A Head-Driven Algorithm for Estimating Upper and Lower Body Motion in Virtual Reality Environments

This study proposes a novel algorithm for effectively estimating partial upper and lower body movements in a Virtual Reality (VR) environment using only head movements and synchronized head rotation axes, without the need for additional hardware. The proposed algorithm calculates the angle between the avatar’s pelvis and the head rotation axis to naturally reproduce the user’s upper body inclination and lower body bending. Notably, it offers the advantage of efficiently utilizing limited computational resources in multiplayer environments. The experiment was conducted in two stages. In the first stage, the objective performance of the algorithm was evaluated by comparing it with ground truth inclination data. In the second stage, participants performed two types of games (e.g., a dodgeball game and a limbo game) to assess their sense of immersion and embodiment. The objective results demonstrated that the proposed algorithm accurately and naturally expressed upper and lower body movements. Additionally, post-experiment surveys indicated that participants reported a high level of immersion and a natural interaction experience. This study presents a cost-effective solution for tracking upper and lower body movements in VR environments without requiring additional hardware, significantly enhancing the immersion of the VR experience. Future research will explore the expansion of the method to include upper body rotation estimation and full-body motion tracking, incorporating user locomotion.