Abstract
This paper deals with the path planning of human digits in grasping a cylindrical object with the thumb and index finger. The trajectory of the thumb from initial position to the target could be divided into three patterns, a convex, double convexes, and non-convex type line. Moreover, the digit of thumb approached to the cylindrical object along to a tangential line with respect to the lateral of the object. Based on the obtained characteristics, the trajectory of thumb was approximated by the Bezier curve. As a result, it could be found that the distinctive patterns could be adequately expressed by the Three-order Bezier curve.
