Marilena Pavel

Delft University of Technology | TU · Department of Control and Operations (C&O)

The health management of batteries is a key enabler for the adoption of Electric Vertical Take-off and Landing vehicles (eVTOLs). Currently, few studies consider the health management of eVTOL batteries. One distinct characteristic of batteries for eVTOLs is that the discharge rates are significantly larger during take-off and landing, compared wit...

The power required to hover a helicopter is fundamental to any new or modified performance flight-testing effort. The conventional method of relating two nondimensional variables (coefficients of power and weight) is overly simplified and neglects compressibility effects in the power required to hover under a wide range of gross weights and atmosph...

This paper investigates the effects of different automation design philosophies for a helicopter navigation task. A baseline navigation display is compared with two more advanced systems: an advisory display, which provides a discrete trajectory suggestion; and a constraint-based display, which provides information about the set of possible traject...

This paper analyzes the effects of the helicopter dynamics on pilots’ learning process and transfer of learned skills during autorotation training. A quasi-transfer-of-training experiment was performed with 14 experienced helicopter pilots in a moving-base flight simulator. Two types of helicopter dynamics, characterized by a different autorotative...

Training has the potential to inject a "safety vaccination" into the rotorcraft community by reducing the number of accidents. The term training should not be intended only in a strict sense, i.e., as pilot technical skills training, but more broadly as risk avoidance and safety culture training. As in the case of vaccination , where immunity is cr...

The research presented in this paper focuses on the development of a quasi-Linear Parameter Varying (qLPV) model for the XV-15 tiltrotor aircraft. The specific category of qLPV modeling technique, known as the model stitching technique, is employed to model the time-varying dynamics of XV-15 tiltrotor aircraft over the entire flight envelope. In th...

The aim of the present paper is to present an understanding of the control characteristics for representative eVTOL (Electric Vertical Takeoff and Landing) quadcopters having the same properties of interest as the eVTOL configurations developed presently in Urban Air Mobility. In this context, the paper concentrates on eVTOL quadcopters with pure r...

Eigenmode distortion is a novel quantitative methodology developed to objectively evaluate motion cueing fidelity in flight simulation. It relies on an explicit coupling of linearized vehicle and Motion Cueing Algorithm dynamics. Modal analysis subsequently performed on this coupled system reveals the degree of distortion imposed by the Motion Cuei...

This paper investigates the effect of employing different display design principles for human–machine interaction in helicopters. Two obstacle avoidance support displays are evaluated during low-altitude forward flight. A baseline head-up display is complemented either by a conventional advisory display or a constraint-based display inspired by eco...

Reinforcement learning is an appealing approach for adaptive, fault-tolerant flight control, but is generally plagued by its need for accurate system models and lengthy offline training phases. The novel Incremental Dual Heuristic Programming (IDHP) method removes these dependencies by using an online-identified local system model. A recent impleme...

The process of empirical models evaluation is at the core business of experimental flight-testing data analysis. Accurate and convenient flight-testing of helicopter engine(s) available power is crucial for predicting the total helicopter performance. Common practice in estimation of in-flight helicopter gas turbine engine power consists of a reduc...

Incremental nonlinear dynamic inversion (INDI)-based controller is a promising technique that can be adopted to control dynamic systems with high nonlinearities and extended cross-coupling effects. This paper presents the incremental strategy adopted as a sensor-based controller approach for the Apache AH-64D Longbow helicopter. The strength of the...

Head-down hover displays and instrument panels theoretically provide all necessary flight data information to control low-speed helicopter manoeuvring. However, past experiments have shown that head-down displays can incur high workload, control instability, and even loss of control when used as the sole flight data source. This paper investigates...

Autorotation is a flight condition whereby the engine of a helicopter is no longer supplying power to the main rotor system, which is driven solely by the upward flow of the air moving through the rotor. For helicopters, autorotation is a common emergency procedure performed by pilots to safely land the vehicle in the event of a power failure or ta...

A safe conversion of tiltrotor from helicopter mode to airplane mode is ensured through maneuvering within the conversion corridor, a constrained region in the airspeed versus nacelle angle graph. This paper presents preliminary work in the development of an automatic conversion maneuver. A high order quasi-Linear Parameter Varying model is develop...

Despite significant interest in tailless flapping-wing micro aerial vehicle designs, tailed configurations are often favoured, as they offer many benefits, such as static stability and a simpler control strategy, separating wing and tail control. However, the tail aerodynamics are highly complex due to the interaction between the unsteady wing wake...

