This paper presents a system that consists of three robots to imitate the motion of top volleyball blockers. In a volleyball match, in order to score by spiking, it is essential to improve the hitting percentage of each spiker. To increase the hitting percentage, iterative spiking training with actual blockers is required. Therefore, in this study, a block machine system was developed that can be continuously used in an actual practice field to improve attack practice. This robot performs high speed movement on 9 m rails that are arranged in parallel with the volleyball net. In addition, an application with a graphical user interface to enable a coach to manipulate these robots was developed. It enables the coach to control block motions and change the parameters such as the robots' positions and operation timing. Through practical use in the practice field, the effectiveness of this system was confirmed. In this paper, we describe the effectiveness to players through utilization of the system in actual practice. In addition, we clarify the improvement points exposed at that time, propose and construct a sensor system and describe its evaluation and future possibilities.
