A conflict resolution algorithm considering design objective optimization in collaborative design

A method for conflict detection and resolution based on the parameterization of the aircraft intents is presented. The method is also based on the use of predefined trajectory patterns, which are in fact flight intents; these patterns include standard airline procedures and air traffic control regulations. The conflict resolution problem is formulated as a parametric optimization problem subject to constraints; the optimality criterium is defined so that the deviation from the intended (preferred) trajectories in the lateral profile is minimized. The resolution trajectory patterns take into account changes of the nominal waypoints (vectoring) and changes of the aircraft speeds. The method is applied to the case of multiple conflicts among commercial transport aircraft in converging traffic in the terminal area; different scenarios are considered, which include locked aircraft, that is, aircraft whose trajectories are known and fixed. The conflict detection and resolution algorithm relies on a kinetic trajectory predictor (nonlinear point-mass model with variable mass), which is accurate, flexible, and transparent, and provides the high-fidelity prediction required in the analysis of the demanding terminal area traffic. The cost of the global conflict resolution process is assessed, in terms of extra distance traveled, extra flight time, and extra fuel consumed for each aircraft.

NASA researchers, working under the Aviation System Capacity Program and in conjunction with the FAA Free Flight Program Office, have developed a set of decision support tools to assist terminal area air traffic controllers with control of arrival and departure traffic. Two of these tools, the Final Approach Spacing Tool (FAST) and the Expedite Departure Path (EDP) tool, provide air traffic controllers with heading, speed and altitude advisories to assist in spacing aircraft. This paper describes the conflict prediction and resolution algorithm shared by aFAST and EDP to produce conflict-free aircraft trajectories with realistic conflict resolution maneuvers. The process is accomplished in three stages: prediction, classification and resolution. A conflict prediction scheme is documented which incorporates all applicable FAA separation requirements, including automatic detection of separation during transition from staggered to simultaneous parallel approach operations. A method of classifying predicted conflicts with a limited set of criteria is detailed. Finally, a knowledge-based conflict resolution process is presented which allows for resolution of predicted conflicts in a manner consistent with controller practice: including prioritization of resolution tactics and mixture of multiple degrees of freedom to achieve separation. The scheme has been employed in both closed-loop simulations to determine solution stability and controller-in-the-loop simulations to begin development of the resolution tactics knowledge base.

Under the concept of Free Flight, future air traffic operations may permit the transfer of responsibility for various tasks, including conflict detection and resolution, from ground-based air traffic controllers to the flight crew. While aircraft-based conflict resolution is attractive from a user-preferences standpoint, the degree to which it can efficiently resolve complex conflicts among several interacting aircraft remains a significant issue. The objective of this study is to compare the performance of a decentralized conflict resolution strategy against that of a benchmark centralized conflict resolution strategy. A generalized methodology for such a comparison does not exist; therefore two qualitatively different conflict scenarios, characterized by complex interactions among multiple aircraft, were constructed to conduct simulation studies using an idealized model. Preliminary investigations indicate that a decentralized resolution strategy can successfully solve complex multiple-aircraft problems in real time, albeit with some performance degradation relative to a centralized strategy. Research Scientist, Automation Concepts Research Branch; Mail Stop 210-10; E-mail; kbilimoria@mail.arc.nasa.gov. Associate Fellow, AIAA. f Software Specialist, Raytheon ITSS. Research Assistant, Dept. of Aeronautics and Astronautics. Associate Professor, Dept. of Aeronautics and Astronautics; E-mail: feron@mit.edu. Senior Member, AIAA. Copyright © 2000 by the American Institute of Aeronautics and Astronautics, Inc. No copyright is asserted in the United States under Title 17, U.S. Code. The U.S. Government has a royalty-free license to exercise all rights under the copyright claimed herein for Governmental purposes. All other rights are reserved by the copyright owner. Introduction The advent of new technologies for Air Traffic Management (ATM) has the potential to change the operational paradigm of the air transportation system by delegating more responsibility to the flight deck for airplane trajectory management functions; this includes conflict detection and resolution (CDR this is an idealized representation of a situation where several free aircraft are simultaneously attempting to arrive at some terminal area entry point. The second scenario features two closelyspaced traffic streams (each consisting of several aircraft) intersecting at a common point; this is an idealized representation of aircraft flying along intersecting free routes in en route airspace. The performance of a reactive decentralized resolution method that provides sequential, pairwise conflict resolutions based on a geometric optimization approach10 is compared against that of a proactive centralized resolution method that provides a single coordinated conflict resolution based on a global optimization algorithm.5 Although determining a fully coordinated optimal solution to conflicts involving multiple aircraft is computationally challenging, the centralized conflict resolution method described in Ref. 5 is able to compute these solutions, which are used as benchmarks for the best performance that can be achieved. The performance of decentralized strategies is then compared against these benchmark solutions. This paper is organized as follows: First, the mathematical models used for aircraft trajectories and conflict avoidance are presented. The centralized and decentralized conflict resolution methods used in this study are then outlined. Next, performance measures for conflict resolution are defined, and two conflict scenarios are described. Finally, a comparison of the performance of the decentralized conflict resolution strategy relative to the centralized conflict resolution strategy is presented, along with some general observations about their characteristics.

