Nowadays, the complexity of high-speed civil transport and highly augmented rotorcraft has led to an increase in the chances of encountering adverse pilot-vehicle system (PVS) interactions, such as the so-called aircraft/rotorcraft-pilot couplings (A/RPCs), whose unpredictability is a serious problem for mission safety. To better understand the causes that can lead to PVS interactions for advanced helicopter configurations, modelling and simulation techniques for the prediction and real-time detection of adverse A/RPC events have been used, explored, and enhanced through the study reported in this thesis. First of all, the phase-aggression criterion (PAC) has been developed as a parameter to indicate the presence of A/RPC events in real-time, this can be linked to a head-up display for alerting the pilot that they are in, or about to enter, an A/RPC. Moreover, atmospheric turbulence and swashplate actuator rate limits have been included in the simulations to stimulate the onset of A/RPC events and to assess its effect on pilot workload. Lastly, to enable objective and quantitative comparisons of human behaviour during adverse PVS interactions, the cybernetic approach with its pilot modelling techniques has been used for identification of manual control behaviour and adaptation to variations in aircraft dynamics. Hence, the results of this research contribute towards the facilitation of unmasking and objectively detecting in real-time unstable phenomena due to unwanted interactions between aircraft/rotorcraft and pilot. One key research question to be answered through the efforts carried out within this work is “How can one better detect in real-time embedded tendencies to A/RPCs in modern aircraft?” To answer this question, initially, an assessment of the efficacy of the PAC has been undertaken both as a means of alerting the pilot to conditions likely to lead to the onset of a pilot-induced oscillation (PIO), and as a means to assist the pilot in alleviating the PIO condition itself. Results from flight simulation trials to explore how best to achieve this have been reported. Objective and subjective measures, designed in past research projects to reduce the A/RPC susceptibility in rotorcraft, were used to develop and implement a novel real-time detection tool useful for piloted simulated (and potentially real) flights, along with a warning system able to provide useful cues to the pilot. Pilot-in-the-loop experiments, in which different test pilots participated, were run inside the University of Liverpool’s and Delft University of Technology’s flight simulation facilities. The purpose of these piloted simulation test campaigns was not only to develop, test and validate a real-time detection system to alleviate and/or reduce the presence of A/RPCs, but also to perform an objective estimation of human control behaviour and adaptation to changes in the controlled aircraft dynamics. The research reported in this thesis contributes to enlarging the state-of-the-art and the know-how in relation to adverse pilot-vehicle interactions, such as A/RPC events, with the aim of preventing their incipience, or detecting and alleviating them, prior to catastrophic occurrences, through the use of novel tools which can be implemented in the aircraft/ rotorcraft. Overall, the results show a good correlation between objective and subjective evaluations, and that it is possible to detect PIOs in real-time and provide a timely indication of the PIO and its severity to the pilot. Furthermore, a significant effect of turbulence on A/RPCs incipience and pilot workload is observed. Finally, the results from the cybernetic approach show consistent adaptation of manual control behaviour to variations in both short-period parameters and a worsening of task performance with decreased short-period natural frequency and decreased damping ratio settings.
Al giorno d’oggi, la complessità del trasporto civile ad alta velocità e dei velivoli ad ala rotante altamente potenziati ha portato ad un aumento delle probabilità di incontrare interazioni avverse nel sistema pilota-veicolo (PVS), come i cosiddetti accoppiamenti tra aeromobile/elicottero e pilota (A/RPC), la cui imprevedibilità rappresenta un grave problema per la sicurezza delle missioni. Per comprendere meglio le cause che possono portare a interazioni PVS avverse per configurazioni avanzate di elicotteri, attraverso lo studio riportato in questa tesi, sono state utilizzate, esplorate e migliorate tecniche di modellizzazione e simulazione per la previsione e la rilevazione in tempo reale di eventi avversi A/RPC. Innanzitutto, il criterio di fase-aggressione (PAC) è stato sviluppato come parametro per indicare la presenza di eventi A/RPC in tempo reale, questo può essere collegato ad un head-up display per avvisare il pilota che si trova in una situazione di A/RPC o sta per entrarvi. Inoltre, turbolenza atmosferica e limiti di velocità dell’attuatore del piatto oscillante dell’elicottero sono stati inclusi nelle simulazioni per stimolare l’insorgenza di eventi A/RPC e valutarne l’effetto sul carico di lavoro del pilota. Infine, per consentire confronti obiettivi e quantitativi del comportamento umano durante le interazioni PVS avverse, è stato utilizzato l’approccio cibernetico con le relative tecniche di modellizzazione del pilota per l’identificazione del comportamento di controllo manuale e l’adattamento alle variazioni nella dinamica del velivolo. Dunque, i risultati di questa ricerca contribuiscono a facilitare l’individuazione oggettiva e in tempo reale di fenomeni instabili dovuti ad interazioni indesiderate tra velivolo e pilota. Uno dei principali quesiti di ricerca su cui è incentrato questo lavoro è “Come si può migliorare la rilevazione in tempo reale delle tendenze incorporate agli A/RPC negli aeromobili moderni?” Per rispondere a questa domanda, inizialmente è stata effettuata una valutazione sull’efficacia del PAC sia come mezzo per avvertire il pilota delle condizioni che probabilmente porteranno all’inizio di un’oscillazione indotta dal pilota (PIO), sia come mezzo per aiutarlo/a ad alleviare la condizione di PIO stessa. I risultati dei test di simulazione di volo, condotti al fine di esplorare il modo migliore per raggiungere questo obiettivo, sono