I WIG’s: MEZZI INNOVATIVI PER IL TRASPORTO CIVILE Un’ipotesi di impiego per i collegamenti a medio raggio nel Mediterraneo

An Extended Kalman Filter-Based Technique for On-Line Identification of Unmanned Aerial System Parameters

ABSTRACT: The present article deals with the identification, at the same time, of aircraft stability and control parameters taking into account dynamic damping derivatives. Such derivatives, due to the rate of change of the angle of attack, are usually neglected. So the damping characteristics of aircraft dynamics are attributed only on pitch rate derivatives. To cope with the dynamic effects of these derivatives, authors developed devoted procedures to estimate them. In the present paper, a complete model of aerodynamic coefficients has been tuned-up to identify simultaneously the whole set of derivatives. Besides, in spite of the employed reduced order model and/or decoupled dynamics, a s…

State Estimation of a Nonlinear Unmanned Aerial Vehicle Model using an Extended Kalman Filter

An Extended Kalman Filter is designed in order to estimate both state variables and wind velocity vector at the same time for a non conventional unmanned aircraft. The proposed observer uses few measurements, obtained by means of either conventional simple air data sensors or a low cost GPS. To cope with the low rate of the GPS with respect to the other sensors, the EKF algorithm has been modified to allow for a dual rate measurement model. State propagation is obtained by means of an accurate six degrees of freedom nonlinear model of the aircraft dynamics. To obtain joint estimation of state and disturbance, wind velocity components are included in the set of the state variables. Both stoc…

AUTOMATIC TAKE-OFF OR LANDING PATH FOLLOWING IN TURBULENT AIR FOR UAS - AN EKF BASED PROCEDURE

By using the Extended Kalman Filter (EKF) an accurate take-off or landing flight path following in turbulent air is performed. The tuned up procedure employs simultaneously two different EKF: the first one estimates gust disturbances, the second one affords to determine the necessary controls displacements for rejecting those ones. In particular, the first filter, by using instrumental measurements gathered in turbulent air, estimates wind components. The second one obtains command laws able to follow the desired flight path. To perform this task aerodynamic coefficients have been modified by adding entirely new derivatives or synthetic increments to basic ones whose might the kind of chang…

Dynamic Stability of Wing in Ground effect Vehicles: A General Model

Automatic Landing System for Civil Unmanned Aerial System

In spite of a number of potentially valuable civil UAS applications The International Regulations prohibit UAS from operating in the National Air Space. Maybe the primary reasons are safety concerns. In fact their ability to respond to emergent situations involving the loss of contact between the aircraft and the ground station poses a serious problem. Therefore, to an efficient safe insertion of UAS in the Civil Air Transport System one important element is their ability to perform automatic landing afterwards the failure. Moreover, the mathematical model of ground effect is usually neither included in the model of the aircraft during takeoff and landing nor in the design requirements of t…

Wind Shear On-Line Identification for Unmanned Aerial Systems

An algorithm to perform the on line identification of the wind shear components suitable for the UAS characteristics has been implemented. The mathematical model of aircraft and wind shear in the augmented state space has been built without any restrictive assumption on the dynamic of wind shear. Due to the severe accelerations on the aircraft induced by the strong velocity variation typical of wind shear, the wind shear effects have been modeled as external forces and moments applied on the aircraft. The identification problem addressed in this work has been solved by using the Filter error method approach. An Extended Kalman Filter has been developed to propagate state. It has been tuned …

Flight Control Research Laboratory Unmanned Aerial System flying in turbulent air: an algorithm for parameter identification from flight data

This work addresses the identification of the dynamics of the research aircraft FCRL (Flight Control Research Laboratory) used for the Italian National Research Project PRIN2008 accounting for atmospheric turbulence. The subject vehicle is an unpressurized 2 seats, 427 kg maximum take of weight aircraft. It features a non retractable, tailwheel, landing gear and a powerplant made up of reciprocating engine capable of developing 60 HP, with a 60 inches diameter, two bladed, fixed pitch., tractor propeller. The aircraft stall speed is 41.6 kts, therefore it is capable of speeds up to about 115 kts (Sea level) and it will be cleared for altitudes up to 10.000 ft. The studied aircraft is equipp…

Mezzi innovativi di trasporto per i collegamenti a breve raggio

Optimal Flight Path Determination in Turbulent Air: A Modified EKF Approach

By using the Extended Kalman Filter an accurate path following in turbulent air is performed. The procedure employs simultaneously two different EKFs: the first one estimates disturbances, the second one affords to determine the necessary controls displacements for rejecting those ones. To tune the EKFs an optimization algorithm has been designed to automatically determine Process Noise Covariance and Measurement Noise Covariance matrices. The first filter, by using instrumental measurements gathered in turbulent air, estimates wind components. The second one obtains command laws able to follow the desired flight path. To perform this task aerodynamic coefficients have been modified. Such a…

