Cyrille Collette Alain Micaelli Claude Andriot Pierre Lemerle Robust balance optimization control of humanoid robots with multiple non coplanar grasps and frictional contacts. 3187-3193 2008 ICRA http://dx.doi.org/10.1109/ROBOT.2008.4543696 conf/icra/2008 db/conf/icra/icra2008.html#ColletteMAL08