Archives Ouvertes HAL
Toutes les publications de l'ENAC en direct.
All ENAC publications.
[hal-04659593] Climate and energy impact analysis of electric, hybrid-electric and hydrogen aircraft in prospective scenarios for air transport
To meet climate impact reduction objectives, the aviation sector must both accelerate the improvement of the fleet efficiency and the deployment of low-carbon energy carriers. This implies to develop new concepts of aircraft with a reduced climate impact than previous ones and possibly more energy efficient. One research direction is the investigation of electric, hybrid-electric and hydrogen aircraft concepts to possibly reduce emissions. Indeed, these concepts imply the direct usage of electricity or hydrogen from electrolysis which may be potential low-carbon energy carriers. Evaluating the climate impact benefits and energy implications of the deployment of such...
[hal-04201801] Enhancing Travel Resilience: Integrating Alternative Path-Based Robustness Metric in Route Optimization
Unforeseen disruptions, including accidents, adverse weather conditions, and temporary construction, frequently hinder traffic flow in road transportation, forcing passengers to alter their routes. These incidents impart stress and delays on travelers. This article delves into the optimization of itineraries to minimize the impact of disruptions on passengers' journeys, with a focus on the criteria to be considered. We present a new metric for topological robustness that focuses on alternative paths and can be integrated into passengers' decision-making processes for choosing a route. Our simulations, based on static traffic assignment and varying levels of robustness...
[hal-04659651] Controllability assessment and fault-tolerant sizing of UAVs under effector failures
This article presents a methodology for analyzing the controllability and fault-tolerant sizing of fixed-wing and hybrid fixed-wing vertical landing and takeoff (FW-VTOL) unmanned aerial vehicles (UAVs). Building upon previous research focused on multirotor UAVs, the study introduces a new control authority index, redefined dynamics models, and enhanced control allocation techniques to address rotor failures and lock-in-place failures of control surfaces. The methodology considers effector limitations and the unidirectional drag condition for control surface deflection angles. These advancements are combined to assess the linear controllability and accomplish fault...
[hal-04659183] Multi-Agent Reinforcement Learning based Drone Guidance for N-View Triangulation
This article presents a novel approach for controlling a fleet of drones that can track the location of a flying target using onboard omnidirectional cameras. The drones use Multi-Agent Reinforcement Learning (MARL) to learn decentralized policies that optimize their formation and motion around the target, minimizing the uncertainty in the triangulated position. We design a reward function that encourages the trackers to minimize the trace of the covariance matrix of the triangulated position, which is derived from an analytical model of uncertainty propagation. We use Multi-Agent PPO (MAPPO), an extension of Proximal Policy Optimization (PPO) to the multi-agent setting...
[hal-03673359] VETA: Visual eye-tracking analytics for the exploration of gaze patterns and behaviours
Eye tracking is growing in popularity for multiple application areas, yet analysing and exploring the large volume of complex data remains difficult for most users. We present a comprehensive eye tracking visual analytics system to enable the exploration and presentation of eye-tracking data across time and space in an efficient manner. The application allows the user to gain an overview of general patterns and perform deep visual analysis of local gaze exploration. The ability to link directly to the video of the underlying scene allows the visualisation insights to be verified on the fly. The system was motivated by the need to analyse eye-tracking data collected from...
[hal-04655042] Efficient influence functions for Sobol' indices under two designs of experiments
In this note, we are interested in the asymptotic efficiency of Sobol’ indices esti- mators. After recalling the basis of asymptotic efficiency, we compute the efficient influence functions for Sobol’ indices in two different contexts: the Pick-Freeze and the given-data settings.
[hal-04653350] Assessment of Number of Critical Satellites for Ground-Based Augmentation System Continuity Allocation to Support Category II/III Precision Approaches
The ground-based augmentation system (GBAS) is a regional system supporting navigation and ensuring the integrity of aircraft near airports during precision approaches. Standardized at the international level, GBAS Approach Service Types (GASTs) C and D, which are defined for the GPS L1 signal, support CAT I and II/III precision approaches with decision heights of 200 and 50 ft, respectively. However, the future GBAS, GAST E, which utilizes dual-frequency and multi-constellation signals, and the GAST D1, defined for both GPS L1 and Galileo E1 signals, require the establishment of standards. To define the continuity requirement, the number of critical satellites must be...