Trajectory tracking for a Non-Conventional UAV

The aim of the present paper is the design of a flight control system for a Tandem – Canard UAV, useful in the whole flight envelope, both Out of Ground Effect (OGE) and In Ground Effect (IGE) conditions. Because of the particular arrangement of the studied aircraft, a general mathematical model has been built in order to obtain non-linear analytical equations for longitudinal aerodynamic coefficients both in OGE and in IGE flight. So the dynamic behaviour of the UAV may be studied during every flight phases i.e. in the whole range of altitude. To consider the strong variation of aerodynamic parameters due to the ground effect presence, a robust control technique (LQG/LTR) has been used to …

Wind component estimation for UAS flying in turbulent air

One of the most important problem of autonomous flight for UAS is the wind identification, especially for small scale vehicles. This research focusses on an identification methodology based on the Extended Kalman Filter (EKF). In particular authors focus their attention on.the filter tuning problem. The proposed procedure requires low computational power, so it is very useful for UAS. Besides it allows a robust wind component identification even when, as it is usually, the measurement data set is affected by noticeable noises. (C) 2019 Elsevier Masson SAS. All rights reserved.

CONTROLLO NON LINEARE DI TRAIETTORIE DI VELIVOLI AUTONOMI

A feasibility analysis of civil rotorcraft intercity passenger transport services

A Non Conventional UAV In Ground Effect: Synthesis of a Robust Flight Control System,

ABSTRACT This paper discusses the synthesis of an Extended Kalman Filter (EKF) to perform both wind velocities and state estimation for a non conventional UAV flying in ground effect. Since, in IGE flight, motions into the symmetry plane are of primary concern, the study focuses on the longitudinal aircraft dynamics. The proposed estimator requires measurement of few flight variables, easily obtainable by means of conventional sensors; besides, it does not use Inertial Measurement Unit (IMU). To simulate a low cost sensing equipment, the model outputs are corrupted by white noise of relatively high standard deviation. Furthermore, to cope with the low rate of the GPS with respect to the oth…

An Algorithm for Parameter Identification of UAS from Flight Data

The aim of the present work is to realize an identification algorithm especially devoted to UAS (unmanned aerial systems). Because UAS employ low cost sensor, very high measurement noise has to be taken into account. Therefore, due to both modelling errors and atmospheric turbulence, noticeable system noise has also to be considered. To cope with both the measurement and system noise, the identification problem addressed in this work is solved by using the FEM (filter error method) approach. A nonlinear mathematical model of the subject aircraft longitudinal dynamics has been tuned up through semi-empirical methods, numerical simulations and ground tests. To take into account model nonlinea…

Controllo Robusto delle Traiettorie in Effetto Suolo di un UAV Multisuperficie

Collision Avoidance Trajectory for an Ekranoplan.

The risk of collision is one of the crucial aspects for the applications of Ekranoplans in civil transportation. In fact, the extremely low flight altitude of these aircraft increases dramatically the chances of interference between their flight path and the multitude of obstacles populating the surrounding area. In this work we consider the optimal collision avoidance problem between a cruising Ekranoplan and a steady obstacle located on its flight path. First we solve the optimal control problem imposing that the collision avoidance maneuver lies on the longitudinal plane identified by the initial cruising conditions. In the second part of this work we state the three-dimensional version …

Preliminary design of an unmanned Wing In Ground effect craft.

This paper describes a systematic technique for preliminary conceptual design of Unmanned Wing in Ground Effect Craft (U-WIGs). Application of the methodology to a small U-WIG to be employed in tasks like coastal patrolling, oceanography, civil protection, control and monitoring, is presented. A mission profile and numerical mission specifications on minimum payload weight conveyable, cruising speed, minimum cruising altitude and autonomy suitable for the intended craft duties are imposed. On the basis of such specifications, take off weight is estimated via the fuel fraction method. Due to the lack of statistical information for small sized unmanned WIGs, data available for UAVs are used, …

Trajectory tracking for an Ultralight WIG

In this paper we present our research about a particular ultralight WIG. We have carried out the design of a Flight Control System that has to fix the control variables trend through a non-linear mathematical model, because of the particular geometric and aerodynamic configuration of this WIG. So, the non-linear mathematical model design has to reproduce exactly the aircraft behaviour either OGE or IGE. In particular, through classical semi-empirical relations, analytical equations have been obtained in order to evaluate incidence variations, downwash and upwash angles due to the ground. In the present paper only longitudinal dynamic is considered, because of its peculiarity in WIG's aircra…

AN EXTENDED KALMAN FILTER BASED TECHNIQUE FOR ON-LINE IDENTIFICATION OF UAS PARAMETERS.

