Visually Induced Motion Sickness During Tele-Operation of an Excavator Simulator: Effects of Virtual Reality Devices and Operation Delay

The aim of this study is to clarify the characteristics of visually induced motion sickness (VIMS) during tele-operation of construction machinery using subjective and objective indicators. To clearly define and ensure the repeatability of the experiment conditions, we used virtual reality to simulate a real-world construction machinery tele-operation system. 90 people with no prior operating experience participated experiments under the experimental conditions of image presentation device and delay in reflecting operations in generated images. To evaluate visually induced motion sickness, we used body sway and the R-R interval, the ratio of low-frequency to high-frequency components (LF/HF), and the m and S indicators of Lorenz plots derived heart rate variability. In addition, subjective evaluation was performed using the simulator sickness questionnaire. We conducted a multifaceted analysis including interactions between time-series variation in operational performance and physiological indicators and subjective evaluations. In the operational performance results, the participants demonstrated reasonable learning effects while exhibiting negative effects of delays. The variation in body sway indicators among participants was too large to demonstrate the effects of operation delays. No effects of the experimental conditions were found when averaging the heart rate variability under the assumption that there is common time-series variation among the participants. A relation, however, was found between heart rate variability and the subjective symptom of sickness by using an indicator based on broader variation in heart rate variability. This is a finding that previous studies using similar experimental conditions for VIMS in tele-operation of construction machinery have not been able to demonstrate.