Background: Virtual reality (VR) programs based on motion capture camera are the most convenient and cost-effective approaches for remote rehabilitation. Assessment of physical function is critical for providing optimal VR rehabilitation training; however, direct muscle strength measurement using camera-based kinematic data is impracticable. Therefore, it is necessary to develop a method to indirectly estimate the muscle strength of users from the value obtained using a motion capture camera. Objects: The purpose of this study was to determine whether the pedaling speed converted using the VR engine from the captured foot position data in the VR environment can be used as an indirect way to evaluate knee muscle strength, and to investigate the validity and reliability of a camera-based VR program. Methods: Thirty healthy adults were included in this study. Each subject performed a 15-second maximum pedaling test in the VR and built-in speedometer modes. In the VR speedometer mode, a motion capture camera was used to detect the position of the ankle joints and automatically calculate the pedaling speed. An isokinetic dynamometer was used to assess the isometric and isokinetic peak torques of knee flexion and extension. Results: The pedaling speeds in VR and built-in speedometer modes revealed a significantly high positive correlation (r = 0.922). In addition, the intra-rater reliability of the pedaling speed in the VR speedometer mode was good (ICC [intraclass correlation coefficient] = 0.685). The results of the Pearson correlation analysis revealed a significant moderate positive correlation between the pedaling speed of the VR speedometer and the peak torque of knee isokinetic flexion (r = 0.639) and extension (r = 0.598). Conclusion: This study suggests the potential benefits of measuring the maximum pedaling speed using 3D depth camera in a VR environment as an indirect assessment of muscle strength. However, technological improvements must be followed to obtain more accurate estimation of muscle strength from the VR cycling test.

본 논문에서는 노인 및 재활 환자를 대상으로 재활 훈련을 위한 기능성 게임을 제안한다. 제안한 재활 훈련용 기능성 게임은 3D depth 카메라를 이용한 전신 동작 인식 기반의 인터페이스를 제공한다. 사용자가 카메라 앞에서면 배경과 사용자를 구분한 다음 사용자의 전신을 15개의 관절로 인식하고 각 관절이 위치와 방향의 변화를 분석하여 게임에 필요한 제스쳐를 인식한다. 게임 콘텐츠는 상지훈련, 하지훈련, 전신훈련, 밸런스 훈련을 위한 게임으로 구성하였으며 2D 게임과 3D 게임으로 나누어 구현하였다. 본 논문에서 제안된 시스템은 3D depth 카메라를 이용하여 주변 환경 변화에도 안정적으로 작동하며, 별도의 기기를 사용하지 않고도 전신 움직임 기반의 제스쳐 인식을 이용하여 게임을 진행하게 함으로써 재활의 효과를 높일 수 있다.