The present article deals with the identification,at the same time, of aircraft stability and control parameters taking into account dynamic damping derivatives. Such derivatives,due to the rate of change of the angle of attack, are usually neglected. So the damping characteristics of aircraft dynamics are attributed only on pitch rate derivatives. To cope with the dynamic effects of these derivatives, authors developed devoted procedures to estimate them. In the present paper, a complete model of aerodynamic coefficients has been tuned-up to identify simultaneously the whole set of derivatives. Besides, in spite of the employed reduced order model and/or decoupled dynamics, a six degrees o…

Engineering requirements for avionics of unmanned aerial system

Within the framework of the European Project WInSiC4AP, the Unmanned Aerial Vehicle (UAV) use case plays an important role in defining some of the specific constraints that on-board electronics systems must obey. Then it’s relevant to have clear view of the UAVs classification and their main characteristics especially with the focus of an Electrical UAV. Main component of the power supply are batteries, whose requirements must fulfil the tight design constraint such as lightweight, safety, pressure and temperature tolerance, cost effectiveness and cycle life. A quick look to available chemistry technology as well as market overview has been described. Regarding the power sub-system, the key…

An EKF Based Method for Path Following in Turbulent Air

An innovative use of the Extended Kalman Filter (EKF) is proposed to perform both accurate path following and adequate disturbance rejection in turbulent air. The tuned up procedure employs simultaneously two different EKF: the first one estimates gust disturbances, the second one estimates modified aircraft parameters. The first filter, by using measurements gathered in turbulent air, estimates both aircraft states and wind components. The second one, by using the estimated disturbances, obtains command laws that are able to reject disturbances. The predictor of the second EKF uses the estimated wind components to solve motion equations in turbulent air. Besides a set of unknown stability …

Estimation of turbulence and state based on EKF for a tandem Canard UAV

This paper deals with the state and turbulence estimation of a model describing the longitudinal dynamics of an Unmanned Aerial Vehicle (UAV). Due to both the high nonlinearities of the model and the stochastic nature of disturbances, an Extended Kalman Filter (EKF) is proposed. To allow the estimator to be employed on low cost UAV systems, it is assumed that the aircraft is equipped with a low performance GPS, characterized by a relatively low refresh rate. The designed EKF is able to work efficiently in both turbulent and calm atmosphere. In order to obtain information about the performances of the proposed estimator for control purposes, a control system, consisting of the EKF, a PID-typ…

A NON CONVENTIONAL UAV IN GROUND EFFECT: ESTIMATION OF STATE AND TURBULENCE VIA EXTENDED KALMAN FILTER

ABSTRACT This paper discusses the synthesis of an Extended Kalman Filter (EKF) to perform both wind velocities and state estimation for a non conventional UAV flying in ground effect. Since, in IGE flight, motions into the symmetry plane are of primary concern, the study focuses on the longitudinal aircraft dynamics. The proposed estimator requires measurement of few flight variables, easily obtainable by means of conventional sensors; besides, it does not use Inertial Measurement Unit (IMU). To simulate a low cost sensing equipment, the model outputs are corrupted by white noise of relatively high standard deviation. Furthermore, to cope with the low rate of the GPS with respect to the oth…

Mathematical Model of Unmanned Aircraft In Ground Effect for Optimal Collision Avoidance

The fundamental aim of the present paper is to model the aerodynamic characteristics of an Unmanned Aerial Vehicle(UAV) flying in ground effect. The second aim is to determine the relationship between the optimal avoidance maneuver and the control to execute it. In fact, this relationship is basilar to the development of a guidance scheme capable of approximating the optimal trajectory in real time. In the first part of this work ,a non-linear model is built in order to model the aerodynamic characteristics of an UAV flying In Ground Effect. To use a single model in the whole range of flying altitude, aerodynamic coefficients are modeled by means of hyperbolic equations. In particular, thes…

Turbolence and State Estimation Via Extended Kalman Filter for a Non Conventional UAV

Automatic EKF tuning for UAS path following in turbulent air

By using two simultaneously working Extended Kalman Filters, a procedure is implemented in order to perform in a fully autonomous way the path following in turbulent air. To guarantee the robustness of the proposed algorithm, an automatic tuning procedure is proposed to determine optimal values of Process and Measurement Noise statistics. Such a procedure is based on both the characteristics of the disturbances and the desired flight path; in particular, a specific performance index is applied to tune filters. In this way control laws are adapted to the flight condition and these lead to an optimal path-following. This research represents an upload of previous papers. It allows eliminating …

