Causal simulation models for facing third millennium air transport sustainability

Transportation Research Part C: Emerging Technologies

Guasch

2016

Abstract:The Traffic Alert and Collision Avoidance System (TCAS) is a world-wide accepted lastresort means of reducing the probability and frequency of mid-air collisions between aircraft. Unfortunately, it is widely known that in congested airspace, the use of the TCAS may actually lead to induced collisions. Therefore, further research regarding TCAS logic is required. In this paper, an encounter model is formalised to identify all of the potential collision scenarios that can be induced by a resolution advisory that was generated previously by the TCAS without considering the downstream consequences in the surrounding traffic. The existing encounter models focus on checking and validating the potential collisions between trajectories of a specific scenario. In contrast, the innovative approach described in this paper concentrates on quantitative analysis of the different induced collision scenarios that could be reached for a given initial trajectory and a rough specification of the surrounding traffic. This approach provides valuable information at the operational level. Furthermore, the proposed encounter model can be used as a test-bed to evaluate future TCAS logic changes to mitigate potential induced collisions in hot spot volumes. In addition, the encounter model is described by means of the coloured Petri net (CPN) formalism. The resulting state space provides a deep understanding of the cause-and-effect relationship that each TCAS action proposed to avoid an actual collision with a potential new collision in the surrounding traffic. Quantitative simulation results are conducted to validate the proposed encounter model, and the resulting collision scenarios are summarised as valuable information for future air traffic management (ATM) systems.

Section: Cpn Formalismmentioning

confidence: 99%

Coloured Petri net-based traffic collision avoidance system encounter model for the analysis of potential induced collisions

Tang

Transportation Research Part C: Emerging Technologies

Guasch

2016

“…One of the most powerful quantitative analysis tools of PN and CPN is the coverability tree (Piera et al, 2004), which has been widely used in several fields, such as system manufacturing, air transport logistics, etc (Mujica et al, 2010, Piera et al, 2014. The goal of the coverability tree is to find all of the markings that can be reached from a certain initial system state, representing a new system state at each tree node and representing a transition activated in each arc.…”

Section: Abm State Space Analysismentioning

confidence: 99%

State space analysis for model plausibility validation in multi-agent system simulation of urban policies

Buil

Ginters

2016

Journal of Simulation

Multi-agent system (MAS) models have been increasingly applied to the simulation of complex phenomena in different areas, providing successful and credible results. However, model validation is still an open problem. The complexity of the stochastic interaction between agents, together with a large number of parameters, can make validation procedures intractable. Particular validation difficulties appear in social science using MAS models when agents are defined as spatial objects to computationally represent the behaviour of individuals to study emergent patterns arising from micro-level interactions. This paper considers some of the difficulties in establishing the verification and validation of agent-based models (ABMs) and proposes the use of coloured Petri net (CPN) formalism to specify agent behaviour to check whether the model looks and behaves logically. Model plausibility is used to express the conformity of the model with a priori knowledge about the process. A proof-of-concept is presented by means of a case study to test the robustness of emergent patterns through sensitivity analyses and can be used for model calibration. The proposed methodology has been applied in the European Future Policy Modelling project (www.fupol.eu) to create trust and increase the credibility of the ABMs developed to foster e-participation in the design of urban policies by means of simulation techniques.

“…17,25,26 In essence, the problem becomes to a search problem in which the ATM can clearly determine the traffic maneuvers that could lead to a TCAS failure in CA.…”

Section: Colored Petri Net Formalismmentioning

confidence: 99%

“…For a flight scenario, the CPN model has proven to be very useful for checking a variety of state space situations, opening the whole tree, understanding the cause-effect relationship of each action and how the effects of an action are propagated upstream and downstream through the different actions. 17,25,26 In essence, the problem becomes to a search problem in which the ATM can clearly determine the traffic maneuvers that could lead to a TCAS failure in CA.…”

Section: E Denotes the Arc Expression E(a I ) Such As Ementioning

confidence: 99%

A causal model to explore the ACAS induced collisions

Tang

Proceedings of the Institution of Mechanical Engineers, Part G:

Ruiz

2014

Current Air Traffic Management research programs (i.e. Single European Sky ATM (air traffic management) Research (SESAR), next generation air transportation system (NextGen)), try to overcome airside capacity shortages while improving cost-efficient operations and safety. An increment in the airspace traffic density can lead to congested traffic scenarios for which it becomes necessary to develop new safety procedures that address multithread threats. This paper considers some of the difficulties in establishing validation of the airborne collision avoidance system (ACAS), which constitutes the last-resort for reducing the risk of near mid-air collision between aircraft in a multithread scenario. A causal model that is specified in Colored Petri Net (CPN) formalism is presented as a key approach to analyze the state space of a congested traffic scenario in which the events that could transform a conflict into a collision are identified, providing a challenging tool not only for validation but also for the implementation of a new ACAS logic. The InCAS EuroControl simulator has been used to illustrate the importance of cause-effect analysis for the relationships between various encounters that arise in a multithread scenario, in which TCAS II v. 7.1 fails to avoid a collision when two Resolution Advisories are issued without consideration of the downstream effects.