stati riportati in questa tesi. Misure oggettive e soggettive, ideate in progetti di ricerca passati per ridurre la suscettibilità di A/RPC negli elicotteri, sono state utilizzate per sviluppare e implementare uno strumento di rilevamento in tempo reale innovativo utile per voli simulati pilotati (e potenzialmente reali), insieme ad un sistema di avviso in grado di fornire indicazioni utili al pilota. Alcuni esperimenti pilot-in-the-loop, a cui hanno partecipato diversi piloti collaudatori, sono stati condotti all’interno delle strutture di simulazione di volo dell’Università di Liverpool e della Delft University of Technology. Lo scopo di queste campagne di test di simulazione pilotata non era solo quello di sviluppare, testare e convalidare un sistema di rilevamento in tempo reale per alleviare e/o ridurre la presenza di A/RPC, ma anche di effettuare una stima obiettiva del comportamento di controllo umano e dell’adattamento alle variazioni nella dinamica del velivolo controllato. La ricerca riportata in questa tesi contribuisce ad ampliare lo stato dell’arte e il knowhow in relazione alle interazioni avverse tra pilota e veicolo, come i fenomeni A/RPC; l’obiettivo è di prevenirne l’incipienza o rilevarla e alleviarla, prima di eventi catastrofici, attraverso l’uso di nuovi strumenti che possono essere implementati nell’aeromobile/elicottero. Nel complesso, i risultati mostrano una buona correlazione tra valutazioni oggettive e soggettive, e che è possibile rilevare PIO in tempo reale e fornire tempestivamente l’indicazione della loro intensità al pilota. Inoltre, la ricerca evidenzia un effetto significativo della turbolenza sull’incipienza di A/RPC e sul carico di lavoro del pilota. Infine, i risultati riguardanti l’approccio cibernetico mostrano un peggioramento delle prestazioni in relazione ad una diminuzione della frequenza naturale e del rapporto di smorzamento di corto periodo, ed un costante adattamento del comportamento di controllo manuale del pilota alle variazioni di entrambi i parametri di corto periodo.
Development of novel methods for the prediction and real-time detection of adverse pilot-vehicle interactions
Fasiello, Simone
2023/2024
Abstract
Nowadays, the complexity of high-speed civil transport and highly augmented rotorcraft has led to an increase in the chances of encountering adverse pilot-vehicle system (PVS) interactions, such as the so-called aircraft/rotorcraft-pilot couplings (A/RPCs), whose unpredictability is a serious problem for mission safety. To better understand the causes that can lead to PVS interactions for advanced helicopter configurations, modelling and simulation techniques for the prediction and real-time detection of adverse A/RPC events have been used, explored, and enhanced through the study reported in this thesis. First of all, the phase-aggression criterion (PAC) has been developed as a parameter to indicate the presence of A/RPC events in real-time, this can be linked to a head-up display for alerting the pilot that they are in, or about to enter, an A/RPC. Moreover, atmospheric turbulence and swashplate actuator rate limits have been included in the simulations to stimulate the onset of A/RPC events and to assess its effect on pilot workload. Lastly, to enable objective and quantitative comparisons of human behaviour during adverse PVS interactions, the cybernetic approach with its pilot modelling techniques has been used for identification of manual control behaviour and adaptation to variations in aircraft dynamics. Hence, the results of this research contribute towards the facilitation of unmasking and objectively detecting in real-time unstable phenomena due to unwanted interactions between aircraft/rotorcraft and pilot. One key research question to be answered through the efforts carried out within this work is “How can one better detect in real-time embedded tendencies to A/RPCs in modern aircraft?” To answer this question, initially, an assessment of the efficacy of the PAC has been undertaken both as a means of alerting the pilot to conditions likely to lead to the onset of a pilot-induced oscillation (PIO), and as a means to assist the pilot in alleviating the PIO condition itself. Results from flight simulation trials to explore how best to achieve this have been reported. Objective and subjective measures, designed in past research projects to reduce the A/RPC susceptibility in rotorcraft, were used to develop and implement a novel real-time detection tool useful for piloted simulated (and potentially real) flights, along with a warning system able to provide useful cues to the pilot. Pilot-in-the-loop experiments, in which different test pilots participated, were run inside the University of Liverpool’s and Delft University of Technology’s flight simulation facilities. The purpose of these piloted simulation test campaigns was not only to develop, test and validate a real-time detection system to alleviate and/or reduce the presence of A/RPCs, but also to perform an objective estimation of human control behaviour and adaptation to changes in the controlled aircraft dynamics. The research reported in this thesis contributes to enlarging the state-of-the-art and the know-how in relation to adverse pilot-vehicle interactions, such as A/RPC events, with the aim of preventing their incipience, or detecting and alleviating them, prior to catastrophic occurrences, through the use of novel tools which can be implemented in the aircraft/ rotorcraft. Overall, the results show a good correlation between objective and subjective evaluations, and that it is possible to detect PIOs in real-time and provide a timely indication of the PIO and its severity to the pilot. Furthermore, a significant effect of turbulence on A/RPCs incipience and pilot workload is observed. Finally, the results from the cybernetic approach show consistent adaptation of manual control behaviour to variations in both short-period parameters and a worsening of task performance with decreased short-period natural frequency and decreased damping ratio settings.| File | Dimensione | Formato | |
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Descrizione: PhD Thesis
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https://hdl.handle.net/10589/229012