Nowadays, unmanned aerial vehicles (UAVs) represent a research field that is continuously expanding, due to their vast applications and economic advantages both in commercial and military cases: parcel delivery, aerial photography, search and rescue, reconnaissance and inspection are just some examples. The most common multi-rotor configuration has been studied in detail and has shown its limitation in terms of fight endurance: one of the solution implemented in order to overcome this limit is the combination with the fixed-wing configuration. This is the case of VTOL (Vertical Take Off and Landing) UAVs, that combine the ability to hover, take-off and land vertically, with a high efficiency and long endurance and range typical of conventional fixed-wing aircraft. The main purpose of this thesis is to fly an electric VTOL (eVTOL) designed and built in two previous master thesis within the Aerospace Systems and Control Laboratory (ASCL) of Politecnico di Milano. The result is a vehicle capable of both vertical and forward fight, with a take-off mass of around 6 kg, wing span of 2.25 m and an expected fight time of about 100 minutes. It is the first one to be completely designed and produced inside the Department of Aerospace Science and Technology (DAER) long since. In details, during the thesis some initial hardware problems have been solved, mainly related to the propulsion system; then the control system for the different flight phases (multirotor, transition and fixed-wing) has been implemented. The Simulink model of the vehicle developed in the past works has been improved and the control module has been added, allowing to simulate all the different flight modes of the drone: vertical flight, transition and forward flight. Then, the controllers have been installed on the eVTOL: the multi-rotor configuration has been successfully tested in flight, allowing to perform an identification campaign. The identified model has then been included in the flight simulator and compared to the previous analytical model, validating both with respect to a real flight. The transition and the forward flight have been successfully tested in simulation, but a complete flight test has not performed yet; only preliminary ground tests have been done: these experiments have confirmed the proper functioning of the controller and the results obtained in simulation, giving the green light to proceed with full flight tests.
Oggigiorno, i velivoli a pilotaggio remoto (APR o UAV - Unmanned Aerial Vehicles - in inglese) rappresentano un campo di ricerca in continua crescita ed espansione, grazie ai numerosi casi applicativi e vantaggi economici sia in campo civile che militare: consegna di pacchi, riprese aeree, ricerca e soccorso, ricognizione e ispezione sono solo alcuni esempi. La maggiormente diffusa configurazione multi rotore è stata studiata approfonditamente e ha mostrato la sua limitazione per quanto riguarda il tempo di volo; una delle strategie ideate per superare questa limitazione è l'unione con la configurazione ala fissa. Si parla in questo caso di droni VTOL (dall'inglese Vertical Take Off and Landing) in grado di combinare il decollo, l'atterraggio verticale e la capacità di hover con un'elevata efficienza e conseguenti lunghe distanze e tempi in volo tipici di velivoli convenzionali ad ala fissa. L'obiettivo principale di questa tesi è portare in volo un drone VTOL elettrico (eVTOL), progettato e costruito durante due precedenti tesi magistrali all'interno del Laboratorio di Sistemi e Controllo Aerospaziale (Aerospace System and Control Laboratory, ASCL) del Politecnico di Milano. Il risultato è un velivolo in grado di svolgere missioni sia in volo verticale che in volo avanzato; ha una massa al decollo di circa 6 kg, apertura alare di 2,25 m e un tempo di volo stimato di circa 100 minuti. É il primo ad essere completamente progettato e costruito all'interno del Dipartimento di Scienze e Tecnologie Aerospaziali (Department of Aerospace Science and Technology, DAER) dopo molto tempo. Nel dettaglio, durante la tesi sono stati risolti alcuni iniziali problemi hardware legati principalmente al sistema propulsivo; è poi stato progettato il sistema di controllo per le diverse fasi di volo: multi rotore, transizione e volo in modalità ala fissa. Il modello Simulink del velivolo sviluppato nei precedenti lavori è stato migliorato e il modulo di controllo è stato aggiunto, permettendo di simulare una missione completa: decollo, salita verticale, transizione al volo avanzato e volo avanzato. I controllori sviluppati sono poi stati installati a bordo dell'eVTOL per il test in volo, integrandosi nell'autopilota open-source PX4: la configurazione multirotore è stata testata con successo in volo, permettendo poi di eseguire una campagna di identificazione del modello. Il modello identificato è stato poi inserito nel simulatore e comparato al precedente modello analitico, validando entrambi rispetto ad una missione realmente volata. La transizione e il volo avanzato invece sono stati testati con successo in simulazione, ma non è ancora stata eseguita una prova completa in volo; sono stati infatti effettuati solo test preliminari a terra: questi esperimenti hanno confermato il corretto funzionamento del controllore e i risultati ottenuti in simulazione, dando il via libera per procedere con le prove di volo complete.
Modelling, control, integration and testing of an eVTOL drone
Martinelli, Elia
2021/2022
Abstract
Nowadays, unmanned aerial vehicles (UAVs) represent a research field that is continuously expanding, due to their vast applications and economic advantages both in commercial and military cases: parcel delivery, aerial photography, search and rescue, reconnaissance and inspection are just some examples. The most common multi-rotor configuration has been studied in detail and has shown its limitation in terms of fight endurance: one of the solution implemented in order to overcome this limit is the combination with the fixed-wing configuration. This is the case of VTOL (Vertical Take Off and Landing) UAVs, that combine the ability to hover, take-off and land vertically, with a high efficiency and long endurance and range typical of conventional fixed-wing aircraft. The main purpose of this thesis is to fly an electric VTOL (eVTOL) designed and built in two previous master thesis within the Aerospace Systems and Control Laboratory (ASCL) of Politecnico di Milano. The result is a vehicle capable of both vertical and forward fight, with a take-off mass of around 6 kg, wing span of 2.25 m and an expected fight time of about 100 minutes. It is the first one to be completely designed and produced inside the Department of Aerospace Science and Technology (DAER) long since. In details, during the thesis some initial hardware problems have been solved, mainly related to the propulsion system; then the control system for the different flight phases (multirotor, transition and fixed-wing) has been implemented. The Simulink model of the vehicle developed in the past works has been improved and the control module has been added, allowing to simulate all the different flight modes of the drone: vertical flight, transition and forward flight. Then, the controllers have been installed on the eVTOL: the multi-rotor configuration has been successfully tested in flight, allowing to perform an identification campaign. The identified model has then been included in the flight simulator and compared to the previous analytical model, validating both with respect to a real flight. The transition and the forward flight have been successfully tested in simulation, but a complete flight test has not performed yet; only preliminary ground tests have been done: these experiments have confirmed the proper functioning of the controller and the results obtained in simulation, giving the green light to proceed with full flight tests.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/190621