Indexed on: 01 Aug '05Published on: 01 Aug '05Published in: Multibody system dynamics
Described in this paper is a new kinetostatic model of the forearm axial motion, i.e., from supination (palm up) to pronation (palm down) and vice versa. The model features an elastokinematic coupling between axial displacement and lateral swaying of the humero-ulnar (elbow) articulation. Such an evasive axial and swaying motion of the ulna has been observed by various authors using magnetic resonance imaging (MRI). In this paper, a two-degree-of-freedom model is presented in which the swaying and axial motion of the ulna is controlled by static equilibrium via two corresponding virtual springs. The spring stiffnesses are identified from geometric measurements, such that the observed motions correspond to the simulated ones. This model can be later used for biofidelic computer-oriented surgery planning. The paper presents the basic kinematic and static relationships of the model as well as an implementation featuring on-line 3D rendering of the motion of the bones.