“…Quadrupedal locomotion presents good intrinsic stability features, but the coordination of the motion of four legs is non-trivial to control. Different trajectory generation techniques have been adopted (Kimura et al, 1989;Raibert, 1990;Sakakibara et al, 1990;Kramy and Orin, 2003;Golubovic and Hu, 2003a,b;Tsujita et al, 2005;Hu and Gu, 2005;Iida et al, 2005;Kim et al, 2006;Rebula et al, 2007;Pongas et al, 2007;Hebbel et al, 2007;Chae and Park, 2008;Kim et al, 2008), and the efforts in this field of research led to proficient results in the development of different gaits, from the slow walk to gallop. Raibert (1986) provides a good overview of legged locomotion, with particular attention given to quadrupeds.…”