A demand of search and rescue operations using robotic technology increases to mitigate a natural disaster. In searching tasks with mobile robots, particularly in debris-covered environment, there is a trade-off between high-traversability on bumpy surfaces (likely to large robots) and exploration in limited areas (likely to small robots). With this in mind, we developed a small transformable mobile robot that uses a variable wheel diameter and stabilizer length. In its most compact form, the robot is deployable in limited areas and, in its fully expanded form, it traverses relatively large obstacles by expanding its wheel diameter. In this paper, development is detailed in the former sections, and geometric analysis and experiment of its step-climbing capabilities is introduced in the latter sections.

1. [1] Special issue: Special project for earthquake disaster mitigation in urban areas development of advanced robots and information systems for disaster response, Journal of Robotics Society of Japan, Vol.22, No.5, pp. 1-44, 2004 (in Japanese).
2. [2] Special issue of advanced robotics: Advanced research and development of robotics for search and rescue, Journal of Advanced Robotics, Vol.19, No.3, pp. 219-347, 2005.
3. [3] B. Kratochvil, B. J. Nelson, N. Papanikolopoulos, A. Drenner, I. Burt, and K. B. Yesin, “Communication and mobility enhancements to the scout robot,” In Proceedings of the 2002 IEEE/RSJ International Conference on Intelligent Robots and Systems, pp. 865-870, Lausanne, Switzerland, 2002.
4. [4] M. Sasaki, T. Tanaka, A. Kitagawa, H. Tsukagoshi, and Y. Mori, “Development of jumping & rolling inspector to improve the debris traverse ability,” Journal of Robotics and Mechatronics, Vol.15, No.5, pp. 482-490, 2003.