Vector analysis of electrogastrography during motion sickness

Electrogastrography in Autonomous Vehicles-An Objective Method for Assessment of Motion Sickness in Simulated Driving Environments

Autonomous vehicles are expected to take complete control of the driving process, enabling the former drivers to act as passengers only. This could lead to increased sickness as they can be engaged in tasks other than driving. Adopting different sickness mitigation techniques gives us unique types of motion sickness in autonomous vehicles to be studied. In this paper, we report on a study where we explored the possibilities of assessing motion sickness with electrogastrography (EGG), a non-invasive method used to measure the myoelectric activity of the stomach, and its potential usage in autonomous vehicles (AVs). The study was conducted in a high-fidelity driving simulator with a virtual reality (VR) headset. There separate EGG measurements were performed: before, during and after the driving AV simulation video in VR. During the driving, the participants encountered two driving environments: a straight and less dynamic highway road and a highly dynamic and curvy countryside road. The EGG signal was recorded with a proprietary 3-channel recording device and Ag/AgCl cutaneous electrodes. In addition, participants were asked to signalize whenever they felt uncomfortable and nauseated by pressing a special button. After the drive they completed also the Simulator Sickness Questionnaire (SSQ) and reported on their overall subjective perception of sickness symptoms. The EGG results showed a significant increase of the dominant frequency (DF) and the percentage of the high power spectrum density (FSD) as well as a significant decrease of the power spectrum density Crest factor (CF) during the AV simulation. The vast majority of participants reported nausea during more dynamic conditions, accompanied by an increase in the amplitude and the RMS value of EGG. Reported nausea occurred simultaneously with the increase in EGG amplitude. Based on the results, we conclude that EGG could be used for assessment of motion sickness in autonomous vehicles. DF, CF and FSD can be used as overall sickness indicators, while the relative increase in amplitude of EGG signal and duration of that increase can be used as short-term sickness indicators where the driving environment may affect the driver.

Lessons Learned: Gastric Motility Assessment During Driving Simulation

In the era of technological advances and innovations in transportation technologies, application of driving simulators for the investigation and assessment of the driving process provides a safe and suitable testing environment. Although driving simulators are crucial for further improvements in transportation, it is important to resolve one of their main disadvantages–simulator sickness. Therefore, suitable methods for the assessment of simulator sickness are required. The main aim of this paper was to present a non-invasive method for assessing simulator sickness by recording gastric myoelectrical activity–electrogastrography. Open-source hardware for electrogastrography together with recordings obtained in 13 healthy volunteers is presented, and the main aspects of signal processing for artifact cancellation and feature extraction were discussed. Based on the obtained results, it was concluded that slow-wave electrical gastric activity can be recorded during driving simulation by following adequate recommendations and that proposed features could be beneficial in describing non-ordinary electrogastrography signals.

[Application of electrogastrography to public health]

In general, gastrointestinal motility tests cause pain; therefore, the establishment of noninvasive methods is desired. Noninvasive methods facilitate the measurement of motility close to the normal physiological state, can provide new findings, and may contribute to the development of associated fields. Electrogastrography (EGG) is a gastrointestinal motility test in which gastrointestinal electric activity is measured. Compared with other gastrointestinal motility measurement methods such as the gastric emptying and internal pressure measurement methods, EGG is noninvasive and allows measurement under minimum restriction; therefore, measurement for a long time is also possible. In addition, since gastrointestinal electric activity, which cannot be quantified using other methods, can be measured, EGG is applicable to the evaluation of the state of the body and pathological conditions, and may provide new findings such as those useful for the prevention of gastrointestinal dysfunction associated with various disorders. EGG is also useful for preventing disorders associated with abnormal gastrointestinal activity such as functional dyspepsia, which has been more frequently observed in recent years, and constipation, which is an extremely frequent complaint in the elderly. Thus, EGG is of marked importance in public health. However, the range of EGG utilizations and applications is still limited at present. Therefore, we outlined the measurement/analysis methods, the advantages and problems of EGG and electrogastroenterography (EGEG), described their clinical importance, and also commented on forefront studies on EGG and evaluated its prospects.

Motion sickness

PURPOSE OF REVIEW

The public's longstanding resigned tolerance to motion sickness threatens to change, due to the widespread introduction of nauseogenic tilting trains and the increasing use of virtual reality immersion.

RECENT FINDINGS

Scientific effort over the last 5 years has focused on precise evaluation of the stimuli that provoke sickness and on the development of behavioural and new pharmacological interventions to suppress sickness.

SUMMARY

The precise mechanical ride characteristics of vehicles that provoke sickness have been identified and this will lead to guidelines for future engineering design, especially for suspension systems that compensate for inertial tilt, and recommendations for passengers at risk. The frequency characteristics of motion provoking sickness have been defined with greater precision and identified with shifts in perception of motion versus orientation, and changes in the quality of reflex eye movements. Ability to modify readily the time constant of vestibular 'velocity store' has emerged as a potential candidate marker of successful motion sickness habituation. Behavioural 'autogenic' countermeasures to the development of sickness, such as controlled breathing, which can be implemented readily, are shown to have significant ameliorating effects on nausea and are of value for short term moderate exposures. New classes of pharmacological agents such as N-methyl-D-aspartate antagonists and 5HT1a receptor agonists show promise in animals but await trials in humans.