Abstract

Aircraft collision avoidance maneuvers are important and complex applications. Curved flight exhibits nontrivial continuous behavior. In combination with the control choices during air traffic maneuvers, this yields hybrid systems with challenging interactions of discrete and continuous dynamics. As a case study illustrating the use of a new proof assistant for a logic for nonlinear hybrid systems, we analyze collision freedom of roundabout maneuvers in air traffic control, where appropriate curved flight, good timing, and compatible maneuvering are crucial for guaranteeing safe spatial separation of aircraft throughout their flight. We show that formal verification of hybrid systems can scale to curved flight maneuvers required in aircraft control applications. We introduce a fully flyable variant of the roundabout collision avoidance maneuver and verify safety properties by compositional verification. Document type: Part of book or chapter of book

Abstract

Neste trabalho foi analisado um novo modelo de operação em rotatória implantado no município de Araraquara-SP, cuja preferência é da via principal que possui semáforos a certa distância da interseção, com o início de verde em diferentes momentos para cada direção da via principal. Os semáforos defasados permitem o ordenamento do fluxo e geram brechas maiores ao reduzir o headway entre veículos, o que possibilita a operação em pelotões e, consequentemente, aumenta a capacidade da interseção e reduz o número de conflitos. A proposta foi comparada com duas outras operações mais usuais: rotatória moderna e rotatória convencional (com e sem preferência para a via circular, respectivamente). A elaboração do trabalho foi dividida em cinco partes: primeiramente é apresentada, de forma detalhada, como é operado o modelo proposto. Em seguida, com dados obtidos em campo por filmagens nas três operações de rotatória em análise, foram determinadas as brechas críticas, através de cinco métodos determinísticos, e o headway em fila pelo método de Siegloch (1973). A terceira parte do trabalho foi a análise das distribuições de veículos na rotatória que, junto com o modelo de aproveitamento das brechas, compuseram os modelos de capacidade. Durante a quarta etapa foi realizada uma adaptação da metodologia de dimensionamento semafórico de Webster devido à possibilidade de entrada da via não preferencial, mesmo com o semáforo aberto na via principal, caso haja brecha suficiente. Finalmente, na quinta etapa, com a calibração do software AIMSUN, foram realizadas simulações dos três cenários utilizando o atraso crítico de controle como variável de análise, ou seja, o maior atraso entre as aproximações devido à existência da interseção. Foi verificado que ao instalar os semáforos na via principal, que possui a preferência na entrada da rotatória, o aumento da capacidade, principalmente ao comparar cenários com alta taxa de conversão ou em situação de fluxo desequilibrado entre as aproximações. Ao final foram calibrados modelos de capacidade para a operação em estudo baseados nas simulações, podendo ser aplicados em qualquer situação ao variar a brecha crítica e o headway em fila. In this work, a new traffic-circle operation, implemented in the city of Araraquara-SP, was analysed. The operation consists in offer the traffic preference to the main road with traffic lights installed before the approximation point, with the green time beginning in different moments in which direction to order the use of the intersection and to generate larger gaps by reducing the headway between vehicles, allowing the operation in platoons. The objective is to increase the capacity of the intersection and to reduce the number of conflicts. The proposal was compared with two other more usual operations: roundabouts and conventional traffic circle (with and without preference for the circular track, respectively). The elaboration of the work was divided in five parts: firstly, it is presented, in detail, how the signalized traffic circle is operated. Then, with data obtained in the field by recording the three operations in analysis, the critical gaps were determined, through five deterministic methods, and the follow-up headway. The third part of the work was the analysis of vehicle distributions at the traffic circles and, together with the gap utilization model, the capacity models were determined. During the fourth stage, Webster\\'s signal methodology was adapted because of the possibility of non-preferential entering in the traffic circle, even with the green light of the signal on the main road, if there is a sufficient gap. Finally, in the fifth step, with the calibration of the AIMSUN software, simulations of the three scenarios were performed using, as a variable, the critical control delay (the highest delay between the approximations due to the existence of the intersection). It was verified that offer the traffic preference to the main road with traffic lights installed before the approximation point, the capacity increases significantly, mainly when comparing scenarios with high conversion rate or in situation of unbalanced traffic flow between the approaches. At the end, capacity models were calibrated for the study operation based on the simulations, and it may be applied in any situation by varying the critical gap and the follow-up headway.

Abstract

The problem of minor vehicles crossing or merging into the major stream at unsignalized priority-controlled intersections is well-known. Numerous solutions involve various assumptions concerning the major headway distributions, number of major lanes, critical gap distributions, etc. Such cases can be divided into two main groups: intersections with two streams (one major and one minor stream) and intersections with more than two streams (more than one major stream and one minor stream). At roundabouts, also at single-lane roundabouts, there are similar problems like the ones at other unsignalized priority-controlled intersections. A vehicle at the roundabout approach can only cross the pedestrian crossing when a sufficient time-gap between two pedestrians (or cyclists) is provided. A vehicle at the roundabout entries can only merge into the major stream when a sufficient gap between the two vehicles in the major stream is provided. Because of that, single-lane round-abouts can also be treated as unsignalized intersections with two major lanes: the first one in its circulatory roadway and the second one on the pedestrian crossing. Problematika križanja ali vključevanja stranskega prometnega toka v nivojskih križiščih, kjer je prometni režim urejen z glavno in stransko prometno smerjo, je znan. Številni pristopi vsebujejo različne predpostavke, ki zadevajo porazdelitev glavnega prometnega toka, število prometnih pasov na glavni prometni smeri, kritično časovno praznino ... Take sisteme lahko razdelimo v dve glavni skupini: križišča z dvema tokoma (enim glavnim in enim stranskim) in križišča z več kot dvema tokoma (več kot dva glavna prometna toka in en stranski prometni tok). V krožnih križiščih, tudi v enopasovnih, obstajajo enaki problemi, kot pri drugih nivojskih križiščih, urejenih s prometnim režimom glavne in stranske prometne smeri. Vozilo na uvozu v krožno križišče se lahko priključi v glavni prometni tok le v primeru, ko je časovni presledek med dvema pešcema (ali kolesarjema) zadosti velika. Vsled tega lahko tudi enopasovna krožna križišča obravnavamo kot nesemaforizirana križišča z dvema glavnima prometnima tokoma: prvim v krožnem vozišču in drugem na prehodu za pešce.