ON THE BÊTA-ELLIPTIC MODEL FOR THE CONTROL OF THE HUMAN ARM MOVEMENT

Abstract

This article describes a kinematic theory, called the Bêta-elliptic model, for generating handwriting movements. The model consists of a sequential controller producing a curvilinear velocity approximated by Bêta profiles. This earlier interacts with a trajectory generator to provide elliptic strokes. As an application to our model, we consider a redundant seven degrees of freedom manipulator having a kinematic structure similar to that of a human arm. We treat to demonstrate how the Bêta-elliptic theory enables a simple motor program to generate complex curvilinear movements that have many of the properties that humans exhibit when they produce cursive script. Bêta-elliptic properties enable a simple control strategy to generate complex handwritten script if the hand model contains redundant degrees of freedom. Here, we restrict our analysis to a total of seven degrees of freedom from the shoulder to the wrist. The proposed controller launches transient commands to independent hand synergies at times when the hand begins to move. The Bêta-elliptic model transforms these synergy commands into smooth curvilinear velocity fitted by Bêta profiles among temporally overlapping synergetic units of trajectory approximated by elliptic strokes. In experiments, and at first sight, good phenomenological agreement with natural movement trajectories is found.