Stochastic optimal control for aircraft conflict resolution under wind uncertainty

The pilot- and controller-in-the-loop simulation described in this paper demonstrates the potential benefits of a near-term trajectory-based operations concept with datalink communications. Near-term operations with datalink are characterized by a fleet of which not all aircraft are equipped with datalink communications (i.e., mixed equipage). The objectives of this simulation were to continue to develop capabilities such as the conflict resolution algorithm, as well as evaluate new capabilities and concepts such as tactical conflict detection and trajectory-based weather avoidance with feedback from experienced pilots and controllers. Conflict resolutions and tactical conflict detections were compared to controller actions. The direction of the conflict resolution maneuver advised by the algorithm agreed with controller actions 79% of the time when both chose to apply the same type of resolution maneuver to the same aircraft. Comparing controller actions to conflicts detected by the tactical conflict detection function revealed no missed alerts and a false alert rate of 11%. Trajectory-based weather avoidance functions received high ratings from the controllers for usefulness and ease of use. In particular, controllers noted weather avoidance reroutes originating from a simulated traffic management coordinator position alleviated their concerns about potentially disrupting traffic flow management plans, thus expediting the issuance of the reroutes.

An airborne conflict resolution approach is presented that is capable of providing flight plans forecast to be conflict-free with both area and traffic hazards. This approach is capable of meeting constraints on the flight plan such as required times of arrival (RTA) at a fix. The conflict resolution algorithm is based upon a genetic algorithm, and can thus seek conflict-free flight plans meeting broader flight planning objectives such as minimum time, fuel or total cost. The method has been applied to conflicts occurring 6 to 25 minutes in the future in climb, cruise and descent phases of flight. The conflict resolution approach separates the detection, trajectory generation and flight rules function from the resolution algorithm. The method is capable of supporting pilot-constructed resolutions, cooperative and non-cooperative maneuvers, and also providing conflict resolution on trajectories forecast by an onboard FMC.

Conflict is a natural and very typical phenomenon in every field of human world. It has very significant common characteristics and dynamics, and, therefore, it makes sense to examine them together and comparatively. People get involved in conflicts because their interests or their values are challenged. Because the solving of distributed problem, considering how the work of solving a particular problem, can be divided among a number of agents, the domain in which this strategy applies is one in which a macro-level or global perspective of problems and solutions may be best achieved by centralized control. In this paper, it concentrates on the linear programming model to develop its conflict resolution algorithm and implement it on AGENT-0.KeywordsMulti-agentLinear optimizationAgent conflict

In previous work we provided a conflict resolution algorithm allowing agents in stochastic domains (represented by Markov Decision Processes) to maximally satisfy a set of moral or social norms, where such norms are represented by statements in linear temporal logic (LTL). This required the agent designer to provide weights specifying the relative importance of each norm. In this paper, we propose an inverse norm conflict resolution'' algorithm for learning these weights from demonstration. This approach minimizes a cost function based on the relative entropy between a policy encoding the observed behavior and a policy representing optimal norm-following behavior. We demonstrate the effectiveness of the algorithm in a simple GridWorld domain.

Double patterning lithography (DPL) is seen as one of the most promising solutions for new technology nodes such as 32nm and 22nm. However, DPL faces the challenges of handling layout decomposition and overlay errors. Currently, most DPL solutions use post-layout decomposition which requires multiple iterations and designer intervention to achieve a decomposable layout as designs scale larger. Recent research is starting to consider DPL constraints during the layout design phase especially during the detailed routing phase. In this work, we propose DPL-aware grid-based detailed routing algorithm supported with online conflict resolution. The conflict resolution algorithm uses a graph structure to represent geometrical relations between routed polygons and helps in conflict detection and color assignment. Experimental results indicate that this enhanced algorithm reduces the number of conflicts by 60% on average.

