C. Borst

An Ecological Approach to the Supervisory Control of UAV Swarms

Advances in miniaturized computer technology have made it possible for a single Unmanned Aerial Vehicle (UAV) to complete its mission autonomously. This also sparked interest in having swarms of UAVs that are cooperating as a team on a single mission. The level of automation involved in the control of UAV swarms will also change the role of the human operator. That is, instead of manually controlling the movements of the individual UAVs, the system operator will need to perform higher-level mission management tasks. However, most ground control stations are still tailored to the control of single UAVs by portraying raw flight status data on cockpit like instruments. In this paper, the ecological interface design paradigm is used to enhance the human-machine interface of a ground control station to support mission management for UAV swarms. As a case study, a generic ground-surveillance mission with four UAVs is envisioned. A preliminary evaluation study with 10 participants showed that the enhanced interface successfully enables operators to control a swarm of four UAVs and to resolve failures during mission execution. The results of the evaluation study showed that the interface enhancements promoted creative problem-solving activities to scenarios that could not have been solved by following a fixed procedure. However, the results also showed that the current interface still required control actions to be performed per single UAV, making it labor intensive to change mission parameters for swarms consisting of more than four UAVs.

Designing for Shared Cognition in Air Traffic Management

It is to be expected that the task of an air traffic controller will change with the introduction of four-dimensional (space and time) trajectories for aircraft, as can be seen in ongoing developments in air traffic management (ATM) systems in Europe (SESAR) and the US (NextGen). It is clear that higher levels of automation will need to be developed to support the management of four-dimensional trajectories, but a definite concept on a distribution of the roles of automation and human users has not yet been well defined. This paper presents one approach to the design of a shared representation for 4D trajectory management. The design is based on the Cognitive Systems Engineering framework and by using a formative approach in the analysis of the work domain, a step-wise refinement in the planning and execution of 4D trajectories is proposed. The design is described in three Abstraction Hierarchies, one for each phase in the refinement. The ultimate goal is to design a shared representation that underlies both the design of the human-machine interface and the rationale that guides the automation. It is foreseen that such a shared representation will greatly benefit the shared cognition in ATM and allows shifting back and forth across various levels of automation. A preliminary version of a joint cognitive system for 4D trajectory management has been developed and will be introduced in this paper. Further work will focus on the refinement of the shared representation by means of human-in-the-loop experiments.

Theoretical Foundations of an Ecological Synthetic Vision Display

This paper presents the conceptual design of an ecological Synthetic Vision Display. It is hypothesized to promote pilot terrain awareness and support decision-making by means of functional overlays that show pilots how their maneuvering possibilities are constrained by their own aircraft performance and surrounding terrain. Adopting an ecological approach to interface design, this paper integrates several aspects of previous research in managing the aircraft’s energy state and in pilo t terrain awareness. These enhancements are designed to effectively deal with terrain conflict situations while preserving the freedom of maneuvering as much as possible. This is different from current approaches explored by the synthetic vision community that aim at developing advanced alerting algorithms, which usually provide explicit resolutions to circumvent terrain conflicts. The resulting ecological display serves as an ext ernalized mental model that should allow pilots to link the internal aircraft energy management and maneuvering constraints to the external terrain constraint and reason on them appropriately. Whereas the theoretical foundations are discussed herein, a companion paper presents the results of an experimental evaluation.

Effects of transparency on the acceptance of automated resolution advisories

To lower the workload and increase the productivity of air traffic controllers in future scenarios, decision-support systems that functions on a higher level of control authority would be desired. However, increasing the control authority of automation asks for some important considerations in terms of design to ensure effective human-machine coordination. One of the factors that is hypothesized to affect human-machine collaboration, and one that is often overlooked in the design of such systems, is the solution transparency offered by the automated system. That is, when an automated system reveals some of its inner workings, it is expected to promote better system understanding and an increased acceptance of resolution advisories offered by that system. To this end, this paper investigates the effects of automation transparency on the acceptance of automated resolution advisories in conflict detection and resolution task for air traffic controllers. An exploratory experiment, featuring twelve aerospace students, was performed to study these effects. The results indicated that no main effects of transparency on acceptance were found, but also that there was a significant interaction effect between conflict geometry and transparency. For future research, an experiment is proposed with professional air traffic controllers and a larger sample size to increase the power of the statistics.

Assisting Air Traffic Controllers in Planning and Monitoring Continuous-Descent Approaches

An interface was developed to assist controllers in metering, sequencing and merging aircraft flying a Continuous Descent Approach. This Time-Space Diagram displays predicted aircraft approach trajectories in a way that allows controllers a better insight into the separation between aircraft flying continuous descents. The paper discusses how a baseline Time-Space Diagram display can be enhanced with ‘whatif’ predictions, providing support for routine controller spacing techniques such as speed instructions and the use of direct-to commands. An experiment with eight professional air traffic controllers compared the Time-Space Diagram to a conventional plan view display in low and high traffic rate scenarios. Use of the Time-Space Diagram display yielded a significant reduction in controller workload. It also reduced the number of instructions to the pilots, suggesting a reduced workload for the flight deck as well. Controllers’ opinions on the usefulness of the ‘what-if’ predictions were mixed, and these additions did not lead to any significant performance improvements.

