Volcanic ash observation in active volcano areas using teleoperated mobile robots - Introduction to our robotic-volcano-observation project and field experiments. - Keiji Nagatani; Ken Akiyama; Genki Yamauchi; Hikaru Otsuka; Takuma Nakamura; Seiga Kiribayashi; Kazuya Yoshida; Yasushi Hada; Shin'ichi Yuta; Kenichi Fujino; Tomoyuki Izu; Randy Mackay (SSRR, 2013)

Thrust loss saving design of overlapping rotor arrangement on small multirotor unmanned aerial vehicles. - Hikaru Otsuka; Keiji Nagatani (ICRA, 2016)

Single-Use Aircraft Launch System with Small Helium Balloon for 1 kPa Flight Testing. - Hikaru Otsuka; Hiromi Ueno; Renta Oishi; Naoki Hayashi; Ryoma Nakayama; Hiroshi Tokutake (J. Robotics Mechatronics, 2024)