近年來虛擬實境技術的應用非常廣泛，可以利用虛擬實境模擬人員的任務，以輔助醫學上對於患者疾病的復健治療、遊戲或是職業訓練。
然而虛擬實境種類繁多，影響使用者知覺感受也不同。本研究主要目的在探討不同虛擬實境之呈現方式對於步態行為與主觀心理感受之影響。研究分成兩部分實驗：地面步態實驗與跑步機步態實驗。地面步態實驗中探討三種的不同的虛擬呈現方式 (Non-VR、Mono HMD、Stereo HMD) 對步態人員行走在地面之步態行為影響。跑步機之步態實驗中探討受試者在四種不同呈現方式 (Non-VR、Mono HMD、Stereo HMD、 Stereo Projector)與二個速度水準 (3.2 km/hr、4.7 km/hr)下對於步態行為之影響。本研究量測參數有下肢關節角度化與地面反作用力，並利用SSQ問卷量測虛擬環境的主觀不舒適度。
兩個實驗結果皆發現，呈現方式會對膝關節的矢狀面角度變化量與SSQ分數有顯著影響。在VR呈現方式 (Non-VR、Mono HMD、Stereo HMD或Stereo Projector)中，會有較大的膝關節角度變化量，且獲得較高的SSQ分數。在跑機步態實驗中，可以發現速度這項因子對於步態行為的影響力遠大於呈現方式與性別。在速度為4.7 km/hr時，有較短的步態週期時間與較大的髖、膝關節角度變化量。
另外，由本研究結果發現虛擬實境 (Mono HMD、Stereo HMD或Stereo Projector)影響人員的穩定度，此穩定度反應在膝關節角度變化量。在使用虛擬系統時需注意使用者的主觀不舒適度。

With the rapid development in information technology, the application of virtual reality becomes broader and more promising. By using virtual reality, it can easily simulate human tasks in virtual environment for medical rehabilitation, games, or professional training.
There are many different types of display techniques for virtual reality which may bring different perception to people. The primary purpose of this study was to examine the differences in gait parameters and subjective responses in different VR visual environment. The study was divided into two experiments: ground walking and treadmill walking. Twenty healthy adults participated the experiments. In ground walking experiment, subjects walked on a treadmill under three conditions (Non-VR, with Mono HMD, and Stereo HMD). As for treadmill walking experiment, subjects walked on a treadmill under four conditions (Non-VR, with Mono HMD, Stereo HMD, and Stereo Projector) at two walking speed, i.e. 3.2 and 4.7 km/hr. Response measures included joint range of motion in lower extremity and ground reaction force, and subjective motion sickness in virtual environment measured by the Simulator Sickness Questionnaire (SSQ).
From the results of the above two experiments, we found that the influence of VR visual environment has significant effect on the joint motion of knee and SSQ scores. The motion of knee and SSQ scores in VR environment (Mono HMD, Stereo HMD, or Stereo Projector) was found to be greater than that in Non-VR environments. In treadmill walking experiment, the influence of speed was greater than that of gender and VR visual display environment. At the speed of 4.7 km/hr, a shorter gait cycle and a larger motion in hip and knee joints was found.
Further the research found that VR environment had significant influence on the gait stability of the users. We should notice that the user’s motion sickness issue while applying VR equipment.

參考文獻
1. 周有禮，李正隆，江昇修，陳建忠，張維軍，林彥輝，陳詠心 (1996)。從防滑與保護足部的觀點探討勞工鞋的設計與製造。勞工安全衛生季刊，4(3)，1-17。
2. 吳家帆 (2006)。互動性虛擬實境之開發與應用-以生產作業為例. 國立清華大學工業工程研究所碩士論文。
3. Ames SL, Wolfesohn JS, and Mcbrien NA (2005). The development of a symptom questionnaire for assessing virtual reality viewing using a head-mounted display. Optometry and Vision Sciences, 82(3), 168-176.
4. Arnold P, Farrell MJ, Pettifer S, and West AJ (2002). Performance of a skilled motor task in virtual and real environments. Ergonomics, 45(5), 348-361.
5. Biocca F (1992). Will simulation sickness slow down the diffusion of virtual environment technology? Presence, 1, 334-343.
6. Borg G (1982). Psychophysical bases of perceived exertion. Medicine and Science in Sports and Exercise, 14, 377-381.
7. Cailliet R (1983). Foot and ankle pain. Philadelphia: F.A. Davis Company.
8. Chiu MC and Wang MJ (2006). The effect of gait speed and gender on perceived exertion, muscle activity, joint motion of lower extremity, ground reaction force and heart rate during normal walking. Gait & Posture, 25(3), 385-392.
9. Craik R (1989). Changes in locomotion in the aging adult. Woollacott MH.
10. DeLuca PA, Perry JP, and Ounpuu S (1992). The Fundamentals of Normal Walking and Pathological Gait. AACP & DM Inst, Course 2.
11. Ehrlich JA, Singer MJ, and Allen RC (1998). Relationships between head-shoulder divergences and sickness in a virtual environment. Proceedings of the Human Factors and Ergonomics Society 42nd Annual Meeting, 1471-1475.
12. Finley FR, Cody KA, and Sepic SB (1970). Walking patterns of normal women. Arch Physical Medical Rehabilitation, 51, 637-650.
13. Frenkel-Toledo S, Giladi N, Peretz C, Herman T, Gruendlinger L, and Hausdorff JM (2005). Effect of gait speed on gait rhythmicity in Parkinson’s disease: variability of stride time and swing time respond differently. Journal of NeuroEngineering and Rehabilitation, 2(23), 1-7.
