Matthew Marino

Dynamic Sensitivity to Atmospheric Turbulence of Unmanned Air Vehicles with Varying Configuration

DOI: 10.2514/1.46860 Air vehicle flight in turbulence is generally treated as an anomalous part of the flying environment. Aircraft geometries and flight-control systems are often designed and tested for calm atmospheric conditions, where both steady winds and gusts are minor. As a result, the flight performance of small aircraft deteriorates in the presence of atmospheric turbulence, where gust disturbances can be large relative to the flying speeds. A better approach is needed in the aircraft and control system design process that specifically accounts for the effects of turbulence and providesameansofmitigatingdisturbancestoimprovethemissioneffectivenessofmicrounmannedairvehiclesand small unmanned air vehicles. The current research considers untethered flight tests of a small unmanned air vehicle in a large wind engineering tunnel that can be configured to replicate turbulence levels expected from urban and suburban environments. Systematic changes to the configuration of the fixed-wing aircraft are made to evaluate the roleofmetrics,suchasc.g.,mass,momentofinertia,wingspan,andwingloadingtoturbulencesensitivity.Estimates of the force and moment disturbances indicate that some parameters, such as moment of inertia, have simple and expectedinfluencesontheresponsetoturbulence. Conversely,wingareaandmasshaveconflictingeffectsduetothe compounded influences on the aircraft response. The sensitivity of the various aircraft configurations to turbulence are presented as control equivalent turbulence disturbances, which equate forces and moments acting on the airframe to control deflections. This method normalizes the aircraft responses with respect to the ability to suppress disturbances with actuated controls.

Bioinspired Wing-Surface Pressure Sensing for Attitude Control of Micro Air Vehicles

Fixed-wing micro aerial vehicles experience attitude control difficulties as they operate in highly turbulent environments. Previous research has identified pressure-based control as a potential approach for augmenting the performance of, or replacing, autopilots reliant on inertial sensors. However, implementation requires an in-depth understanding of the correlation that exists between oncoming gusts and wing surface-pressure variations. This paper investigates the variation of correlation along a representative micro aerial vehicle wing chord and wingspan between upstream flow pitch angle variation and wing surface-pressure variation. Atmospheric turbulence was replicated within the controlled environment of a wind tunnel using planar grids that generated a turbulence intensity of 12.6%. Despite the unsteady nature of the pressure field, it was discovered that high correlation is evident in the vicinity of the leading edge. Thus, a few optimally placed sensors can be used for a pressure-based attitude ...

Influence of large-scale freestream turbulence on the performance of a thin airfoil

Micro air vehicles are typically small in size and are remotely controlled or autonomous aircraft that fly slowly (50; 000 < Reynolds number < 200; 000) and very close to the Earths surface. Due to the combined influences of low Reynolds number effects and the high levels of freestream turbulence, present within the atmospheric boundary layer, micro air vehicles are very difficult to control/fly outdoors.

An Evaluation of Multi-Rotor Unmanned Aircraft as Flying Wind Sensors

This paper examines the possibility of using a Multi-Rotor Unmanned Aircraft System (MUAS) for atmospheric flow measurements around a tall building. This novel sensing approach is proposed, whereby we attempt to determine the oncoming flow velocity magnitude and direction from measurements of the power required by each of the MUAS rotors. Extensive wind-tunnel testing was completed to determine the power required by the fore and aft rotor-pairs at varying flow velocities and directions. The results show that it is possible to map between rotor power consumption and the oncoming flow vectors, however, a unique and accurate mapping is only possible over a very small region of the measurement space. Thus, it is concluded that the practical use of this sensing method is limited. Examination of power consumption curves also revealed that the conditions under which a Vortex Ring State (VRS) develops for small MUAS. The characteristics of VRS development are similar to those of full-size helicopters, indicating that the VRS is Reynolds number independent. The reduction in power consumption due to the presence of updraft flows of various magnitudes was also quantified, indicating that significant endurance improvements of MUAS are possible and can be achieved when operating windward of large buildings.

