A. Ailon R. Lozano Controller-observers for set-point tracking of flexible-joint robots including Coriolis and centripetal effects in motor dynamics. 1329-1331 1996 32 Automatica 9 http://dx.doi.org/10.1016/0005-1098(96)00075-1 db/journals/automatica/automatica32.html#AilonL96