Experimental Evaluation of an Ecological Synthetic Vision Display

Recent studies in interface-mediated situation awareness claim that an ecological approach to interface design can be a good foundation to support successful decision-making, even in unanticipated situations. It is also claimed to serve well as a teaching tool that can promote a deeper understanding of the work domain dynamics. Although previous studies in pilot terrain and traffic awareness support these claims, the results of pilot-in-the-loop evaluations did not always reveal that t he improved situation awareness and decision-making could be fully attributed to the ecological interfaces. The experiment designs compared them to conventional pilot interfaces, which were not always designed for the same purpose. In this paper an extensive pilot-in-theloop experimental evaluation of an Ecological Synthetic Vision Display, described in the companion paper, will be presented that aims to make fair comparisons with respect to a viable design alternative. Furthermore, it also aims to test the above-mentioned claims. The pilot-in-the-loop experiment, using sixteen glass-cockpit pilots in a fixed-based flight simulator, showed that the ecol ogical overlays indeed improved the overall pilot terrain awareness and decision-making in unanticipated events as compared to a command-based interface counterpart. The utility of the energy angle was found to be most important for recognizing off-normal events. However, for short-term collision avoidance, flight safety in terms of low altitude flying, and pilot workload the results are in favor of the command display. Despite these results, none of the pilots crashed when using the ecological display and the majority of them preferred it.

Development and Experimental Evaluation of a Performance-Based Vertical Situation Display

Advanced terrain warning systems, like the Enhanced Ground Proximity Warning System (EGPWS), and safety enhancing displays, like the Synthetic Vision System (SVS), have proven to reduce the number of Controlled Flight Into Terrain (CFIT) accidents considerably. Warning systems typically do not solve the cause of CFIT, but only treat the consequences . Safety enhancing displays provide an increase of situational awareness and thus target the main cause of CFIT: loss of situational awareness. Research indicated, however, that CFIT may still occur for aircraft equipped with these types of systems. In order to really increase the terrain awareness and prevent CFIT, the aircraft warning and safety systems should be more integrated. This paper presents the development and experimental evaluation of a Vertical Situation Display (VSD), integrated with terrain and aircraft performance information. On this VSD the maximum and minimum vertical maneuver capabilities of the aircraft are displayed, which are predicted with the use of the energy status, energy management and performance limitations of the aircraft. Besides knowing the aircraft vertical position relative to the terrain, the pilot will also know whether (according to the aircraft’s energy status) and how (depending on the performance limitations) he is able to avoid encountering objects in the vertical plane. An experimental evaluation, conducted in a fixed-base simulator, indicated that the VSD with integrated terrain and aircraft performance information increased the pilot’s (vertical) spatial awareness, decreased pilot workload and increased safety.

Fly-by-Wire and Tunnel-in-the-Sky Displays: Development and Experimental Evaluation of a Path-Oriented Control Augmentation

One of the objectives of the tunnel-in-the-sky display, a perspective flight-path display that shows the future trajectory to be flown by means of a three-dimensional tunnel, is to allow for accurate flying of complex curved trajectories. However, flight tests showed that pilots were unable to accurately follow the circular segments of those trajectories with a suitable workload in the presence of a strong crosswind. This paper provides the design rationale and experimental evaluation of a task-oriented display/control augmentation system that uses a wind compensation technique. The goal is to develop a path-oriented control augmentation in which the pilot commands the future trajectory of the aircraft. Results from the experiment, conducted in a fixed base simulator, indicate that the current implementation of this path-oriented control augmentation improves the path-following performance, but increases the pilot workload as compared to the Flight-Path Predictor display augmentation and Flight-Path Vector oriented fly-by-wire control augmentation.

Solution-Space–Based Analysis of Dynamic Air Traffic Controller Workload

Air traffic controller workload is considered to be a limiting factor to air traffic growth. Previous research introduced the static solution space approach to assess the difficulty of aircraft merging tasks. In this paper the dynamic, tangent-based solution space will be introduced that includes the future trajectory intent of all aircraft. Metrics derived from the solution space, together with common metrics, were tested for correlations with controller workload. An experiment has been conducted where subjects were required to line up all aircraft in a sector towards a certain waypoint, while periodically rating their workload. High correlations were found between several solution space related metrics and subjective workload ratings. In contrast to the number of aircraft metric, which had the highest correlation with workload, the dynamic solution space may allow for controller workload prediction in real-time.

The Use of Intent Information in Conflict Detection and Resolution Models Based on Dynamic Velocity Obstacles

The velocity obstacle (VO) representation, a mathematical representation that supports separation assurance for autonomous vehicle navigation, can provide improved performance when the intended trajectory (intent) of the involved vehicles is shared among each other. This paper proposes a fully analytical closed mathematical form for VOs as an intuitive and flexible calculation method, which is able to incorporate time-varying concepts such as trajectory prediction errors. Several study cases for specific traffic situations are explored, and possibilities to extend the method to the third dimension are discussed. Analysis showed that the calculation of the VOs with intent information could show self-curve intersections when maneuvers at close distance are required. Further elimination of these intersections might be necessary for certain specific applications.