Operator Engagement During Prolonged Simulated UAV Operation

Unmanned aerial vehicle (UAV) operation is demanding in terms of attentional resources' engagement. As systems grow more automated, the operators are placed in long monitoring phases most of the time. Although UAV operators' fatigue state has been extensively assessed at the behavioral and oculomotor levels, to our knowledge there is a lack of literature regarding potential cardiac and cerebral markers. Therefore, this study was designed to investigate which markers of operators' engagement could be used for mental state estimation in the context of UAV operations. Five volunteers performed a UAV monitoring task for two hours without any break. The task included an alarm monitoring task and a target identification task using a joystick. Only ten alarms occured during the session, amongst which only seven required an identification from the operator. The investigated markers were of oculomotor (eye-tracking), cardiac (ECG) and cerebral (EEG) origin. In addidtion to a significant modulation of the alpha power, the blink rate and the number of fixations with time-on-task, the main results are a significant correlation of response times with both the cardiac Low Frequency / High Frequency ratio and the number of ocular fixations.