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(searched for: doi:10.2514/1.G000691)
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Zhaoxuan Liu, Jun Zhang, Yanbo Zhu,
Journal of Guidance, Control, and Dynamics, Volume 45, pp 1017-1032; https://doi.org/10.2514/1.g006206

Abstract:
A waypoint-based trajectory planning framework is proposed. The motivation is to allocate capacity-constrained airspace resources for pretactical safe separation in the manned and unmanned aircraft integrated airspace. First, the spatial-temporal related aircraft with high conflict risks are clustered to reduce the scale of the problem induced by increasing traffic volumes. A two-stage optimization is further implemented. In the first stage, trajectories within each group are sequentially planned in order determined by a priority ranking mechanism, where the relative conflict-critical aircraft takes more deconflicting responsibilities. A distributed decision-making architecture is developed to account for aircraft heterogeneity in the sequential deconflicting process. In the second stage, the high-quality solutions of different groups are coupled together to obtain the overall trajectory distribution under system-wide resource capacity constraints. Empirical studies using operational data in China show that the proposed method reduces 95% of conflicts with low cost and few aircraft disturbance, which demonstrate superiority in deconflicting effectiveness and efficiency. In addition, the distributed decision-making process ensures scalability and flexibility by allowing aircraft to determine the optimal trajectories based on their internal tradeoffs. Several major conclusions and future work are presented based on the current investigation.
, Zhi Jun Lim, Sameer Alam, Narendra Pratap Singh
Journal of Guidance, Control, and Dynamics, Volume 44, pp 2263-2275; https://doi.org/10.2514/1.g005802

Abstract:
Approach and landing accidents have resulted in a significant number of hull losses worldwide. Technologies (e.g., instrument landing system) and procedures (e.g., stabilized approach criteria) have been developed to reduce the risks. This paper proposes a data-driven method to learn and interpret flight’s approach and landing parameters to facilitate comprehensible and actionable insights into flight dynamics. Specifically, two variants of tunnel Gaussian process (TGP) models are developed to elucidate aircraft’s approach and landing dynamics using advanced surface movement guidance and control system (A-SMGCS) data, which then indicates the stability of flight. TGP hybridizes the strengths of sparse variational Gaussian process and polar Gaussian process to learn from a large amount of data in cylindrical coordinates. This paper examines TGP qualitatively and quantitatively by synthesizing three complex trajectory datasets and compared TGP against existing methods on trajectory learning. Empirically, TGP demonstrates superior modeling performance. When applied to operational A-SMGCS data, TGP provides the generative probabilistic description of landing dynamics and interpretable tunnel views of approach and landing parameters. These probabilistic tunnel models can facilitate the analysis of procedure adherence and augment existing aircrew and air traffic controller’ displays during the approach and landing procedures, enabling necessary corrective actions.
Published: 10 February 2021
by MDPI
Applied Sciences, Volume 11; https://doi.org/10.3390/app11041600

Abstract:
Air transport is considered to be the safest mode of mass transportation. Air traffic management (ATM) systems constitute one of the fundamental pillars that contribute to these high levels of safety. In this paper we wish to answer two questions: (i) What is the underlying safety level of ATM systems in Europe? and (ii) What is the dispersion, that is, how far does each ATM service provider deviate from this underlying safety level? To do this, we develop four hierarchical Bayesian inference models that allow us to infer and predict the common rate of occurrence of SMIs, as well as the specific rates of occurrence for each air navigation service provider (ANSP). This study shows the usefulness of hierarchical structures when it comes to obtaining parameters that enable risk to be quantified effectively. The models developed have been found to be useful in explaining and predicting the safety performance of 29 European ATM systems with common regulations and work procedures, but with different circumstances and numbers of aircraft, each managing traffic of differing complexity.
Published: 25 November 2020
Robotics and Autonomous Systems, Volume 136; https://doi.org/10.1016/j.robot.2020.103705

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Haotian Niu, Cunbao Ma, Pei Han
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Volume 235, pp 621-645; https://doi.org/10.1177/0954410020953045

