We developed a baseball pitching practice ball to provide the real-time visual feedback of the spin rate by changing the surface color according to the rotational speed of the pitch. This system eliminated the need for external display devices such as tablets or monitors, thereby reducing the system complexity and cost. Furthermore, it allowed players, coaches, and spectators to simultaneously visually perceive the spin rate, facilitating immediate and intuitive feedback during training.

1. [1] A. Ikeda and K. Mori, “Basic analysis for evaluation of tennis volley skill using body propagated vibration sensing,” J. Robot. Mechatron., Vol.36, No.5, pp. 1235-1242, 2024. https://doi.org/10.20965/jrm.2024.p1235
2. [2] K. Kurita, “New detection technique for timing of contact and noncontact of athlete’s foot with the ground in sports,” Int. J. Automation Technol., Vol.5, No.2, pp. 233-235, 2011. https://doi.org/10.20965/ijat.2011.p0232
3. [3] K. Fujii, “Data-driven analysis for understanding team sports behaviors,” J. Robot. Mechatron., Vol.33, No.3, pp. 505-514, 2021. https://doi.org/10.20965/jrm.2021.p0505
4. [4] C. Yeung, R. Bunker, and K. Fujii, “Unveiling multi-agent strategies: A data-driven approach for extracting and evaluating team tactics from football event and freeze-frame data,” J. Robot. Mechatron., Vol.36, No.3, pp. 603-617, 2024. https://doi.org/10.20965/jrm.2024.p0603
5. [5] J. Furusho, M. Sakaguchi, N. Takesue, F. Sato, T. Naruo, and H. Nagao, “Development of a robot for evaluating tennis rackets,” J. Robot. Mechatron., Vol.13, No.1, pp. 74-79, 2001. https://doi.org/10.20965/jrm.2001.p0074
6. [6] A. Ming and M. Kajitani, “Development of a golf swing robot to simulate human skill,” J. Robot. Mechatron., Vol.12, No.3, pp. 325-332, 2000. https://doi.org/10.20965/jrm.2000.p0325
7. [7] A. Ming and M. Kajitani, “Human dynamic skill in high speed actions and its realization by robot,” J. Robot. Mechatron., Vol.12, No.3, pp. 318-324, 2000. https://doi.org/10.20965/jrm.2000.p0318
8. [8] T. Maruyama, C. Xu, A. Ming, and M. Shimojo, “Motion control of ultra-high-speed manipulator with a flexible link based on dynamically coupled driving,” J. Robot. Mechatron., Vol.18, No.5, pp. 598-607, 2006. https://doi.org/10.20965/jrm.2006.p0598
9. [9] S. Suzuki, “Torque planning of a new golf-swing robot to emulate skillful,” J. Robot. Mechatron., Vol.16, No.4, pp. 355-361, 2004. https://doi.org/10.20965/jrm.2004.p0355
10. [10] S. Pu, “Development and application of sports video analysis platform in sports training,” J. Adv. Comput. Intell. Intell. Inform., Vol.23, No.1, pp. 139-145, 2019. https://doi.org/10.20965/jaciii.2019.p0139
11. [11] M. Takeuchi, J. Shimodaira, Y. Amaoka, S. Hamatani, H. Hirai, and F. Miyazaki, “Reconstruction of human skills by using PCA and transferring them to a robot,” J. Robot. Mechatron., Vol.26, No.1, pp. 51-58, 2014. https://doi.org/10.20965/jrm.2014.p0051
12. [12] K. Kamijo, S. Fukuzumi, and T. Yamazaki, “Virtual reality system using psychological and physiological data, – An application to sports image training system –,” J. Robot. Mechatron., Vol.4, No.1, pp. 25-30, 1992. https://doi.org/10.20965/jrm.1992.p0025
13. [13] K. Arasawa and S. Hattori, “Automatic baseball video tagging based on voice pattern prioritization and recursive model localization,” J. Adv. Comput. Intell. Intell. Inform., Vol.21, No.7, pp. 1262-1279, 2017. https://doi.org/10.20965/jaciii.2017.p1262
14. [14] T. Hayashi, “Spin-rate Kakumei,” BASEBALL MAGAZINE SHA Co., Ltd., 2019 (in Japanese).
15. [15] H. Ryutaro, “Aerodynamics in baseball game,” The Japan Society of Fluid Mechanism Nagare, Vol.39, pp. 163-166, 2020.
16. [16] H. Kazama, M. Hariyama, and M. Kameyama, “Design of a VLSI processor based on an immediate output generation scheduling for ball-trajectory prediction,” J. Robot. Mechatron., Vol.12, No.5, pp. 534-540, 2000. https://doi.org/10.20965/jrm.2000.p0534
17. [17] M. Hirano, K. Iwakuma, and Y. Yamakawa, “Multiple high-speed vision for identical objects tracking,” J. Robot. Mechatron., Vol.34, No.5, pp. 1073-1084, 2022. https://doi.org/10.20965/jrm.2022.p1073
18. [18] T. Watanabe and T. Matsuno, “Development of a pitching practice ball with rotational speed measurement and visual feedback,” Proc. of the Robotics and Mechatronics Conf. 2024, 2P1-I10, 2024. https://doi.org/10.1299/jsmermd.2024.2P1-I10
19. [19] T. Watanabe and T. Matsuno, “Proposal of pitching practice ball that visualize rotation rate and measurement method for improving pitching skills,” Proc. of SHD 2024, B-3-1, 2024. https://doi.org/10.1299/jsmermd.2024.2P1-I10
20. [20] Rapsodo. https://rapsodo.com/ [Accessed April 27, 2026]
21. [21] TrackMan. https://www.trackman.com/baseball [Accessed April 27, 2026]
22. [22] Hawk-Eye Innovations Ltd. https://www.Hawkeyeinnovations.com/ [Accessed April 27, 2026]
23. [23] Mizuno Corporation (in Japanese). https://jpn.mizuNo.com/baseball/products/MAQ [Accessed April 27, 2026]
24. [24] SSK CORPORATION (in Japanese). https://www.sskbaseball.com/item/detail/2084 [Accessed April 27, 2026]
25. [25] STRIKE Smart Baseball. https://en.shop.jingletek.com/ [Accessed April 27, 2026]