Michele Aicardi Giorgio Cannata Giuseppe Casalino Giovanni Indiveri Cusp-Free, Time-Invariant, 3D Feedback Control Law for a Nonholonomic Floating Robot. 300-311 2001 20 I. J. Robotic Res. 4 http://ijr.sagepub.com/cgi/content/abstract/20/4/300 db/journals/ijrr/ijrr20.html#AicardiCCI01