The WiFly: Flapping-Wing Small Unmanned Aerial Vehicle with Center-of-Gravity Shift Mechanism. - Taichi Nozawa; Keita Nakamura; Ryosuke Katsuyama; Shunki Kuwajima; Ziyan Li; Akira Nomizu; Riku Okamoto; Toshitatsu Munakata; Takanobu Watanabe (J. Robotics Mechatronics, 2021)