Shuuji Kajita Kenji Kaneko Mitsuharu Morisawa Shinichiro Nakaoka Hirohisa Hirukawa ZMP-based Biped Running Enhanced by Toe Springs. 3963-3969 2007 conf/icra/2007 ICRA http://dx.doi.org/10.1109/ROBOT.2007.364087 db/conf/icra/icra2007.html#KajitaKMNH07