Effect of time-delay on lunar sampling tele-operations: Evidences from cardiac, ocular and behavioral measures

The purpose of this study is to quantify performance in human-robot interaction under time-delay conditions in a lunar tele-operations sampling task, by testing the hypothesis that an increase of time-delay would lead to higher perceived workload and lower human performance in human-robotic integrated operations. Tele-operation is key in the exploration of the Moon, and allows for robotic elements to be controlled from orbital infrastructure and other planetary bodies such as the Earth. Considering that future missions aim to control rovers (amongst others for sampling tasks) from Earth (delay: 3s), the Gateway (delay: 0.5s) and the Moon (delay: 0s), control under the time-delay conditions for these locations must be studied. Time-delay can affect performance, and understanding the performance means that mission operations can be planned bottom-up, which benefits both the preparation of the crew and the design of rovers. An experiment was conducted with 18 engineers who were assigned to control a robotic arm under three time-delay conditions, representing the three control locations. Several metrics were derived from cardiac, ocular, subjective and behavioral measures. The analyses disclosed that the large time-delay condition statistically increased the perceived workload, the time to complete the mission and decreased heart rate variability compared to the other conditions. However, no effect of time-delay was found on attentional and executive abilities. The metrics proved to be effective in the study of performance quantification in human-robot interaction for tele-operations in lunar control scenarios. This approach can be implemented for a larger range of robotic activities, such as tele-operated driving.