2011 Volume 4 Issue 2 Pages 114-119
Mapping from visual information to motor commands is an important issue in the study of voluntary arm movement. The joint kinematics of a human-like planar arm, which is generally described as a nonlinear function in a Cartesian coordinate system, can be approximately linearized in a head-centered polar coordinate system. This study shows that the mapping from the muscle lengths to the hand position in a head-centered polar coordinate system can also be approximately linearized. In addition, this study proposes a diagonalization of the kinematics that involves adjusting the moment arms of the muscles; in this diagonalization, the muscle lengths of two bi-articular muscles are proportional to the distance and direction from the head.