Automated ATM System Enabling 4DT-Based Operations

As part of the current initiatives aimed at enhancing safety, efficiency and environmental sustainability of aviation, a significant improvement in the efficiency of aircraft operations is currently pursued. Innovative Communication, Navigation, Surveillance and Air Traffic Management (CNS/ATM) technologies and operational concepts are being developed to achieve the ambitious goals for efficiency and environmental sustainability set by national and international aviation organizations. These technological and operational innovations will be ultimately enabled by the introduction of novel CNS/ATM and Avionics (CNS+A) systems, featuring higher levels of automation. A core feature of such systems consists in the real-time multi-objective optimization of flight trajectories, incorporating all the operational, economic and environmental aspects of the aircraft mission. This article describes the conceptual design of an innovative ground-based Air Traffic Management (ATM) system featuring automated 4-Dimensional Trajectory (4DT) functionalities. The 4DT planning capability is based on the multi-objective optimization of 4DT intents. After summarizing the concept of operations, the top-level system architecture and the key 4DT optimization modules, we discuss the segmentation algorithm to obtain flyable and concisely described 4DT. Simulation case studies in representative scenarios show that the adopted algorithms generate solutions consistently within the timeframe of online tactical rerouting tasks, meeting the set design requirements.

Sensing Unsteady Pressure on MAV Wings: A New Method for Turbulence Alleviation

Experiments at low Reynolds numbers were performed on a pressure tapped NACA 2313 wing in a 3 x 2 x 9 meter wind tunnel under nominally smooth (Ti = 1.2%) and turbulent (Ti = 7.2%) flows at a mean flow velocity of 8ms-1 (Re ≈120,000). The NACA 2313 wing is a replica of Micro Air Vehicle (MAV) wing of the Flash 3D aircraft used at RMIT University for research purposes. Unsteady surface pressures were measured to understand if the information could be adopted for resolving turbulence-induced perturbations and to furthermore use it in a turbulence mitigation system. Two span-wise locations of chord-wise pressure were acquired when tested under the two different flow conditions. It was discovered that at both span-wise locations, a local Coefficient of Pressure (Cp) held high correlation to the chord-wise Cp integration and allowed for a linear relationship to be formed between the two variables. The defined relationship provided a 95% confidence for angles of attack below stall and was used to estimate the integrated chord-wise pressure coefficient at a particular span wise location. The relationship between a single pressure tap and the integrated Cp of that chord-wise section was valid for the two different span-wise locations with similar defining equations. As one pressure tap is sufficient to adequately estimate the integrated Cp on a chord-wise wing section, a limited amount of pressure taps across the wings span approximates the pressure distribution across the span and eventually approximates the flight perturbations. Being a novel method of sensing aircraft disturbance, applications are not restricted to MAV. The methodology presented could very well be applied to larger aircraft to reduce the effects of turbulence within the terminal area and can provide other means of active stabilization.

4-Dimensional trajectory optimisation algorithm for air traffic management systems

This paper presents Multi Objective Trajectory Optimization (MOTO) algorithms that were developed for integration in state-of-the-art Air Traffic Management (ATM) and Air Traffic Flow Management (ATFM) systems. The MOTO algorithms are conceived for the automation-assisted replanning of 4-Dimensional Trajectories (4DT) when unforeseen perturbations arise at strategic and tactical online operational timeframes. The MOTO algorithms take into account updated weather and neighbouring traffic data, as well as the related forecasts from selected sources. Multiple user-defined operational, economic and environmental objectives can be integrated as necessary. Two different MOTO algorithms are developed for future implementation in ATM systems: an en-route variant and a Terminal Manoeuvring Area (TMA) variant. In particular, the automated optimal 4DT replanning algorithm for en-route airspace operations is restricted to constant flight level to avoid violating the current vertical airspace structure. As such, the complexity of the generated trajectories reduces to 2 dimensions plus time (2D+T), which are optimally represented in the present 2D ATM display formats. Departing traffic operations will also significantly benefit from MOTO-4D by enabling steep/continuous climb operations with optimal throttle, reducing perceived noise and gaseous emissions.

