Dexterity evaluation of a hitting skill considering motion latitudes before impact

This paper proposes an evaluation method for human hitting motion skill. The hitting motion is one of basic motions, in which a human often employs a tool to move or convert an object. Also, hitting skill is an important performance desired in many sports, such as tennis and baseball, and also in the field of traditional crafts, such as nailing and forging. In proposed method, the hitting skill using some tool is analyzed from its dynamical characteristics. When conducting a hitting skill, ideal impulsive force is added in a certain direction at specific point to obtain desired result. To add the impulsive force in such a way, human controls trajectory and velocity of the tool before impact. Therefore, the way how human controls the tool trajectory and velocity before impact is analyzed in this paper. Concretely, the hitting skill is evaluated considering trajectory latitude and velocity latitude of the tool before impact. These indexes give how much spatial and temporal latitudes human has in skill conducting, and show two dominant aspects of hitting dexterity. The proposed method is applied to the evaluation of a pocket billiard stroke motion. For the experiment, constructed billiard robotic system with two degrees of freedom is utilized. The experimental results suggest even with the same result, computed dexterities show deeper evaluation for the skill motions.