In developing the Flight Director and Surveillance System (FDS) [1] for helicopters, a Helicopter Collision Avoidance System (H-CAS) is proposed a software support to assist helicopter pilots to avoid approach or collision in flight. An automatic traffic advisory and conflict resolution algorithm is formulated following its intrude detection. This paper presents the concept of collision avoidance for helicopters in low altitude. The algorithm considers the point mass nonlinear dynamics of helicopter as a three-point interior boundary problem, and solves this optimal control problem using Bang-Bang switching technique. As for H-CAS, the conflict resolution is generated to separate different priority helicopters. Theoretical analysis for the H-CAS is formulated, and simulations on conflicts and resolutions are demonstrated with feasible results.

- Efficient examination scheduling is critical for maintaining academic integrity and optimizing resources in educational institutions. This research focuses on developing an automated exam timetable generation system that dynamically resolves conflicts and accommodates diverse institutional constraints. By leveraging detailed algorithms for faculty invigilation, student schedules, room allocation, and conflict resolution, the system minimizes manual errors and improves operational efficiency. The proposed methodology includes real-time data collection, scheduling optimization, and robust invigilation assignment processes. Expected outcomes of this research include significant reductions in scheduling time, enhanced stakeholder satisfaction, and scalability to accommodate institutional growth. By addressing existing gaps in scheduling methods, this study offers a transformative approach to academic resource management, setting the foundation for advancements in educational technology. Key Words: Examination Scheduling, Timetable Generation, Conflict Resolution, Faculty Availability, Resource Optimization, Educational Technology, Automation, Scalability, Greedy approach, Sophisticated Algorithm

China has been gradually relaxing its ban on the use of low-altitude airspace across the country. To guarantee the high reliability of air traffic management (ATM), conflict detection and conflict resolution (CDR) approaches are indispensable to maintain safe separation between neighbouring small fixed-wing aircraft. In this study, we analyse a temporal and spatial integrated strategy for safety assessment purposes in opening the low-altitude urban airspace of Chinese pilot cities. First, we present a detailed mathematical description of the proposed algorithms based on a spatial grid partitioning system (SGPS). For our system, a conflict detection (CD) algorithm is designed to determine if two trajectories pass through the same grid space within overlapping time windows. A conflict resolution (CR) algorithm integrates a proposed time scheduling-based technique (TST) and vertical change-based technique (VCT), which operate under predetermined basic principles. Then, based on our novel CDR algorithms, a causal model is constructed in graphical modelling and analysis software (GMAS) to generate a state space that can provide a global perspective on scenario dynamics and better understanding of induced conflict occurrences. Finally, simulation results demonstrate that the proposed approach is practical and efficient.

Constrained resource sharing and conflict resolution in Hebe

Introduction: M. A. Mohamed Salih 1 Towards Security, Stability and Sustainability Oriented Strategies of Development in Eastern Africa J.B. Opschoor 2 Sustainable Development and Resource Conflicts in Botswana M.B.K. Darkoh and J.E. Mbaiwa 3 Participation and Governance in the Development of Borana, Southern Ethiopia Johan Helland 4 Conflict Management, Resolution and Institutions Among the Karrayu and their Neighbours Ayelew Gebre 6 Ranchers and Pastoralists: Restructuring of Government Ranching, Uganda Frank Emmanuel Muhereza 8 Resource Competition and Conflict: Herder-Farmer or Pastoralism-Agriculture? Mustafa Babiker 9 Resource Conflicts among the Afar of Northeast Ethiopia Getachew Kassa 10 Livelihood and Resource Competition, Sudan Abdel Ghaffar Mohamed Ahmed 11 Pastoral Commercialisation: On Caloric Terms of Trade and Related Issues Ton Dietz, Abdirizak A. Nunow, Adano W. Roba and Fred Zaal 12 Immediate Problems: A View From A Distance P.T.W. Baxter 13 Changing Gender Roles and Pastoral Adaptation In Omdurman, Sudan Samia El Hadi El Nagar 14 Research-Led Policy Deliberation in Eritrea and Somalia: Searching to Overcome Institutional Gaps Martin Doornbos Notes on Contributors Index

The process of collaborative engineering design is relatively complex, and often results in various conflicts due to multi-actors interactions. Therefore, a critical element of collaborative design would be conflict situations resolution. In this paper, a process traceability based methodology is proposed to support conflict management. This methodology deals mainly with the conflict resolution team identification and the solution impact evaluation issues. A process metamodel is proposed in order to allow the design process traceability and the data dependencies network identification; which makes it possible to identify the conflict resolution actors as well as to evaluate the selected solution impact