Paddle Juggling of one Ball by Robot Manipulator with Visual Servo

This paper proposes a method to achieve paddle juggling of a ball 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 maintenance problem means going on hitting the ball iteratively. The ball regulation problem means regulating the position and orientation of the hit ball. The juggling preservation problem is achieved by the tracking control of the racket position for a symmetry trajectory of the ball with respect to a horizontal plane. The ball regulation problem is achieved by controlling the racket orientation, which is determined based on a discrete transition equation of the ball motion. The effectiveness of the proposed method is shown by an experimental result

I. Introduction

Paddle juggling of balls is a typical example to represent dexterous tasks of humans, and is interesting and difficult to be realized by robots. The paddle juggling of a ball by a racket is composed of three parts: the first part is to iterate hitting the ball, the second part is to regulate the incident angle of the ball to the racket, and the third part is to regulate the hitting position and the height of the hit ball. M. Buehler et. al. [1] proposed the mirror algorithms for the paddle juggling of one or two balls by a robot having one degree of freedom in two dimensional space, where the robot motion was symmetry of the ball motion with respect to a horizontal plane. This method achived hitting the ball iteratively. R. Mori et. al. [3] proposed a method for the paddle juggling of a ball in three dimensional space by a racket attached to a mobile robot, where the trajectory of the mobile robot was determined based on the elevation angle of the ball. This method achieved hitting the ball iteratively and regulating the incident angle. These algorithms are simple and effective for hitting the ball iteratively. However, their method does not control the hitting position and the height of the ball. On the other hand, S. Schaal et. al. [2] proposed a open loop algorithm for one-dimensional paddle juggling of one ball. S Majima et. al. [4] proposed a method for the paddle juggling of one ball with the receding horizon control base on the impulse information of the hit ball. Their methods achived regulating the height of the ball. However, the control problem is only considered in one dimensional space.