Research of 3-DOF active rotational ball joint. - Yong Yu 003; Yoshitaka Narita; Yoshinori Harada; Toshimi Nakao (IROS, 2009)

Development of Active 3-DOF Rotational Ball Joint with Hollow Shaft Motors. - Yong Yu 003; Yoshitaka Narita; Yoshinori Harada; Toshimi Nakao (J. Robotics Mechatronics, 2013)