nonlinear filtering and has received great attention in navigation, parameter estimation, and dual estimation problems. However, the use of UKF as a recursive parameter estimation tool for aerodynamic modeling is relatively unexplored. In this paper we compare the performance of three recursive parameter estimation algorithms for aerodynamic parameter estimation of two aircraft from real flight data. We consider the EKF, the simplified version of the UKF and the augmented version of the UKF. The aircraft under consideration are a fixed wing aircraft (HFB-320) and a rotary wing UAV (ARTIS). The results indicate that although the UKF shows a slight improvement in some cases, the performance of the three algorithms remains comparable.

An Efficient Path Planning and Control Algorithm for RUAV’s in Unknown and Cluttered Environments

This paper presents an efficient planning and execution algorithm for the navigation of an autonomous rotary wing UAV (RUAV) manoeuvering in an unknown and cluttered environment. A Rapidly-exploring Random Tree (RRT) variant is used for the generation of a collision free path and linear Model Predictive Control(MPC) is applied to follow this path. The guidance errors are mapped to the states of the linear MPC structure by using the nonlinear kinematic equations. The proposed path planning algorithm considers the run time of the planning stage explicitly and generates a continuous curvature path whenever replanning occurs. Simulation results show that the RUAV with the proposed methodology successfully achieves autonomous navigation regardless of its lack of prior information about the environment.

Flight control of a rotary wing UAV using backstepping

This paper presents a novel application of backstepping controller for autonomous landing of a rotary wing UAV (RUAV). This application, which holds good for the full flight envelope control, is an extension of a backstepping algorithm for general rigid body velocity control. The nonlinear RUAV model used in this paper includes the flapping and servo dynamics. The backstepping-based controller takes advantage of the ‘decoupling’ of the translation and rotation dynamics of the rigid body, resulting in a two-step procedure to obtain the RUAV control inputs. The first step is to compute desired thrusts and flapping angles to achieve the commanded position and the second step is to compute control inputs, which achieve the desired thrusts and flapping angles. This paper presents a detailed analysis of the inclusion of a flapping angle correction term in control. The performance of the proposed algorithm is tested using a high-fidelity RUAV simulation model. The RUAV simulation model is based on miniature rotorcraft parameters. The closed-loop response of the rotorcraft indicates that the desired position is achieved after a short transient. The Eagle RUAV control inputs, obtained using high-fidelity simulation results, clearly demonstrate that this algorithm can be implemented on practical RUAVs. Copyright © 2009 John Wiley & Sons, Ltd.

Guidance Law for Vision-Based Automatic Landing of UAV

In this paper, a guidance law for vision-based automatic landing of unmanned aerial vehicles (UAVs) is proposed. Automatic landing is a challenging but crucial capability for UAVs to achieve a fully autonomous flight. In an autonomous landing maneuver of UAVs, the decision of where to landing and the generation of guidance command to achieve a successful landing are very significant problem. This paper is focused on the design of guidance law applicable to automatic landing problem of fixed-wing UAV and rotary-wing UAV, simultaneously. The proposed guidance law generates acceleration command as a control input which derived from a specified time-to-go (<TEX>$t_go$</TEX>) polynomial function. The coefficient of <TEX>$t_go$</TEX>-polynomial function are determined to satisfy some terminal constraints. Nonlinear simulation results using a fixed-wing and rotary-wing UAV models are presented.

일본의 민간 회전익 무인항공기 (UAV) 현황

일본의 민간 회전익 무인항공기 (UAV) 현황

Rotary wing UAV potential applications: an analytical study through a matrix method

Industrial designers often need decision‐making methods to develop innovative solutions combining specified customer's requirements with project technical constraints. This paper describes a matrix approach as a technique to support system designer since the early stages of development, when many and important decisions must be taken. In this work, the matrix method has been used to analyze the civil unmanned aerial vehicle potential market and particularly for selecting the most promising applications of a multi‐role rotary wing unmanned aerial vehicle. According to the matrix results, two rotary wing multi‐role missions have been chosen as most promising customer attractive applications. This matrix method can also be improved for subsequent decision‐making in preliminary‐configuration analysis since it can be easily tailored to different specific engineering applications.

회전익 무인 항공기의 임무 요구 및 개발동향

회전익 무인 항공기의 임무 요구 및 개발동향