With the increasing amount of wind energy produced by wind turbines both on land and offshore, together with the close interaction of helicopter flight in the direct vicinity of a wind turbine (park), the need to investigate the interrelation between the wind turbine wake and the effect on helicopter handling and therefor safety and the influence o...

With the increasing amount of wind energy produced by wind turbines both on land and offshore, together with the close interaction of helicopter flight in the direct vicinity of a wind turbine (park), the need to investigate the interrelation between the wind turbine wake and the effect on helicopter handling and therefor safety and the influence o...

With the increasing amount of wind energy produced by wind turbines both on land and offshore, together with the close interaction of helicopter flight in the direct vicinity of a wind turbine (park), the need to investigate the interrelation between the wind turbine wake and the effect on helicopter handling and therefor safety and the influence o...

With the increasing amount of wind energy produced by wind turbines both on land and offshore, together with the close interaction of helicopter flight in the direct vicinity of a wind turbine (park), the need to investigate the interrelation between the wind turbine wake and the effect on helicopter handling and therefor safety and the influence o...

With the increasing amount of wind energy produced by wind turbines both on land and offshore, together with the close interaction of helicopter flight in the direct vicinity of a wind turbine (park), the need to investigate the interrelation between the wind turbine wake and the effect on helicopter handling and therefor safety and the influence o...

With the increasing amount of wind energy produced by wind turbines both on land and offshore, together with the close interaction of helicopter flight in the direct vicinity of a wind turbine (park), the need to investigate the interrelation between the wind turbine wake and the effect on helicopter handling and therefor safety and the influence o...

Today, simulators are achieving levels of complexity and cost that are comparable to those of the aircraft they should replace. For this reason, questions have been raised, in both the technical and training communities , on the required level of simulation delity for effective pilot training. Computer Based Trainers (CBTs) are not currently consid...

The accident rate of rotorcraft has improved signicantly over the years but at a slow pace, and in any case the number of accidents per ight hours is one or two orders of magnitude higher than that of commercial aircraft, a consideration that could be reasonably related to the inherent higher risk associate with rotor-craft operations. This represe...

The SABRE project has been initiated under the EU's Horizon programme for development of blade morphing technologies for helicopter rotors. The project targets reductions in fuel burn and NOx emissions of upto-% through the use of morphing rotor blades. A new design tool for rotorcraft, HOPLITE, is being developed to investigate the effects of roto...

Eigenmode distortion (EMD) is a novel methodology developed to study the degradation of perceived vehicle dynamics as a result of motion cueing algorithms (MCA's) applied in rotorcraft flight simulators. This paper briefly introduces EMD and subsequently describes its application in a pilot-in-the-loop experiment conducted on the SIMONA Research Si...

Nowadays, the complexity of high speed civil transport and highly-augmented rotorcraft, has led to an increase in the chances of encountering unwanted unstable phenomena, such as the so called Aircraft/Rotorcraft-Pilot Couplings (A/RPCs) or Pilot-Induced Oscillations (PIOs), whose unpredictability has given rise to a serious problem concerning the...

The effects of a wind turbine wake on General Aviation and the behaviour of helicopters in the tip vortex of large fixed-wing aircraft has been topic of research in the past years, but less is known about the interactions of helicopters operating in a wind turbine wake. A dedicated GARTEUR Action Group, HC-AG23, consisting of European universities...

Helicopters are currently used in important applications providing a valuable contribution to society and economic growth. Thanks to their operational flexibility it is possible to accomplish increasingly complex missions. If the expansion of the usage of rotorcraft is to follow the pace of growth achieved by the fixed-wing public transport in the...

The paper investigates the basic mechanism of aeroservoelastic pilot-assisted oscillation about the roll axis due to the interaction with pilot’s arm biomechanics. The motivation stems from the observation that a rotor imbalance May occur as a consequence of rotor cyclic lead–lag modes excitation. The work shows that the instability mechanism is an...

Helicopter performance relies heavily on the available output power of the engine(s) installed. A simplistic single-variable analysis approach is often used within the flight-testing community to reduce flight-test data in order to predict the available output power under various atmospheric conditions. This simplistic approach often results in unr...

In search of a more objective way to evaluate motion cueing fidelity, the Objective Motion Cueing Test (OMCT) was proposed by Advani and Hosman in 2006. However, a direct application of this test for rotorcraft flight simulation has not yet been studied. The first objective of this paper is therefore to investigate the extent to which the OMCT is r...

The fidelity of a rotorcraft flight simulator is influenced by many factors, such as the vehicle dynamic model and the motion cueing algorithm (MCA). To quantify the fidelity of a simulator objectively requires detailed knowledge of human pilot perception and control behaviour that is not yet available. As a consequence, subjective assessments made...

