Masahiro Sekimoto Suguru Arimoto Sadao Kawamura Ji-Hun Bae Skilled-motion plannings of multi-body systems based upon Riemannian distance. 1233-1238 2008 ICRA http://dx.doi.org/10.1109/ROBOT.2008.4543372 conf/icra/2008 db/conf/icra/icra2008.html#SekimotoAKB08