Fig. 6
(A) An example snapshot taken by a high-speed camera during the ball release process under the no application condition. The time when the ball left the fingertips of the index and middle fingers was determined visually and set as the release time (t = 0.0 ms). (B) A schematic diagram of markers on the ball (P1–P5) and the center of the ball contour (P0). (C) A schematic diagram of markers on the ball and fingertips after coordinate transformation. The ball angular velocity ωball was obtained from the angles of 2 diagonals using the difference method. The position vector of the fingertip marker Pfinger to the ball center marker position P1 was calculated, and the relative angular velocity of the fingertip against the ball center ωfc was calculated.