The paper reassesses the mechanism of biodynamical feedthrough coupling to helicopter body motion in lateral-roll helicopter tasks. An analytical bio-aeroelastic pilot–vehicle model is first developed and tested for various pilot's neuromuscular adaptions in the lateral/roll axis helicopter tasks. The results demonstrate that pilot can destabilize...

The Ornicopter concept is a single-rotor, tailless configuration. By actively flapping its blades, the Ornicopter rotor can propel itself to rotate, and hence does not need a tail rotor. In previous research, the Ornicopter concept has been compared with the Bo-105 conventional helicopter from various aspects, while the Ornicopter has the same desi...

Among the many fundamental components of a flight simulator, the mathematical representation of the vehicle dynamics stands out for complexity and importance. This is especially true for helicopters, for which the complex dynamics involved prevents simple models to be sufficiently accurate without the need of a certain amount of artificial tuning....

Abstract The aviation community relies heavily on flight simulators as a fundamental tool for research, pilot training and development of any new aircraft design. The goal of the present paper is to provide a review on how effective ground simulation is as an assessment tool for unmasking adverse Aircraft-and-Rotorcraft Pilot Couplings (APC/RPC). A...

Understanding, predicting and supressing the inadvertent aircraft oscillations caused by Aircraft/Rotorcraft Pilot Couplings (A/RPC) is a challenging problem for designers. These are potential instabilities that arise from the effort of controlling aircraft with high response actuation systems. The present paper reviews, updates and discusses desir...

This paper introduces a new approach for the identification of linear state-space models of dynamical systems of arbitrary complexity. The identification procedure is described and applied for modeling aeroelastic response of helicopter main rotors. With the aim of developing a tool that might be conveniently applied for real-time simulations of he...

The 'Ornicopter' is a single-rotor helicopter without anti-torque rotor developed since 2002 at Delft University of Technology in The Netherlands. The Ornicopter's principle is similar to the movement of a bird's wing and is based on actively flapping the blades up and down while rotating them around a shaft to generate both the required lift and t...

A computational platform is presented that aims to optimize helicopter trajectories with respect to the noise impact in near-heliport communities under varying atmospheric conditions. The software suite is based on a fast gradient-based optimization algorithm which is linked to a rigid-body helicopter flight mechanics model to model the free motion...

Previous investigators have found that obtaining the same results using different simulation facilities for notionally identical test can be difficult to achieve. This was also found to be true in the EC-Framework 7-funded ARISTOTEL project. This project used two simulators in parallel - the HELIFLIGHT-R Simulator (HFR) at the University of Liverpo...

Biodynamic feedthrough (BDFT) occurs when vehicle accelerations feed through the pilot’s body and cause involuntary motions of limbs, resulting in involuntary control inputs. BDFT can severely reduce ride comfort, control accuracy and, above all, safety during the operation of rotorcraft. Furthermore, BDFT can cause and sustain rotorcraft-pilot cou...

Fixed and rotary wing pilots alike are familiar with potential instabilities or with annoying limit cycle oscillations that arise from the effort of controlling aircraft with high response actuation systems. Understanding, predicting and suppressing these inadvertent and sustained aircraft oscillations, known as aircraft (rotorcraft)-pilot coupling...

Fixed and rotary wing pilots alike are familiar with potential instabilities or with annoying limit cycle oscillations that arise from the effort of controlling aircraft with high response actuation systems. Understanding, predicting and supressing these inadvertent and sustained aircraft oscillations, known as Aircraft (Rotorcraft)-Pilot Couplings...

Unfavourable Aircraft/Rotorcraft Pilot Couplings (A/RPCs), usually called pilot induced oscillations (PIO), manifested themselves since the early days of manned flight and may still create problems in modern configurations. In Europe, the ARISTOTEL project (Aircraft and Rotorcraft Pilot Couplings - Tools and Techniques for Alleviation and Detection...

Due to the inherent instabilities and nonlinearities of rotorcraft dynamics, its changing properties during flight and the engineering difficulties to predict its aerodynamics with high levels of fidelity, helicopter flight control requires the application of special strategies. These strategies must allow to cope with the nonlinearities of the sys...

The paper presents an energetic method of helicopters dynamics analysis to study the air resonance (AR) phenomena. First, a brief state of art of AR phenomena is presented and a simple energetic explanation is given. Then part of the state of art is devoted to the Bond Graph (BG) and Multi-Bond Graphs (MBG) modeling method showing several advantage...

