Department of Physical Therapy, Movement, and Rehabilitation Science, Northeastern University, 360 Huntington Ave., Boston, MA, 02115, USA.
Department of Human Motor Behavior, the Jerzy Kukuczka Academy of Physical Education in Katowice, 72A Mikolowska St, 40-065, Katowice, Poland.
J Neuroeng Rehabil. 2019 Jun 27;16(1):78. doi: 10.1186/s12984-019-0525-9.
Virtual reality (VR) offers unprecedented opportunity as a scientific tool to study visuomotor interactions, training, and rehabilitation applications. However, it remains unclear if haptic-free hand-object interactions in a virtual environment (VE) may differ from those performed in the physical environment (PE). We therefore sought to establish if the coordination structure between the transport and grasp components remain similar whether a reach-to-grasp movement is performed in PE and VE.
Reach-to-grasp kinematics were examined in 13 healthy right-handed young adults. Subjects were instructed to reach-to-grasp-to-lift three differently sized rectangular objects located at three different distances from the starting position. Object size and location were matched between the two environments. Contact with the virtual objects was based on a custom collision detection algorithm. Differences between the environments were evaluated by comparing movement kinematics of the transport and grasp components.
Correlation coefficients, and the slope of the regression lines, between the reach and grasp components were similar for the two environments. Likewise, the kinematic profiles of the transport velocity and grasp aperture were strongly correlated across the two environments. A rmANOVA further identified some similarities and differences in the movement kinematics between the two environments - most prominently that the closure phase of reach-to-grasp movement was prolonged when movements were performed in VE.
Reach-to-grasp movement patterns performed in a VE showed both similarities and specific differences compared to those performed in PE. Additionally, we demonstrate a novel approach for parsing the reach-to-grasp movement into three phases- initiation, shaping, closure- based on established kinematic variables, and demonstrate that the differences in performance between the environments are attributed to the closure phase. We discuss this in the context of how collision detection parameters may modify hand-object interactions in VE. Our study shows that haptic-free VE may be a useful platform to study reach-to-grasp movements, with potential implications for haptic-free VR in neurorehabilitation.
虚拟现实 (VR) 作为一种研究视动交互、训练和康复应用的科学工具，提供了前所未有的机会。然而，目前尚不清楚在虚拟环境 (VE) 中进行无触觉的手-物交互是否与在物理环境 (PE) 中进行的交互有所不同。因此，我们试图确定在执行 PE 和 VE 中的伸手抓握动作时，运输和抓握组件之间的协调结构是否相似。
对 13 名健康的右利手年轻成年人进行伸手抓握运动的运动学分析。要求受试者伸手抓握并提起三个位于起始位置不同距离处的不同大小的矩形物体。在两个环境中匹配物体的大小和位置。基于自定义碰撞检测算法检测与虚拟物体的接触。通过比较运输和抓握组件的运动学来评估环境之间的差异。
在两种环境下，到达和抓握组件之间的相关系数和回归线斜率相似。同样，运输速度和抓握开口的运动学特征在两种环境下也具有很强的相关性。进一步的 rmANOVA 确定了两种环境下运动学的一些相似性和差异-最明显的是，在 VE 中进行伸手抓握运动时，抓握运动的闭合阶段会延长。
与在 PE 中进行的伸手抓握运动相比，在 VE 中进行的伸手抓握运动模式既有相似之处，也有特定的差异。此外，我们基于已建立的运动学变量提出了一种将伸手抓握运动分解为三个阶段的新方法-启动、塑造、闭合-并证明环境之间的性能差异归因于闭合阶段。我们在讨论碰撞检测参数如何改变 VE 中的手-物交互时讨论了这一点。我们的研究表明，无触觉的 VE 可能是研究伸手抓握运动的有用平台，对无触觉的 VR 在神经康复中的应用具有潜在影响。
