Understanding Perspectives for Single- and Multi-Limb Movement Guidance in Virtual 3D Environments

Design Space of Visual Feedforward And Corrective Feedback in XR-Based Motion Guidance Systems

“…In this paper, we want to focus on motor skill training and dissociate this work from complex tool handling [6], assembly tasks [42], or delicate professional skill training [41]. Elsayed et al [15] classified motion guidance into three main groups: (1) posture guidance, which involves providing clear visualizations of target postures at specific frames; (2) path guidance, which focuses on directing trainees' body movements along predefined paths in a 3D space; (3) movement guidance, which offers clear posture visualizations at each progressive frame along the path. In this paper, we will comprehensively explore motion guidance that encompasses all of the aforementioned concepts in the context of XR, and reclassify XR-based motion guidance based on our design dimensions (Section 4.5).…”

“…XR research often considers how a user's perspective of the (virtual) world and its content influences their behavior, and this is no different for motion guidance [15,59]. By varying the viewing perspective of the trainee relative to the feedforward, their perception of both the feedforward and of their own body changes, thus influencing their understanding and execution of the desired motions (Figure 2c).…”

“…In XR, this is typically a virtual coach using pre-recorded motion sequences such as to learn Tai-Chi [23], but can also be the virtual avatar of a remote trainer providing live motion guidance [26]. While distancing the trainee from the motion itself, the third-person perspective provides an exocentric view of the entire motion, thus promoting a more complete understanding of all facets of the motion-especially for motions involving multiple limbs [15].…”

“…Their "figurative" representation refers to movements presented as a humanoid body, which should be covered by our explicit feedforward. Second, the classification by Elsayed et al [15] on different types of motion guidance, already described in Section 2.1. In it, "posture guidance" refers to discrete explicit, "path guidance" refers to a subset of implicit guidance, and "movement guidance" refers to a combination of continuous explicit and autonomous explicit guidance.…”

“…Additional feedback can also be employed to overcome some of the limitations that intuitive feedback has. For example, trainees may not even notice that their body is misaligned with the feedforward, particularly in multi-limb motions or errors made in the depth direction [15]. Therefore, considering additional corrective feedback (visual cues like color and arrows) can still be beneficial, which requires additional visual encodings.…”