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Can an ergometer based virtual reality environment reproduce typical real-world wheelchair manoeuvring?

  • Author / Creator
    Salimi, Zohreh
  • Virtual reality together with a wheelchair ergometer provide the perfect setting for conducting research involving wheelchair users, rehabilitation for inexperienced wheelchair users, and training wheelchair athletes. The target of this study was to develop a wheelchair ergometer-based virtual reality system that could mimic the biomechanics of real-world wheelchair manoeuvring. In an attempt to do so, a linear inertia system based on a roller ergometer was built based on a thorough biomechanical analysis, and was further equipped with a cube virtual reality environment. In addition, in a developmental manner, three approaches were taken to simulate wheelchair turning, forming three final systems. System I only accommodates linear inertia, assuming the additional inertial effects associated with rotation can be neglected, while system II and III provide compensation for rotational inertia, mechanically and perceptually, in addition to linear inertia. The mechanical system uses a pneumatic braking to add real time resistance against turning, while system III slows down the rotations in virtual reality, corresponding to the rate of turning that happens in the real world where rotational inertia is present. To test the validity and reliability of the systems developed, 15 able-bodied participants were recruited, each performing a series of Illinois agility tests both in RW and in the VR environment. The test-retest reliability of using this agility test was also examined in this study, based on a comprehensive biomechanical analysis assessing 53 variables in total. 94% of the variables tested showed good to excellent ICC, and none of the single-value parameters tested showed a meaningful difference from session one to session two, where the two sessions were at least one week apart (10 days in average). The main objective of this study was to show the reliability and validity of the virtual reality systems developed. Since inexperienced, able-bodied persons using a wheelchair are less likely to be consistent in the way they propel a wheelchair, recruiting them for this study was justifiable. If we could show that inexperienced wheelchair users were consistent from one session to another, and between real and virtual worlds, we could also assume that experienced wheelchair users would also be consistent between these two environments. Test-retest reliability and construct validity of the three systems were examined, using, respectively, ICC for VR systems tried in two different sessions, and Pearson correlation between the data obtained from VR system tests and real-world tests, conducted in the same session. 53 biomechanical variables were tested in total, and as a result, all three systems showed good validity for many of the variables tested. Also, a very good reliability for the System II and good reliability factors for Systems I and III was observed for most of the variables tested. In general, System II was biomechanically the best system while System III delivered a better VR experience. This study also revealed that to finish a manoeuvring task in VR, people use more time, shorter pushes, less pushes, more tangential forces, and less backward pushes relative to real world. To prepare the participants for the experiments, they underwent up to four training sessions to acclimatize to motion sickness. The results of this study showed that a maximum of four sessions held on different days was enough to resolve motion sickness or reduce the susceptibility to it to a well tolerated level. Furthermore, the Motion Sickness Assessment Questionnaire and the Igroup Presence Questionnaire were used to assess participants’ motion sickness and feeling of presence in the VR. It was observed that all of the three systems presented relatively low motion sickness and high virtual presence. Also, a meaningful inverse relationship between motion sickness and VR presence was observed.

  • Subjects / Keywords
  • Graduation date
    Fall 2017
  • Type of Item
    Thesis
  • Degree
    Doctor of Philosophy
  • DOI
    https://doi.org/10.7939/R3BG2HS21
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.