Feedback methods for collision avoidance using virtual fixtures for robotic neurosurgery in deep and narrow spaces. - Nakazawa, Atsushi; Nanri, Kodai; Harada, Kanako; Tanaka, Shinichi; Nukariya, Hiroshi; Kurose, Yusuke; Shono, Naoyuki; Nakatomi, Hirohumi; Morita, Akio; Watanabe, Eiju; Sugita, Naohiko; Mitsuishi, Mamoru (2016)