Operator Support for Time-Critical Situations: Design and Evaluation

The ground control station (GCS) is a critical element in the control of unmanned aerial vehicles (UAVs). Important issues in designing a GCS concern the automation, autonomy and authority of operator support functions. The research described in this paper focuses on the design and evaluation of both operator support functions that act in the time-critical domain and the graphical user interface of the GCS. The operator support functions are based on the current airborne collision avoidance system and terrain awareness warning system. Those algorithms have been extended to enable autonomous function execution. The evaluation has been done in two experiments. The objective of the first experiment was to explore the influence of the level of authority (LoA) assigned to the system on operator situational awareness (SA) and performance. The results of Experiment 1 showed no influence of LoA on operator SA and performance. Possibly, no differences between the LoAs were found, because user interventions occurred most often in the tactical time domain, whereas the autonomous functions operate in the time-critical domain. However, although participants had enough level 3 SA (projection of current state into the future) to timely detect conflicts, they often did not come up with a good solution for them. In these cases, the solution to one conflict directly caused a new conflict. It also occurred that participants misjudged a safe situation as an upcoming conflict, intervening when this was not necessary. In order to better support operator SA, the GCS displays were redesigned. A second experiment was conducted, investigating the effect of the modified displays and the influence of LoA on operator SA and performance. The results of this experiment showed no significant influence of LoA. With the modified displays, only one unnecessary intervention occurred, and not one solution to a conflict caused a new conflict. This led to the conclusion that the modified display design p- - rovided the participants with better terrain awareness (level 2 SA) and better level 3 SA in the vertical dimension