A high-precision positioning servo controller based on phase/frequency detecting technique of two-phase-type PLL. - Takashi Emura; Lei Wang; Masashi Yamanaka; Hisashi Nakamura (IEEE Trans. Ind. Electron., 2000)

Circular/Spherical Robots for Crawling and Jumping. - Yuuta Sugiyama; Ayumi Shiotsu; Masashi Yamanaka; Shinichi Hirai (ICRA, 2005)