Abstract
The following two characteristics have been well demonstrated about the feature of a point-to-point human arm movement on a plane. (1) The path is a roughly straight line, but is slightly curved. (2) The velocity profile is bell shaped with a single peak. Several models have been proposed to explain these features. Four criteria for trajectory planning based on optimal principles have been proposed. They were the minimum hand jerk criterion, the minimum angle jerk criterion, the minimum torque change criterion, and the minimum commanded torque change criterion. It has shown that trajectories generated by the minimum commanded-torque change model correspond well with measured trajectories in a horizontal and sagittal work space. In the paper, we measured point-to-point movements in three-dimensional space and performed comparative examinations quantitatively between arm posture planned by the optimal criterion and measuerd arm posture. Next, we performed comparative examinations between the measured trajectories and the optimal trajectories based on minimum angle jerk criterion, minimum torque change criterion and minimum commanded torque change criterion. Finally, we report that both of the measured hand trajectory and arm posture were closest to the trajectory and posture predicted by the minimum commanded torque change criterion.
