Yanmei Li Imin Kao Stiffness Control on Redundant Manipulators: a Unique and Kinematically Consistent Solution. 3956-3961 2004 conf/icra/2004 ICRA http://dx.doi.org/10.1109/ROBOT.2004.1308887 db/conf/icra/icra2004-4.html#LiK04