الفهرس 
INTRODUCTION AND REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Low ftequency vertical oscillation in the seated position can cause motion sickness in some rtation systems, but the influence of the characteristics of the motion like ftequency, litude and duration of oscillation are poorly understood. The effect of the IDthropometrical features as well as the effect of some habits and visual influences on lickness are not known. It was hypothesized that the motion p~eters and the different IUbjects’ susceptibility to motion sickness influence the degree of sickness. The goal of the present work is to measure critical motion parameters inducing motion sickness and relate them to the severity of the symptoms.
To properly achieve the goals of this study, a survey was conducted. This survey revealed certain facts about what motion sickness is, its causes, symptoms and remedies. On the other hand, the effects of motion were studied. Most of the researches dealt with the subjects on the standing position. Studying motion sickness on the seated position emerged only the last two years. Very few researchers worked experimentally, most studies were on-situ with motion sickness susceptibility questionnaires.
For the purpose of the present study, a chair with a low backrest, in its simplest form, hydraulically controlled, was manufactured to simulate vertical 0 scillations. The design 0 f this chair was based mainly on the fact that motion sickness occurs at very low ftequencies with the facility of choosing different preset ftequencies and amplitudes. A motion sickness questionnaire was used to record the impact of ftequency-amplitude-time patterns on the occurrence of symptoms.
Nine male subjects were selected with a previous motion sickness history. The subjects were exposed to vertical periodical oscillations while seated in a closed room with their eyes open for up to 60 minutes. A full factorial design was adopted to study the effect of different levels of ftequencies and amplitudes on motion sickness time. Sixteen conditions were involved at ftequency levels of 0.08, 0.15, 0.25 and 0.35 Hz while peak-to-peak amplitude was set at four different levels of 0.075, 0.15, 0.225 and 0.3 m
Subjects provided ratings of their motion sickness symptoms before undergoi experiments, after 5 minutes, after 10 minutes and at the end of the experiments stationary position.
The results showed that the frequency was statistically significant (p=0.082) w~ amplitude showed no significance. Qualitative results, symptoms frequency of OCCt highlighted the effect of the amplitude on motion sickness symptomatology. The fre results matched with the previous researches and with the ISO 2631 for being of ma influence around the 0.3 Hz.
On the other hand, the results showed that wearing glasses decreases the susceptit motion sickness and smoking increases that susceptibility. The stature and weight subject were found to have a significant effect on motion sickness syndrome.
The percentage occurrence of the symptoms over all subjects and all experiments sh fullness of head is the most dominant symptom (66.3%) while burping is the Ie (23.1 %)