Abstract
Rotational motions of the forearms, called pronation and supination, are applied to various operations of working, daily living, and sports. However, they are not incorporated into digital human models (DHMs) that perform visual and kinematic evaluations for usability of products and workability in workspaces with 3-dimensional CAD data. The forearms in the most of the DHMs are represented by one skeletal frame, even though the real human forearm contains two bones named ulna and radius. The objective of the study is to propose a 3-dimensional skeletal model of the human upper limbs consisting of the upper arms, forearms and wrists, which are applicable to simulation of the rotational motions of the forearms with high fidelity. In particular, emphasis is given to modeling of the inner structures of the forearms including two bones, i.e. the ulna and radius. The right forearms of three healthy male subjects are CT-scanned in every four rotational positions with no rotational torque, in order to analyze in-vivo 3-dimensional kinematics of the ulna and radius. In this study, the rotational axis of the forearms are firstly discussed based on the 3-dimansional images obtained from the CT-data. A 3-dimensional skeletal model is proposed to represent and simulate the motions of the human upper limbs including the rotational motions of the forearms.