At the heart of a flight simulator resides the mathematical representation of aircraft behaviour in response to control inputs, atmospheric disturbances and system inputs including failures and malfunctions. While this mathematical model can never be wholly accurate, its fidelity, in comparison with real world behaviour, underpins the usefulness of...

At the heart of a flight simulator resides the mathematical representation of aircraft behaviour in response to control inputs, atmospheric disturbances and system inputs including failures and malfunctions. While this mathematical model can never be wholly accurate, its fidelity, in comparison with real world behaviour, underpins the usefulness of...

The aim of this study is to assess the load predicting capability of a classical Beddoes–Leishman dynamic stall model in a horizontal axis wind turbine environment, in the presence of yaw misalignment. The dynamic stall model was tailored to the horizontal axis wind turbine environment and validated against unsteady thick airfoil data. Subsequently...

The goal of the present paper is to investigate the pilot control behaviour during "possible" Rotorcraft Pilot Coupling (RPC) events. Two identification experiments were conducted in two simulation facilities with four helicopter pilots and eight human subjects. Both experiments used a single loop roll disturbance-rejection hover task, with a time...

A software suite is presented that aims to optimize rotorcraft trajectories with respect to the environmental impact on the human environment, with a strong emphasis on noise abatement. To model the asymmetrical noise characteristics of rotorcraft, a source noise database is used, which is calculated offline. The propagation model, integrated in th...

Qualification programs to define ship helicopter operational limitations are based on a large number of independent variables causing the full operational potential to be almost impossible to achieve within the small window normally allowed for sea trials. It would be a clear advantage to have a predictive engineering tool to perform early evaluati...

Fixed and rotary wing pilots alike are familiar with potential instabilities or with annoying limit cycle oscillations that arise from the effort of controlling aircraft with high response actuation systems. Understanding, predicting and suppressing these inadvertent and sustained aircraft oscillations, known as Aircraft (Rotorcraft)-Pilot Coupling...

Biodynamic feedthrough (BDFT) occurs when vehicle accelerations feed through the pilot's body and cause involuntary motions of limbs, resulting in involuntary control inputs. BDFT can severely reduce ride comfort, control accuracy and, above all, safety during the operation of rotorcraft. Furthermore, BDFT can cause and sustain rotorcraft-pilot cou...

This paper describes the application of the newly developed Phase-Aggression Criterion to data obtained during a simulated flight test campaign, in order to assess its suitability to detect Rotorcraft Pilot Coupling events. Due to the increasing complexity of modern rotorcraft, both the frequency and severity of Rotorcraft Pilot Coupling events is...

This paper introduces an improvement of existing Real-Time Oscillation VERifier (ROVER) by including rotorcraft handling qualities (HQ) assessment to achieve enhanced Rotorcraft Pilot Coupling (RPC) detection. First, the classical ROVER algorithm was implemented. Then, it was tested on desktop simulations. Next, it was evaluated by post hoc analysi...

Rotorcraft (helicopters and tiltrotors) are generally reliable flying machines capable of fulfilling missions impossible with fixed-wing aircraft, most notably rescue operations. These missions, however, often lead to high and sometimes excessive pilot workload. Although high standards in terms of safety are imposed in helicopter design, studies sh...

Fixed and rotary wing pilots alike are familiar with potential instabilities or with annoying limit cycle oscillations that arise from the effort of controlling aircraft with high response actuation systems. Understanding, predicting and supressing these inadvertent and sustained aircraft oscillations, known as Aircraft (Rotorcraft)-Pilot Couplings...

Biodynamic feedthrough (BDFT) refers to a phenomenon where vehicle accelerations cause involuntary pilot limb motions which, when coupled to a control device, can result in unintentional control inputs. It is known that BDFT occurs in helicopters, amongst many other vehicles. The goal of the current study is to analyze the pilot's response to helic...

At the Delft University of Technology, an optimization framework is under development to optimize rotorcraft trajectories with respect to environmental and operational criteria. The new optimization framework comprises a dynamic trajectory optimization algorithm, a rotorcraft flight dynamics model, a geographic information system, a noise model and...

The Ornicopter is a relatively new concept of tailless helicopter. By actively flapping the blades up and down, similar to the movement of a bird's wing, the blades will propel themselves around the rotor shaft and will at the same time provide a lifting force. Because of the propulsive force, the rotor blades will rotate themselves and the shaft t...

Rotary wing aircraft and especially helicopters are relatively slow machines that normally fly at altitudes below 3000 m. The continual advances in the fields of smart rotor design, lightweight structures and integrated flight management and avionics systems, alongside improvements of the fuselage aerodynamics and the advances recorded in engine ef...