Chen Y C, Lee H J, Lin K H
Annu Int Conf IEEE Eng Med Biol Soc. 2015 Aug;2015:703-6. doi: 10.1109/EMBC.2015.7318459.
Range of motion (ROM) is commonly used to assess a patient's joint function in physical therapy. Because motion capture systems are generally very expensive, physical therapists mostly use simple rulers to measure patients' joint angles in clinical diagnosis, which will suffer from low accuracy, low reliability, and subjective. In this study we used color and depth image feature from two sets of low-cost Microsoft Kinect to reconstruct 3D joint positions, and then calculate moveable joint angles to assess the ROM. A Gaussian background model is first used to segment the human body from the depth images. The 3D coordinates of the joints are reconstructed from both color and depth images. To track the location of joints throughout the sequence more precisely, we adopt the mean shift algorithm to find out the center of voxels upon the joints. The two sets of Kinect are placed three meters away from each other and facing to the subject. The joint moveable angles and the motion data are calculated from the position of joints frame by frame. To verify the results of our system, we take the results from a motion capture system called VICON as golden standard. Our 150 test results showed that the deviation of joint moveable angles between those obtained by VICON and our system is about 4 to 8 degree in six different upper limb exercises, which are acceptable in clinical environment.
活动范围（ROM）在物理治疗中常用于评估患者的关节功能。由于运动捕捉系统通常非常昂贵，物理治疗师在临床诊断中大多使用简单的尺子来测量患者的关节角度，这会存在准确性低、可靠性低和主观性的问题。在本研究中，我们利用两组低成本的微软Kinect的彩色和深度图像特征来重建三维关节位置，然后计算可动关节角度以评估活动范围。首先使用高斯背景模型从深度图像中分割出人体。关节的三维坐标从彩色图像和深度图像中重建。为了更精确地跟踪整个序列中关节的位置，我们采用均值漂移算法来找出关节上方体素的中心。两组Kinect相互间隔三米放置并面向受试者。逐帧根据关节位置计算关节可动角度和运动数据。为了验证我们系统的结果，我们将一个名为VICON的运动捕捉系统的结果作为金标准。我们的150次测试结果表明，在六种不同的上肢运动中，VICON获得的关节可动角度与我们系统获得的关节可动角度之间的偏差约为4至8度，在临床环境中这是可以接受的。