Minimizing the Cost of Weather Cells and Persistent Contrail Formation Region Avoidance Using Multi-Objective Trajectory Optimization in Air Traffic Management

Exhaust heat recovery systems are used to make use of otherwise wasted heat from a car engine. The unique system design described herein utilises thermoelectric generators (TEGs) and heat pipes with its key advantage being it is a passive solid state design. The use of these components creates a few design This paper gives the concepts and mathematically models required for the development of the Multi Objective Trajectory Optimization (MOTO) functionalities to be implemented into the next generation of ATM system. MOTO algorithms are introduced whereby data from various sources are utilized to optimize flight paths for various user defined objectives. The algorithms require digital resources of weather, aircraft data, metrological maps and air traffic. These will be used in conjunction with various mathematical models to compute trajectories that minimize various objectives such as fuel, emissions and operational cost. The automated 4D trajectory computation algorithms are restricted to single flight level to not violate the current layered vertical air route structure for the cruise phase of flight. As such the complexity of the generated trajectories reduces to 2 dimensions plus time (2D+T), which are adequately represented in the radar display, and this improves the ATC Operators familiarity in the tactical trajectory management and deconfliction, as control over vertical separation is maintained. This also permits the ATCO to amend the flight level of an optimized trajectory in the traditional manner if necessary. The constant flight level limitation will theoretically produce a sub-optimal flight path however the computed trajectory will remain more efficient than a straight line as the atmospheric winds are exploited to maximize flight speed while reducing fuel burn and emissions.

Modelling and Evaluation of Persistent Contrail Formation Regions for Offline and Online Strategic Flight Trajectory Planning

This chapter presents a contrail mapping algorithm developed for integration into a Multi-objective Trajectory Optimisation (MOTO) software framework, targeting the mitigation of environmental impacts associated with aviation-induced cloudiness. The presented linear contrail mapping algorithm exploits analytical and empirical models to determine the formation, persistence and radiative properties of contrails along a defined flight trajectory . In order to determine the contrail formation and persistence, the algorithm takes into account aircraft characteristics as well as relative humidity, temperature, pressure as well as the speed and shear of winds aloft, derived from suitable weather forecast data inputs. The linear contrail mapping algorithm generates an accurate mapping of the contrail persistence and associated Radiative Forcing (RF) along a flight trajectory based on inputs of weather data and aircraft state. A 3D contrail mapping algorithm is developed by executing the linear contrail mapping algorithm along an arbitrary number of virtual sounding trajectories. These virtual trajectories are constructed radially around a centre position, at individual flight levels. Multiple 3D mappings are exploited to characterise time variations, ultimately leading to a 4-dimensional (4D) mapping in space and time of contrail formation, persistence and RF properties. These 4D contrail mappings can be exploited in a MOTO software framework to assess and minimise the environmental impacts associated with contrails.

Multi-objective 4D Trajectory Optimization for Online Strategic and Tactical Air Traffic Management

Significant evolutions of aircraft, airspace and airport systems design and operations are driven by the continuous increase of air transport demand worldwide and by the concurrent push for a more economically viable and environmentally sustainable aviation. In the operational context, novel avionics and air traffic management (ATM) systems are being developed to take full advantage of the available communication, navigation and surveillance (CNS) performance. In order to attain higher operational, economic and environmental efficiencies, the generation of 4-dimensional trajectories (4DT) shall integrate optimisation algorithms addressing multiple objectives and constraints in real-time. Although extensive research has been performed in the past on the optimisation of aircraft flight trajectories and very efficient algorithms were widely adopted for the optimisation of vertical flight profiles, it is only in the last few years that higher levels of integration were proposed for automated 4DT planning and rerouting functionalities. This chapter presents the algorithms conceived for integration in next generation avionics and ATM Decision Support Systems (DSS), to perform the multi-objective optimisation of 4DT intents. In particular, the algorithms are developed for 4DT planning, negotiation, and validation (4-PNV) in online strategic and tactical operational scenarios, and are conceived to assist the human flight crews and ATM operators in planning and reviewing optimal 4DT intents in high air traffic density contexts. The presented implementation of the multi-objective 4DT optimisation problem includes a number of environmental objectives and operational constraints, also accounting for economic and operational performances as well as weather forecast information from external sources. The current algorithm verification activities address the Arrival Manager (AMAN) scenario within a Terminal Manoeuvring Areas (TMA), featuring automated point-merge sequencing and spacing of multiple arrival traffic in quasi real-time.