Exact Solutions of the Two Dimensional Boussinesq and Dispersive Water Waves Equations

In this paper two-dimensional Boussinesq and dispersive water waves equations are investigated in exact solutions. The Exp-function method is used for seeking exact solutions of the equations through symbolic computation.

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…

Critical features about urban pedestrian crossings: a case study

This paper describes how the theme of safety for vulnerable road users (disabled, elderly, and children) in urban areas plays an important role for many implications in these users’ quality of life. The deficiency of safety on city streets is primarily due to the simultaneous presence of different components of traffic in an increasingly complex and inappropriate surrounding for their cohabitation. In urban areas the road intersections, which are crossed by different categories of traffic (motorized vehicles, pedestrians, non-motorized vehicles), represent a critical node, both in terms of quality of circulation and that of road safety. In recent years , 76% of accidents have occurred in th…

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…

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…

Helicopter lines: demand & cost analysis

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…

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.

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…

Il mercato degli UAS: campi di applicazione

L'utilizzo di Unmanned Aerial Systems (UAS) ha avuto un incremento significativo negli ultimi anni. Il loro impiego, prima riservato ai soli fini militari, si è sempre più rivolto a campi prettamente civili quali, per esempio la sorveglianza, il controllo ambientale ed il rilievo aereo. Nel presente lavoro verrà esaminata dapprima l'evoluzione del campo degli UAS nel mondo, verranno esaminati e descritti i primi sviluppi ed utilizzi fino ai più recenti in modo da dare un panorama completo delle tecnologie in essere, focalizzando, in una seconda parte, l'attenzione su costruttori e sviluppatori sia europei che extraeuropei. Saranno inoltre approfonditi gli usi civili degli UAS che, negli ult…

TRAVELLING TOWARDS AND FROM MINOR ISLANDS THROUGH NON-CONVENTIONAL AIR TRANSPORT: DEMAND AND COST ANALYSIS

This research addresses the role of innovative forms of passenger air transport in favouring mobility of tourists visiting minor islands. In particular, we studied the feasibility of scheduled transport services using helicopter and seaplane for connecting Sicily in the south of Italy, to the near and very attractive Eolie Islands rapidly. In order to estimate the potential service demand, we allowed for the number of tourists arriving in the Eolie Archipelago during the period 1999-2008. In detail, we considered only the market of visitors with a high willingness-to-pay for time savings (individuals choosing superior hotels) coming from origins at least 300 km away from the Eolie Islands. …

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 …

Le isole minori quali poli di attrazione turistica ed i servizi elicotteristici di linea in Sicilia

La continua esigenza di accorciare i tempi di viaggio, che, assieme alla spinta all’economicità delle tariffe, caratterizza fortemente la domanda passeggeri, spinge alla progettazione di sistemi di trasporto innovativi che permettano di ottenere prestazioni efficaci ed efficienti. I modi di trasporto provano a rispondere all’esigenza di garantire una pronta e adeguata copertura di mobilità e, d’altro canto, ad abbattere la difficoltà di riuscire a realizzare sistemi dinamici, che possano adattarsi nel tempo alle fluttuazioni della domanda. Tra i sistemi di trasporto pubblico quello elicotteristico non riveste attualmente un ruolo da protagonista all’interno della complessa struttura della m…

Collegamenti con aerei di tipo V/STOL: innovazioni tecnologiche, organizzative e di esercizio

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 …

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…

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…

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…