Like manned aircraft, UAVs need the capability to timely detect and avoid other traffic. In case of a fully autonomous detect, sense and avoid system, every falsely identified threat will cause an unnecessary avoidance maneuver. Furthermore, information that is not explicitly available to the avoidance function cannot be taken into account when computing a maneuver. Given a situation where the time to conflict provides sufficient margin, involving the human operator in the detect, sense and avoid cycle can mitigate these issues. With the appropriate level of system authority, it is possible to combine collision avoidance function availability and continuity (e.g. in case of a control link failure) with the benefits that can be obtained from operator involvement. This paper discusses the integration of conflict probing data into a cockpit display of traffic information and into an enhanced/synthetic vision primary flight display. The resulting user interface concept is intended to support the operator in the assessment of the traffic situation, providing an adequate understanding of the impact of maneuvering on the future separation with traffic. Following this, the design of an experiment to explore the impact of the conflict probes on conflict assessment and maneuvering is presented. Results from an initial evaluation show an improvement in the assessment of the traffic situation, resulting in more effective and efficient conflict resolution maneuvers, and less unwarranted maneuvers.
One of the biggest challenges in the development of detect, sense and avoid systems is to achieve both an extremely low missed detection probability and an acceptable false alarm rate. In case of a fully autonomous system, every falsely identified threat will cause an unnecessary avoidance maneuver. In this paper, a concept is described that combines the requirement of collision avoidance function availability and continuity (e.g. in case of a control link failure) with the benefits from operator involvement in the detect, sense and avoid cycle for those situations where the time to conflict provides a sufficient margin. When involving the human operator, it must be ensured that the positive effects of a warranted contribution outweigh the negative effects of an unwarranted one. A second challenge when involving the operator is to find the right balance between system-and operator authority. This paper starts with an identification and analysis of opportunities and constraints. The requirement of function availability in case of a control link failure is translated into a range of possible authority levels for the detect, sense and avoid functions. Based on the results, a concept for operator involvement is proposed and it is illustrated how the level of system authority affects the role of the operator. From an analysis of earlier work in the area of conflict prediction, assessment and resolution, conflict probing is identified as a means to support the operator in determining, selecting and/or assessing maneuvers. To explore the potential of the probing concept, a multi-dimensional conflict probe has been integrated into a cockpit display of traffic information and a head-up display. Results from an initial evaluation show an improvement in the assessment of the traffic situation, resulting in more effective and efficient conflict resolution maneuvers and less unwarranted maneuvers.
To maintain separation with other traffic, terrain, threats and special use airspace independent of control link availability, UAVs require the capability of autonomous conflict detection and resolution. In previous research it has been illustrated how conflict probing provides the basis for a framework to integrate the results from multiple conflict prediction functions and how conflict probing can be used to find two-dimensional resolution maneuvers.Conflict resolution should be able to use the full performance capabilities of the UAV, rather than command standard resolution maneuvers designed to accommodate the worst performing class of UAVs. The available 3D space for conflict resolution can be maximized by combining vertical and lateral maneuvers. This requires integrated control authority allocation and envelope protection functionality, taking into account the effect of lateral maneuvering on the vertical performance and load factor margin. The maximum safe maneuvering space should also utilize the ability to convert the available speed margin relative to V min or V max (excess kinetic energy) into altitude (potential energy). For humans it is almost impossible to maximize the maneuvering performance in this way without violating one or more maneuvering constraints such as angle of attack, stall speed, load factor and bank angle.The goal of the current research is to develop an autonomous conflict resolution system which uses (well) balanced lateral and vertical maneuver authorities, and if needed, can safely utilize the most aggressive possible vehicle maneuver capability. This paper discusses an approach to provide integrated vertical and lateral airplane maneuver authority allocation and envelope protection functions. These functions have been implemented in the Total Energy Control System / Total Heading Control System (TECS/THCS) design to generate example time responses of single and combined vertical and lateral maneuvers, including energy exchange ("zoom") maneuvers. The methodology also provides for 3D end-state prediction and display on an enhanced SVS PFD. It is also illustrated how information about the maximum safe maneuvering authority is integrated into the conflict prevention/resolution function.
Recent guidance from the U.S. Federal Aviation Administration suggests that self separation needs to be a component of an Unmanned Aircraft System Sense and Avoid solution. The greater time horizon associated with self separation allows for pilot-in-the-loop operation, and, in fact, the nature of self separation demands more pilot involvement. The ability to effectively conduct pilot-in-the-loop self separation will be critically dependent on decision aides and advanced displays that allow pilots to make accurate and timely maneuvering decisions. This paper starts with a presentation of eight criteria that should be considered when defining requirements for a future separation assurance and collision avoidance system. Using these criteria, it is illustrated how the concept of conflict probing and the associated scalability enables a range of possible implementations, specifically matched to the available data, interfaces and displays.
This paper addresses the design and implementation of a conceptual Enhanced/Synthetic Vision Primary Flight Display format. The goal of this work is to explore the means to provide the operator of a UAV with an integrated view of the constraints for the velocity vector, resulting in an explicit depiction of the margins/boundaries of the multi-dimensional maneuver space. For non-time-critical situations, this is expected to provide support when the operator has the authority to manually set avoidance maneuvers, or approve, veto or modify velocity vector changes proposed by the automation. The integration of the upper bounds of the maneuver space, resulting from energy constraints, and the lower bounds, resulting from terrain will be illustrated. Additionally, the application of a maneuver cost function will be discussed, for identifying and prioritizing conflict avoidance options from an integrated multi-dimensional maneuver space, and communicating those to the operator. Although the integrated avoidance functions have been developed with the UAV application in mind, they have equal merit for manned aircraft. The need for specific GUI elements depends on the level of authority of the system and the role of the operator/pilot, which may differ between manned and unmanned applications.
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