Muscle fatigue is a major impediment to the long-term usage and acceptance of Virtual Reality (VR). Users must routinely manipulate objects, perform repeated teleportations, and interact with user interface elements using prolonged arm and hand gestures. One leading strategy for reducing arm fatigue is ray-casting, which gives the user a laser pointer metaphor, allowing them to select objects with a comfortable position of the arms, but limits the fidelity of interactions by deviating from how hands are used in the real world. In this thesis a lesser-explored strategy to address arm fatigue is explored: hand redirection. “Hand redirection” is a technique made possible with VR, where the user can be fooled into believing their hand is in a different location to where it is in the real world, since people are visually dominant and VR completely immerses a person’s vision. Existing hand redirection literature mainly relates to being able to redirect the hand to a sparse haptic proxy, allowing the user to feel objects in VR, however its impact on arm fatigue is lesser explored.

In this thesis, hand redirection is explored as a practical mitigation strategy addressing arm fatigue in VR, which still supports natural hand interactions (unlike ray-casting). A system was built that provides hand tracking and a physical surface at different heights, such that the user can touch the lower or tilted surface, and still see themselves touching an upright surface at eye level in VR. A between-subjects study was then conducted with 48 participants across six conditions, using a 2×3 mixed-factorial design, with two levels of redirection (Tilted, Redirected) and a control (No Redirection), with (Present) and without (Not Present) a physical surface on which to tap.

The findings show that hand redirection is a valid way to reduce arm fatigue in VR, since arm fatigue was dramatically reduced without a significant impact on task performance. This behaviour differs when looking at results when the surface was present versus when it was not, suggesting that the way in which users behave in the presence of hand redirection is different when there is a physical surface to touch. Finally, the Tilted condition (where the board was rotated but not moved vertically) did not reduce arm fatigue, suggesting that the main way to reduce arm fatigue is to introduce a vertical offset rather than changing the angle that the hand interacts with the virtual content.