Abstract:
With the increasing density level of airspace, the flawed logic of resolution in air conflict has become a potential hazard to keep flight safety for civil aviation. A powerful decision-support system is needed to identify and resolve potential conflicts on planned trajectory in advance. Existing studies on this subject mainly focus on the centralized means, but seldom consider the decentralized approaches. In this paper, a decentralized method is proposed so that each aircraft can generate the collision-free Reference Business Trajectory (RBT) autonomously, and resolve potential conflicts while conforming to the unified rules. Firstly, a Synchronous Discrete-Time-Discrete-Space trajectory modeling is developed to divide the continuous planned trajectory into multiple trajectory segments according to motion state. Thus, the collision can be accurately located at one certain risky segment, and the corresponding collision time can be acquired precisely. Through a weight analysis of collision time, the critical trajectory segment is determined to implement the task of conflict resolution. Then, the Optimal Reciprocal Collision Avoidance (ORCA) algorithm is adopted and extended to determine the collision-free maneuver with the consideration of direction selectivity. At last, the Trajectory Change Points (TCPs) are achieved by the quadratic program for each aircraft. The proposed method can help aircraft generate collision-free RBT in decentralized way successfully. Several simulations are conducted to confirm the validity and efficiency of the proposed approach.
Yuheng Guo, Xiang Li, HouJun Zhang, Ming Cai, Feng He
Journal of Guidance, Control, and Dynamics, Volume 43, pp 955-966; https://doi.org/10.2514/1.g004669

Abstract:
A data-driven impact-time-control guidance (DD-ITCG) method based on proportional navigation guidance (PNG) is presented in this study, in which the assumption of constant velocity adopted in previous reports is not necessary, and it is applicable to cases with significant velocity changes. The motivation of the presented DD-ITCG is that, for a given flight state vector (FSV, including position and velocity) and a given target position, the PNG trajectory from this FSV to this target as well as the corresponding PNG time-to-go (TGO) are determined. Based on this fact, a database including input FSV and output of PNG TGO is built. At a time instant in DD-ITCG, there are two TGO quantities, one is PNG TGO of PNG trajectory, and the other one is the required TGO. Hence there is a TGO error between PNG TGO and required TGO. Then a TGO error rate with opposite sign of TGO error is set to decrease the TGO error to zero. The relation between the TGO error rate and the DD-ITCG commands is analyzed, based on which the DD-ITCG commands are computed by virtue of the database. Case studies of a hypersonic flight vehicle impact time control show the performances of the presented DD-ITCG method, and some observations in these case studies are discussed.
Published: 18 March 2020
Abstract:
Remotely Piloted Aircraft Systems (RPAS) are new airspace users that require to be safely integrated into the non-segregated airspace. Currently, their integration is planned for the horizon 2025, but there is a lot of pressure by RPAS operators to fly as soon as possible. This research focuses on the development of a risk-based framework for the integration of RPAS in non-segregated airspace. The risk-based framework relies on a hierarchical methodology that is split into two time horizons: design and operation. Different operational and geometrical factors characterise each stage. Then, a set of risk and operational indicators are defined for each stage. These indicators evaluate the operational airspace state and provide information about how the integration of RPAS should be. Primary results provide information about geographical and temporary restrictions. Geographical restrictions refer to the airways that favour or inhibit the integration of RPAS, and temporary restrictions denote the time span when the RPAS can pierce into the airspace.
Javier A. Pérez–Castán, Fernando Gómez Comendador, Alvaro Rodriguez–Sanz, Rosa M. Arnaldo, Jaime Torrecilla
Published: 17 December 2019
MATEC Web of Conferences, Volume 304; https://doi.org/10.1051/matecconf/201930405003

Abstract:
The forthcoming integration of Remotely Piloted Aircraft System (RPAS) is one of the cmost omplex challenges for aviation. Europe draws to allow operating RPAS and conventional aircraft in non-segregated airspace by 2025, but this demanding perspective entails a thorough analysis of the different aspects involved. The RPAS integration in non-segregated airspace cannot imply an increase in the safety levels. This paper assesses how the RPAS integration affects safety levels. The goal is to regulate the number of RPAS that can jointly operate with conventional aircraft regarding conflict risk. This approach benchmarks a Calculated Level of Safety (CLS) with a Target Level of Safety (TLS). Monte Carlo (MC) simulations quantify the TLS based on schedules of conventional aircraft. Then, different combinations of conventional aircraft and RPAS provide different CLS. MC simulations are performed based on probabilistic distributions of aircraft performances, entry times and geographical distribution of aircraft. The safety levels are based on a conflict-risk model because the primary metrics are average number of conflicts and average conflict duration. The methodology is applied to one flight level of en-route airspace. The results provide restrictions to the number of RPAS that can jointly operate with conventional aircraft. Particularly, the TLS is quantified for four conventional aircraft and MC simulations provide the combinations of conventional aircraft and RPAS that fulfil the CLS. The same number of RPAS than conventional aircraft shows an increase over 90% average number of conflicts and 300% average conflict time.
, Krista Rand,
Published: 22 March 2019
Aerospace Science and Technology, Volume 88, pp 350-361; https://doi.org/10.1016/j.ast.2019.03.035

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, , A. Rodríguez-Sanz, , R. Arnaldo Valdés, L. Pérez Sanz
Transportation Research Part C: Emerging Technologies, Volume 96, pp 231-250; https://doi.org/10.1016/j.trc.2018.09.008

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