14. Grieve D (1968). Gait patterns and the speed of walking. BioMedical Engineering, 3, 119-122.
15. Hale KS and Stanney KM (2006). Effects of low stereo acuity on performance, presence and sickness within a virtual environment. Applied Ergonomics, 37, 329-339.
16. Herman R, Wirta R, Bampton S, and Finley FR (1976). Human solutions for locomotion: Single limb analysis. Neural Control of Locomotion. New York: Plenum, 13-49.
17. Himann JE, Cunningham DA, Rechnitzcr PA, and Paterson DH (1988). Age related changes in speed of walking. Medicine & Science in Sports & Exercise, 20, 161-166.
18. Hollman JH, Robert HB, and Robb RA (2004). Spatiotemporal gait deviations in a virtual reality environment. Gait and Posture, 23(4), 441-444.
19. Howarth PA (1999). Oculomotor changes within virtual environments. Applied Ergonomics, 30, 59-67.
20. Howarth PA and Finch M (1999). The nauseogenicity of two methods of navigating within a virtual environment. Applied Ergonomics, 30, 39-45.
21. Inman VT, Ralston H, and Todd F (1981). Humna Walking. Williams & Wikins.
22. Iovine J (1995). Step into Virtual Reality. U. S. Windcrest: McGraw Hill Inc.
23. Jaeger BK and Mourant RR (2001). Comparison of simulator sickness using a static and dynamic walking simulator. Human Factors and Ergonomics Society 45th Annual Meeting, 1896-1900.
24. Kennedy RS, Lane NE, Berbaum KS, and Lilienthal MG (1993). Simulator sickness questionnaire: an enhanced method for quantifying simulator sickness. The International Journal of Aviation Psychology, 3(3), 203-220.
25. Keppell M and Macpherson C (1997). Is the elephant really there? –Virtual reality in education. http://www.ddce.cqu.edu.au/ddce/confsem/vr/present.html.
26. Kolasinski EM and Gilson RD (1998). Simulator sickness and related findings in a virtual environment. Proceedings of the Human Factors and Ergonomics Society 42nd Annual Meeting, 1511-1515.
27. Michael WW (1996). Gait Analysis: An Introduction. Oxford: Butterworth - Heinemann.
28. Mourant RR and Thattacherry TR (2000). Simulator sickness in a virtual environments driving simulator. The 10th Triennial Congress of the International Ergonomics Association, 534-537.
29. Murray M (1976). Gait as a total pattern of movement. American Journal of Physics, 46, 190-333.
30. Nichols S (1999). Physical ergonomics of virtual environment use. Applied Ergonomics, 30, 79-90.
31. Oberg T, Karsznia A, and Oberg K (1993). Basic gait parameters: Reference data for normal subjects, 10-79 of age. Journal of Rehabilitation Research and Development, 30(2), 210-223.
32. Oberg T, Karsznia A, and Oberg K (1994). Joint angle parameters in gait : Reference data for normal subjects, 10-79 years of age. Journal of Rehabilitation Research and Development, 31(3), 199-213.
33. Perry J and Schoneberger B (1992). Gait Analysis: Normal and Pathological Function. Slack Inc.
34. Rich CJ and Braun CC (1996). Assessing the impact of control and sensory compatibility on sickness in virtual environments. Proceedings of the 40th Human Factors and Ergonomics Society, 1122-1125.
35. Rose J and Gamble JG (2006). Human Walking: Lippincott Williams &Wilkins, 45-46.
36. Rose J and Gamble JG (2006). Human Walking: Lippincott Williams &Wilkins, 56-57.
37. Sheik-Nainar MA, Kaber DB, and McGee BD (2006). Optic flow during treadmill walking and the effect on gait kinematics. The 16th Triennial Congress of the International Ergonomics Association.
38. Shumway-Cook A and Woollacott MH (1995). Motor Control: Theory and Practical Applications. Baltimore: Williams & Wilkins.
39. Sparto PJ, Whitney SL, Hodges LF, Furman JM, and Redfern MS (2004). Simulator sickness when performing gaze shifts within a wide field of view optic flow environment: preliminary evidence for using virtual reality in vestibular rehabilitation. Journal of NeuroEngineering and Rehabilitation, 2004, 1-14.
40. Stanney KM and Kennedy RS (1998). The psychometrics of cyber sickness. Communications of the Association for Computing Machinery, 40(8), 66-68.
41. Stanney KM, Kennedy RS, Drexler JM, and Harm DL (1999). Motion sickness and proprioceptive after effect following virtual environment exposure. Applied Ergonomics, 30, 27-38.
42. Taylor AJ, Menz HB, and Keenan AM (2004). The influence of walking speed on plantar pressure measurements using the two-step gait initiation protocol. The Foot, 14(1), 49-55.
43. Thompson WB, Creem-Regehr SH, Mohler BJ, and Willemsen P (2005). Investigations on the interactions between vision and locomotion using a treadmill virtual environment. Proceedings SPIE/IS&T Human Vision & Electronic Imaging Conference, 5666, 481-492.
44. Viau A, Feldman AG, McFadyen BJ, and Levin MF (2004). Reaching in reality and virtual reality: a comparison of movement kinematics in healthy subjects and in adults with hemiparesis. Journal of NeuroEngineering and Rehabilitation, 2004, 1-11.
45. Winter DA (1984). Kinematics and kinetic patterns of human gait：Variability and compensating effects. Human Movement Science, 51-76.
46. Young SD, Adelstein BD, and Ellis SR (2006). Demand characteristics of a questionnaire used to assess motion sickness in a virtual environment. Proceedings of the IEEE Virtual Reality Conference, 44, 97-102.