Building Linkage Models of Human Arms

在这个项目中，我们开发了一种系统的方法，通过人体上臂的运动测量来建立人体上臂的个人链接模型。将三维位置传感器和柔性关节角度传感器应用于上臂运动和手腕运动的测量中，首先在上臂的连杆模型中引入了2连杆1自由度机构来描述人体肩部运动。需要估计链接模型中涉及的个人模型参数，以便该模型可以应用于个人。因此，我们建立了一种通过预先进行简单运动的测量来识别模型参数的方法。通过测量可以识别出两连杆一自由度机构中肩关节中心的位置、两个杆件的长度和两个关节角度之间的关系、肘关节中心的位置和前臂的长度等模型参数。传统的1连杆1自由度模型不能同时描述人手的位置和姿态，而所提出的模型能够简单地描述它们。另外，通过对模型参数的辨识，可以方便地将人与人之间的差异引入到链接模型中，消除传感器位置的差异。其次，我们开发了灵活的关节角度传感器来测量人体手腕的运动。由于手腕运动的范围较窄，我们发现3D传感器不适合手腕运动的测量。因此，我们有了使用应变计的角度传感器原型，并发现只要手腕角度在50度以下，它们就有足够的精度。如上所述，我们发现该方法对于建立人体上臂的个人模型是有效的。建立手腕模型是一个悬而未决的问题。

In this project, we have developed a systematic method to build a personal link model of human upper arms through their motion measurements. A3D position sensor and flexible joint angle sensors are utilized in the measurements of upper arm motion and wrist motion.First, we have introduced a 2-link 1-DOF mechanism into the link model of a upper arm to describe human shoulder motion. It is required to estimate personal model parameters involved in the link model so that the model can be applied into individual persons. Thus, we have established a method to identify model parameters through the measurements of simple motions performed in advance. Model parameters including the location of shoulder joint center, length of two links and the relationship between two joint angles in the introduced 2-link 1-DOF mechanism, the location of elbow joint center, and length of forearm can be identified through the measurements. Traditional 1-link 1-DOF models cannot describe the position and the orientation of human hand simultaneously while the proposed mode is capable of describing them in a simple manner. In addition, difference among individual persons can be taken into the link model easily as well as the difference of sensor locations can be eliminated through the identification of model parameters. Second, we have developed flexible joint angle sensors to measure human wrist motion. Since the range of wrist motion is narrow, we have found that the 3D sensor is inappropriate to the measurements of wrist motion. Thus, we have prototyped angle sensors using strain gauges and have found that they have sufficient accuracy as long as the wrist angle is under 50 degrees. As mentioned above, we have found that the proposed method is effective to build a personal model of human upper arms. Building wrist models is an open issue.