FLIGHT CONTROL RESEARCH LABORATORY UNMANNED AERIAL SYSTEM WIND SHEAR ON-LINE IDENTIFICATION

An algorithm to perform the on line identification of the wind shear components suitable for the UAS characteristics has been implemented. The mathematical model of aircraft and wind shear in the augmented state space has been built without any restrictive assumption on the dynamic of wind shear. Because of the strong velocity variations typical of wind shear induce severe accelerations on the aircraft the wind shear effects have been modeled as external forces and moments applied on the aircraft. The identification problem addressed in this work has been solved by using the Filter error method approach. An Extended Kalman Filter has been developed to propagate state. It has been tuned by u…

An experimental investigation on air quality inside WindJet aircraft

ABSTRACT In order to improve the passengers and crew comfort during the flight, the aim of the present paper is a study of the cabin air quality through experimental measures on randomly selected flight segments of an Italian airline company, WindJet. Carbon dioxide, ultrafine particles, temperature and relative humidity have been measured by using low cost high efficiency instrumental equipments. Exploring ways to improve aircraft cabin air quality, WindJet and University of Palermo are investigating equipment, filters and components of the ventilation system. In this paper, after description of both ventilation systems for aircrafts of WindJet and the instrumental equipments used to measu…

Collision Avoidance Problem for an Ekranoplan

Numerical simulations of the aerodynamics characteristics for a non-conventional unmanned WIG.

In this paper we present our research about a particular ultralight WIG. WIG is the acronym of Wing In Ground effect vehicle. This work is part of a research on the dynamic behaviour for an UAV-WIG with a particular Tandem – Canard arrangement, study which the authors have been carrying out from several years. In previous paper the same Authors built a general mathematical model which permit to obtain analytical equations for all the aerodynamic coefficients both Out of Ground Effect and In Ground Effect conditions. In this paper, a numerical validation of the above mentioned mathematical model is proposed by the application of CFD methods. The mesh has been generated using ICEM 10.0 and th…

Automatic Take Off and Landing for UAS Flying in Turbulent Air - An EKF Based Procedure

An innovative use of the Extended Kalman Filter (EKF) is proposed to perform automatic take off and landing by the rejection of disturbances due to turbulence. By using two simultaneously working Extended Kalman Filters, a procedure is implemented: the first filter, by using measurements gathered in turbulent air, estimates wind components; the second one, by using the estimated disturbances, obtains command laws that are able to reject disturbances. The fundamental innovation of such a procedure consists in the fact that the covariance matrices of process (Q) and measurement (R) noise are not treated as filter design parameters. In this way determined optimal values of the aforementioned m…

A Feasibility Analysis For Wig’s As A Civil Transport System In The Mediterranean Sea

TAKEOFF AND LANDING ROBUST CONTROL SYSTEM FOR A TANDEM CANARD UAV

In spite of modern wide improvements in UAV’s technologies, a few number of such a vehicles is fully autonomous from takeoff to landing . So, either autonomous operation or operation with minimal human intervention is, actually, the primary design goal for the UAV’s researchers. The core of the problem is the design of the landing and takeoff control system. The objective of this paper is to design a control system in which the same state variables are controlled during both the descending/ascending path and the flare, tacking into account the actual ground effect. Robust control techniques are employed with the aim to cope with atmospheric turbulence, measurement noise, parameter variation…

Gain scheduling automatic landing system by modeling Ground Effect

Taking ground effect into account a longitudinal automatic landing system is designed. Such a system will be tested and implemented on board by using the Preceptor N3 Ultrapup aircraft which is used as technological demonstrator of new control navigation and guidance algorithms in the context of the “Research Project of National Interest” (PRIN 2008) by the Universities of Bologna, Palermo, Ferrara and the Second University of Naples. A general mathematical model of the studied aircraft has been built to obtain non–linear analytical equations for aerodynamic coefficients both Out of Ground Effect and In Ground Effect. To cope with the strong variations of aerodynamic coefficients In Ground …

An Extended Kalman Filter-Based Technique for On-Line Identification of Unmanned Aerial System Parameters

ABSTRACT: The present article deals with the identification, at the same time, of aircraft stability and control parameters taking into account dynamic damping derivatives. Such derivatives, due to the rate of change of the angle of attack, are usually neglected. So the damping characteristics of aircraft dynamics are attributed only on pitch rate derivatives. To cope with the dynamic effects of these derivatives, authors developed devoted procedures to estimate them. In the present paper, a complete model of aerodynamic coefficients has been tuned-up to identify simultaneously the whole set of derivatives. Besides, in spite of the employed reduced order model and/or decoupled dynamics, a s…

State Estimation of a Nonlinear Unmanned Aerial Vehicle Model using an Extended Kalman Filter