A description of billiard-ball collisions using a ‘discontinuous’ model is presented considering a two-step situation corresponding to the ball–ball interaction followed by ball-supporting surface interaction. It is applied to the inelastic impact of a cue ball having arbitrary pivotment and ‘English’ spins against an object ball initially at rest. This formulation provides a simplified approxi...

Detecting and localizing hard lumps in soft tissues is an important medical procedure. A psychophysics experiment measured minimum indentation forces required to detect a hard ball embedded in a soft rubber model. Ball size and finger indentation speed were varied. Threshold detection forces increased with ball size and decreased with indentation speed. The shape of the finger and contact press...

This paper propose a method to achieve wall juggling of a ball without rebound from a table by a racket attached to a robot manipulator with two visual camera sensors. The proposed method is composed of juggling preservation problem and ball regulation problem. The juggling preservation problem means going on hitting the ball iteratively. The ball regulation problem means regulating the hitting...

in this article we review an algebraic definition of the gyrogroup and a simplified version of the gyrovector space with two fundamental examples on the open ball of finite-dimensional euclidean space, which are the einstein and möbius gyrovector spaces. we introduce the structure of gyrovector space and the gyroline on the open convex cone of positive definite matrices and see its interest...

The authors’ aim in this work is to develop an easy-to-use computer-human interaction (CHI) platform. In this paper, i-ball 2 (interactive/information ball 2) is introduced as an attempt at the aim. i-ball 2 is a display-based interaction platform and designed to provide various interactive experiences, based on the concept of i-ball (an interactive display system which the authors’ group has d...

In this study, we develop a finite element model to examine the oblique soccer ball bounce. A careful simulation of the interaction between the ball membrane and air pressure in the ball makes the model more realistic than analytical models, and helps us to conduct an accurate study on the effect of different parameters on a bouncing ball. This finite element model includes a surface-based flui...

Measurements of the normal reaction force and the friction force acting on an obliquely bouncing ball were made to determine whether the friction force acting on the ball is due to sliding, rolling, or static friction. At low angles of incidence to the horizontal, a ball incident without spin will slide throughout the bounce. At higher angles of incidence, elementary bounce models predict that ...

The effectiveness of fastballs of equivalent speed can differ; for example, one element of this difference could be due to the effect of rate and orientation of ball spin on launched ball trajectory. In the present experiment, baseball batters' accuracy in hitting fastballs with different backspin rates at a constant ball velocity of 36 m/s was examined. Thirteen skilled baseball players (profe...