Reducing Arm Fatigue in Virtual Reality by Introducing 3D-Spatial Offset

Arm fatigue is an important factor affecting user experience in Virtual Reality (VR). In this work, we have proposed ProxyHand and StickHand, virtual hand techniques to address this issue. Using ProxyHand or StickHand, users can flexibly adjust the 3D-spatial offset between the physical hand and its virtual representation. This will allow users to keep their arms in a comfortable posture (vertically down) even when they have to manipulate objects in locations that require lifting of arms using the default interaction method. Proposed ProxyHand and StickHand have a similar Underlying concept that is to introduce a 3D-spatial offset between the physical hand and its virtual representation in VR. However, they respond differently to the user's hand movements because of different working mechanisms. Question arises whether the 3D-spatial offset will negatively impact the hand control ability as the directness of interaction is being violated. To investigate this, we conducted user studies where users were asked to perform object translation, rotation and hybrid tasks. ProxyHand and StickHand are used in combination in some scenarios to maximize positive impact on the user experience in VR. This raises the question to find the best possible combination of these virtual hands to reduce arm fatigue. Firstly, for this purpose, we combined both virtual hands by manually allowing users to switch between ProxyHand and StickHand. Secondly, we used machine learning to automatically switch between both the virtual hands. Results showed that introduction of a 3D-spatial offset largely reduced the arm fatigue while offering equal performance to the default interaction method for all these tasks; translation, rotation and hybrid task. Users preferred using ProxyHand and StickHand to interact in the VR environment for longer periods of time.