The Effects of Different Visual Slope Gradients on Kinematics in Virtual Reality Walking

  • Stoycho Velchev Velev

    Student thesis: Doctoral Thesis

    Abstract

    Abstract
    There are a number of conditions that leave people with reduced mobility, such as post stroke, trips, falls and some neurological disease. Traditional walking rehabilitation requires adherence to repeatedly walking within a controlled environment. Virtual Reality has been used in this context and has shown that Virtual Environments have a positive effect on walking gait, via an increase in motivation and adherence. These Virtual Environments, however, are typically used for visual interest and there is little discussion about the different design features, such as slopes, obstacles, colour or the general environmental choices. Slopes are interesting as approaching physical slope presents with changes in walking gait and virtual slopes may instigate a change in walking behaviour that could support and increased rehabilitation effect. However, a systematic exploration of the visual slopes within the Virtual Environments, has not been considered, with regard to their effects on walking gait. The aim of this thesis is to investigate how walking gait (gait kinematics and spatiotemporal parameters) is affected by different visual only slope gradients.
    Two empirical studies in Treadmill-Mediated Virtual Reality and Overground Walking in Head- Mounted Display based Virtual Reality, which manipulated visual slope gradients within the Virtual Environment, were conducted. The studies focused on investigating trunk, hip, knee, and ankle angles and overall walking speed. Study one used optical motion capture and a large screen projection display exploring different visual slope gradients on a continuous path. Participants were found to modify their walking gait, when approaching, and just moving onto a virtual slope (transitioning). Participants trunk leaned backwards when approaching the virtual slope, followed by a lean forward during the virtual slope. Furthermore, walking speed was found to consistently reduce when approaching the different slope gradients and an increase post transition, which may support walking rehabilitation.
    Following the first experiment as treadmill walking may have affected the results, the second experimental study used inertial motion capture and a Head-Mounted Display to explore transitioning to visual slope gradients, whilst overground walking. Participants were found to reduce their walking speed when approaching the virtual slope, witch was also observed with the increase in hip flexion and the increase in knee extension. Furthermore, the ankle angle
    seemed to follow the gradient of the virtual slope.
    The combined results from the two experiments suggest that participants were found to modify their walking gait, when approaching, and just moving onto a virtual slope (transitioning). These changes in gait kinematics (joint angles) are marginal in regard to possibilities to improve walking rehabilitation, as the effect operates in a limited space. However, the identification of a change in gait kinematics at that point, is significant, as previous studies have focussed on a much larger distance when treadmill walking. These results highlight a potential for negative changes in gait that may increase the chances of disbalance in a rehabilitation population, due to the visual and physical mismatch in the transition period. However, the results also highlight that a suitable adaptation effect might be useful as diagnostic post injury.
    Date of Award16 Dec 2024
    Original languageEnglish
    Awarding Institution
    • University of Portsmouth
    SupervisorBrett Stevens (Supervisor), Chris Mills (Supervisor) & Argenis Ramirez Gomez (Supervisor)

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