Fatigue Management Techniques

Description:

Mid-air pointing can be fatiguing. While interaction methods exist, that allow for mid-air pointing with less body movement or that enable movements at resting position, they are more abstract than direct pointing and may reduce the naturalness of the interaction. Therefore, this project investigates how the fatigue management methods affect the users' sense of embodiment and presence in VR. We implemented three fatigue assistance methods for mid-air pointing tasks in VR. SphereCast: Instead of a single ray, for the target selection happens through a sphere-shaped volume along the ray path. This methods requires less precision for the users' movements than a regular ray cast.

ProxyHand: Users can define an offset position for the ray's origin. This allows the user to perform pointing tasks while the arm is at a resting position

RadialSelect: The selection is performed using the analog stick on the controller instead of arm movements. The selection method projects the selection on a 2D plane and reduces the reduces the required motion to thumb movements.

Design Approach:

We conducted a within-subjects user study with 21 non-disabled participants who performed mid-air pointing tasks with regular pointing method (baseline) and the three implemented fatigue management techniques (SphereCast, ProxyHand and Radial Select). The study measured performance fatigue through Consumed Endurance along with subjective measures on workload, presence and embodiment. The results show that while the methods reduced fatigue during interaction, the increased deviation from the one-to-one mapping of the physical movement reduced the sense of presence and embodiment.

Implications for VR Experience:

These findings highlight the tension between assistive interaction methods and the users' experience in VR. This implies that effective fatigue management methods require a careful considerations of ergonomic advantages to retain immersive experiences in VR. However, these findings have been investigated with participants with no physical disabilities and should be confirmed with disabled participants.

Gallery:

Implementation Note:

The user study was implemented in Unity 6 using the standard OpenXR VR rig. To chose the interaction technique, select the XR Origin in the scene and under Assistance System Manager select the desired method from the dropdown. Alternatively, select TaskManager and press the Load Next Condition Button in the inspector. 

The source code is available upon reasonable request via mailto:accessvr∂iar.kit.edu.